Product Information - Automotive Spark plugs

Diagnostics and replacement parts all from one supplier

Only Bosch, the leading original equipment supplier, can provide fully comprehensive system expertise for workshops and the aftermarket.

Motor vehicle components Supply, sales and logistics fWorldwide logistics network fMore than 130 000 different replacement parts f

Diagnostics Testing systems fESI[tronic] software fWorkshop equipment fTechnical hotline and information database fService training fActive assistance for all makes f

For further information click onto: www.bosch.com

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Contents

At a glance: PIA Spark plugs

A long history of progress More than 100 years ago Bosch presented the first spark plug in combination with a high-voltage magneto. This reliable product for high-speed engines solved the ignition problem once and for all. In conjunction with industrial manufacturing processes, the Bosch spark plug paved the way for the immense growth of motor vehicle production in the following decades.

Today‘s modern vehicles have to satisfy ever increasing demands. They are judged by their fuel economy, low emission levels and the greatest possible driving pleasure. Efforts to reconcile all these aims can no longer just be concentrated on improvements to par-ticular components. Progress can only be achieved with an all-round approach – system expertise and an understanding of the complex relationships between the sub-systems enable Bosch to create new, pioneering overall concepts.

In conjunction with leading motor vehicle manufacturers, Bosch develops and produces both separate compon-ents such as spark plugs and complete systems. This same experience and high original equipment quality standard are also invested into the aftermarket sec-tor. The Bosch product range can thus offer outstan-ding quality and reliability while attaining a high level of market coverage. Another excellent feature is the professional assistance offered to the trade and workshops.

Product Information (Automotive) for spark plugs, or PIA for short, is designed to supplement the existing sources of information on the Bosch spark plug range, the individual products and their applications. It is a concise guide to the principal facts, providing an up-to-date, quick reference to each item and thus presenting a consistent approach to sales arguments for all spark plugs. The PIA also describes technical features, customer services and the full range of Bosch expertise in the spark plug sector.

4 - 5 Global presence: Production, service and sales

6 - 9 The history of the spark plug

10 - 11 Quality from the spark plug inventors

12 - 15 First choice for original equipment and motor sports

16 - 17 The spark plug – the nerve center of the engine

18 - 19 Design features

20 - 21 Spark plug faces – and what they reveal

22 - 23 The complete Bosch spark plug range: A summary

24 - 25 Bosch Super

26 - 27 Bosch Super plus and Double platinum

28 - 29 Bosch Super 4

30 - 31 Bosch Super special and special applications

32 - 33 Spark plug type designation

34 - 35 Spark plugs for gas engines

36 - 37 Bosch Diagnostics and practical spark plug advice from Bosch

38 - 39 Advanced training

40 - 41 Sales promotion

42 - 43 Glossary

44 - 47 Frequently asked questions

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Global presence

Exciting ideas, close customer contact: Production, development and sales

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Bosch – all-round expertise: Close contact with vehicle manufacturers fFull range of original equipment from compo- fnents right through to coordinated systems Innovations for advanced automobile tech- fnology International development and manufacturing fnetwork in 5 countries

Spark plug expertise Leading automobile manufacturers rely on Bosch spark plugs for surfisticated technology and high quality standards. As pioneers in the area of ignition systems, Bosch can offer an extensive product range:

Super fSuper Plus fSuper 4 fPlatinum fSpecials fGas applications fOther applications fKomplettes Programm f

Comprehensive range In addition to a full range of more than 10 000 spark plugs for all types of engine, Bosch can also supply the appropriate replacement and wear parts for the aftermarket and workshops as well as the correspon-ding testing and diagnostic systems.

Worldwide development and production An international manufacturing network develops and produces the entire spark plug product range in 5 countries. This means that components and products can be created close to the market while maintaining consistent manufacturing and quality standards. In this way, the constant high quality of Bosch products is always guaranteed.

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Worldwide presence

BambergGermany

SaratowRussia

NanjingChina

AratuBrazil

NaganathapuraIndia

The history of the spark plug

Bosch present the very first spark plug: A real boost to mobility

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More than a century of experience Bosch invented the spark plug fBosch manufacture more than 350 million fspark plugs every year Worldwide production to the same constant fhigh quality standard

Bosch spark plugs. A history of success. More than 100 years ago Bosch presented their spark plug with high-voltage magneto to the world and thus solved the problem of ignition in the early days of automotive engineering. Thanks to industrial pro-duction processes, cars became affordable for the general public. On 7th January 1902 Bosch was awarded a patent on their spark plug and this marked the start of the success story. Since then Bosch has developed more than 20 000 types of spark plug.

Nothing but the best. Bosch products undergo continues development process to maintain quality standards. In this way, it has been possible to continuously enhance perfor-mance since the invention of the Bosch spark plug. The outcome: Spark plugs have become more durable and last for up to 30 000 km, with some special models even managing 100 000 km.

Bosch spark plugs. Still the number 1 Bosch produces a million spark plugs at the Bamberg works alone. Every day. There are now also Bosch manufacturing plants in other countries and on other continents, for example in India, Brazil, Russia and China. Altogether that adds up to a world-wide pro-duction total of more than 350 million spark plugs a year. If all the spark plugs manufactured to date were to be placed end to end, they would form a chain 350 000 kilometers long reaching to the moon.

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1902 – The first spark plug with high-voltage magneto is developed by Bosch and revolutionizes motoring

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More than 100 years old. But just as innovative as ever

The history of the spark plug

Copper core in ground electrode: To improve heat dissipation, the center and ground electrodes are provided with a copper core. This also reduces the amount of wear.

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Platinum range: The special platinum spark plugs from Bosch have sintered-in center electrodes made of pure platinum. They are thus extremely resistant to wear and have a far longer service life.

Surface gap design: The layout of the ground electrodes is such that only surface air gap sparks are formed. This produces a larger arc and results in greatly enhanced ignition pro-perties.

Laser double platinum: Laser-welded platinum tips (center electrode) and platinum-tipped ground electrodes ensure a high power yield and an above average service life.

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100 years of spark plugs – 1902 to 2002

Years of experience and intensive spark plug develop-ment efforts in close association with virtually all vehicle manufacturers have made Bosch one of the world‘s leading suppliers for original equipment and the after- market and also the market leader in Europe.

Research, development, inspection: Quality is not a matter of chance

Quality from the spark plug inventors

Warranty: Bosch spark plugs can be used in all engines in accordance with the applicable recommendations issued by Bosch. Bosch provides warranty coverage for assured properties and perfect working order in line with the current state of the art. The warranty period for material and manufacturing defects is 24 months. Normal wear and tear is not covered by the warranty.

Research and development: At Bosch, spark plugs are constantly adapted to the latest developments in engine technology. Whether an engine is of the four valve, lean mix or low-consump-tion gasoline direct injection type – the wide range of applications of Bosch spark plugs is the result of design modifications and the use of particularly hard-wearing metals such as platinum, iridium or yttrium. And Bosch will continue to promote the development of new spark plugs in the future as well.

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Cheap copy (two aspects): Outwardly hardly distinguishable from the genuine article but a world of difference in quality.

Deliberate deception. Manufacturers of imitation products copy the design of Bosch spark plugs to wrongly create the impression that they are offering the same high quality as Bosch. The use of this „stolen“ appearance is a deliberate attempt to deceive the aftermarket and consumers.

Cheap production, inferior raw materials. Bosch spark plugs are the product of extensive re-search, careful production and more than a century of experience. None of which can be offered by imi-tation spark plugs, usually from countries with low labor costs such as China.

Almost identical – but not when it comes to per-formance. Even experts often find it difficult to distinguish bet-ween genuine and imitation products on the basis of their outward appearance or packaging. The lower price can sometimes be the sign of a cheap copy.

The quality inside is what counts. The true worth of a spark plug only comes to the fore when it is put to the test. A closer look at the inner workings is needed to reveal the poor manu-facturing quality and inferior materials resulting in unsatisfactory performance.

Imitations – no match for the genuine item. The inferior quality of imitation products can have disastrous consequences for the engine: Misfiring, starting problems and even costly engine damage. A Bosch study of the design, materials and workman-ship of various imitation products revealed serious deficiencies in almost every case.

So don‘t take any risks: Only buy top quality Bosch spark plugs from authorized dealers.

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It is an offence to knowingly buy or sell imitations of Bosch spark plugs.

Bosch spark plugs in comparison with competitors

Competitors

Unrivalled: Bosch is the motorists‘ number 1

A matter of trust: Vehicle manufacturers count on Bosch

First choice for original equipment

Motorists have no doubts. For the third time in suc-cession, Bosch was voted the most popular make in the spark plug sector by more than 100 000 readers of the magazines „auto motor und sport“ and „msa“.

This high level of quality and reliability is the product of a close, successful working relationship between Bosch and leading international vehicle manufacturers and their joint development projects.

Numerous certificates furnish proof of compliance with the high quality demanded at international levels. It‘s reassuring to know that the same high Bosch quality standards apply in all factories.

Certification for all Bosch factories guarantees – Quality right from the start

Spark plugs from Bosch – Europe‘s no. 1 original equipment and the aftermarket supplier

Way out in front for the third time running: German motorists vote for Bosch spark plugs as „Best Brand“

In Europe nearly every second vehicle is fitted with Bosch spark plugs when it leaves the factory

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Bosch original equipment spark plugs for motor vehicles:

Alfa RomeoAudiBMWCadillac CitroënDeawooFiatFordLancia

Mercedes-BenzMitsubishiOpelPeugeotPorscheRenaultSaabSeatSkoda

SmartSsangyongToyotaVauxhallVolvoVolkswagen

Many leading vehicle manufacturers decided in favor of Bosch spark plugs right from the start. And there are good reasons for doing so – after all, Bosch is synonymous with outstanding quality, innovation, in-depth expertise and an unrivalled range in the fields of gasoline injection and ignition. By constantly developing new spark plug concepts, Bosch can provide a guarantee of high-grade, state-of-the-art products.

A close working relationship for perfect results All Bosch original equipment spark plugs are developed in close association with vehicle manufacturers and are thus tailor-made to suit every engine.

Important for workshops and the aftermarket sector: Bosch only supplies original equipment quality to the aftermarket.

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The winners‘ choice: Bosch spark plugs head the field

Top technology for outstanding results

Bosch spark plugs fear no comparison When it comes to satisfying the toughest standards, Bosch spark plugs never let you down. No wonder they are so successful in international motor sports.

Pole position for Bosch What ever the situation - be it the Le Mans 24-hour race, the Indy Racing League, the V8 Supercar Series, the Swedish Touring Car Championship or the DTM in Germany – spark plugs from Bosch have got what it takes to be a winner. One of the guarantees for this is the innovative, extremely durable and wear resistant yttrium alloy.

High-tech developed for motor sports goes into series production Bosch spark plugs are always one step ahead in the motor sports sector – thanks to special technical properties and standards and the use of high-grade materials such as yttrium. Specially designed to cope with the exacting demands of motor sport, these innovations are also incorporated into original equip-ment spark plugs. In fact they are often perfected still further before going into series production for workshops and the aftermarket.

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Bosch spark plugs are always amongst the front runners in the DTM.

Bosch makes it mark in motor sports For the ninth consecutive year Bosch is involved in the DTM. The extremely popular international touring car race series, which is broadcast live not only in Europe and Africa but also in China and North America, attracts more spectators than most other motor sports events. And Bosch‘s support is clear for all to see: On the rear windows of vehicles, in the in-board cameras, in the pits and - most recently - on the windshield as well.

Spark plugs are not the only driving force behind victories As well as acting as sponsor for the DTM, Bosch provide the absolute top quality technology on which racing teams depend. That is why all DTM vehicles are equipped with Bosch spark plugs. What‘s more, the entire engine management system, the cockpit displays, the sensors, injectors, starters and alternators all come from Bosch.

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Deutsche Tourenwagen Masters Deutsche Tourenwagen Masters Swedish Touring Car Championship Indy Racing League Indy Racing League

The spark plug – the nerve center of the engine

The latest expertise: What spark plugs have to offer

Bosch spark plugs provide workshops and the after-market with the latest original equipment trends. Two examples: The profiled ground electrode and the interference suppression resistor.

New technology for reliable ignition: The profiled ground electrode The profiling of the ground electrode ensures greater ignition reliability thanks to more rapid sparkover and mixture ignition. Added advantages:

Increased cold starting reliability fEnhanced combustion protects engine and fcatalytic converter Reduced fuel consumption by avoidance of fmisfiring

Simply the best:Spark plugs with interference suppression resistorIn the original equipment sector, increasing use is being made of spark plugs with interference suppression resistor, as a way of protecting electronic systems in the vehicle against electromagnetic interference. For this reason, Bosch also offers suppressed spark plugs for the replacement parts market:

Maximum interference suppression rate fReliable operation of all electronic systems such fas ABS, TCS and ESP® No radio reception interference f

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Always up-to-date Workshops and the aftermarket benefit fdirectly from the latest original equipment technology Maximum reliability and a long service life fGuaranteed protection for engine and fcatalytic converter

The function of the spark plug It‘s really quite simple: The spark plug has to ignite the air-fuel mixture in the combustion chamber of a gasoline engine by means of an electric spark. Whenever needed, always at the right time, over and over again. It

must guarantee reliable cold starting fmust operate without fail over its entire service life fmust not overheat even if operated for long periods fat maximum load

Applications Vehicles and machinery are driven by gasoline engines wherever mobility and power are essential:

Cars fCommercial vehicles fMotorcycles fBoats/ships fAgricultural and construction machinery fPower saws fGardening implements f

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The key to mobility: Spark plugs govern the „heart beat“ of gasoline engines

Spark plugs have a lot to contend with: Top performance even in the toughest conditions

Quality at every step: The Bosch spark plug production process

Design features

Requirements: Electrical properties Voltages of more than 30 000 V must not cause finsulator breakdown The electric resistance of the insulator must be fguaranteed even at temperatures of 1 000 °C

Requirements: Chemical properties Resistant to all chemical processes in the com- fbustion chamber Stable at combustion temperatures up to 3 000 °C fResistant to corrosive deposits contained in the fuel f

Requirements: Thermal properties Resistance to rapid, extreme changes in temperature f(hot combustion gases and cold air-fuel mixture) Good heat dissipation to the cylinder head fMinimal heat generation at the connection end of fthe spark plug

Requirements: Mechanical properties Reliable gas-tightness at pressures up to 100 bar fResistance to tightening forces on assembly f

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All from one supplier Spark plugs must offer the greatest possible reliability despite being subject to extreme wear and tear. Even the most minute fault can result in costly engine damage. That‘s why Bosch – the only manufacturer in Germany to do so – produce all their own spark plug components.

Nickel-plated spark plug shell and threaded section: To prevent corrosion and seizure of the thread in the aluminum cylinder head.

Effective leakage current barriers: Prevent flashover and thus misfiring.

Welding copper and nickel-yttrium tablets to circular blank

Impact extrusion in 4 steps – step 1

Impact extrusion in 4 steps – step 4

Contact glass seal (powder)

Resistor glass seal (powder)

Imprinting, glazing insulator, mounting center electrode,filling in contact and resistorglass seal powder, mountingconnection rod, annealing

Internal sealing washer

External sealing washer

SAE terminal nut

Mounting internal sealingwasher and insulator into shell, cold crimping, hot crimping, screwing on SAE terminal nut, cutting and bending center electrode, adjusting electrode gap, mounting external sealing washer

Cutting from wire

Impact extrusionin 5 steps – step

Impact extrusionin 5 steps – step

Latheing andwashing shell

Weldingground electrode

Rolling thread andembossing shell

Nickel plating

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Impact extrusion in 3 steps – step 3

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Interference suppression resistor: Reliable operation of all electronic systems and no radio reception interference.

Ground electrode: Positioning, number and geometry have an influence on the sparking process and service life.

Heat-shrink fitting: Guarantees absolute gas-tightness and a precise heat range.

Compound center electrode: Copper core with high thermal conductivity in wear-resistant chromium-nickel sheath for rapid attainment of operating temperature. Provides protection against thermal overload, corrosion and spark erosion.

Design and operation: Center electrode Pre-assembly Final assemblySuper plus

Spark plug shell

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Further developments and trends

Continuous development of a great idea – The spark plugs of tomorrow

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Minimal installation dimensionsPowerful, efficient engines require a lot of air to provide optimum combustion of the fuel.However, more air also means larger ducts in the inlet and outlet valve. This leaves less space for installation of the spark plug. In other words, the smaller the diameter of the spark plug, the more options are available to engine designers.

Perfect spark plugs are the result of computer simulationThanks to a new development method, Bosch is hot on the heels of the perfect spark plug for direct injection gasoline engines. The only simulation of its kind in the world

Creates virtual spark plug designs fVisualizes processes in the engine fOpens up new options for perfect derivation of fmeasuring results and optimization of spark plugs

At critical operating points in the partial load and idling speed range, optimized spark plugs result in:

Increased ignition reliability fReduced fuel consumption and pollutant emissions fOptimum catalytic converter protection f

Fighting nano-flashes - Less platinum in spark plugsIn conjunction with respected materials scientists and supported by the German Ministry of Research, Bosch is conducting research into extremely reliable and durable electrode and contact materials for electrical components. The focus is on electrical ero-sion due to so-called nano-flashes.With each ignition process, these tear nanometer-sized craters from the electrodes, causing permanent damage to them.

Based on maximum precisionModern internal combustion engines are highly com-plex systems, in which every detail needs to be pre-cisely designed to work with the others. Spark plugs are an important component, and are faced with totally new requirements, due to the latest generation of direct injection systems.The basis for meeting all of these requirements is almost tolerance-free production and new develop-ments in materials, geometry and manufacturing methods.

New materialsModern engines operate with extremely high combu-stion chamber temperatures. This impacts the spark plugs. It increases the wear on the electrodes, which needs to be offset by the use of appropriate materi-als that are more resistant to arc erosion. Bosch uses high quality alloys, for example platinum, iridium and rhodium.

Long ignition spark positionThe layer charging method used in modern direct fuel injection, demands exact placement of the ignition spark in the area of the combustion chamber in which the ignitable mixture is located. A long spark position provides the necessary reliability.

Aligned ground electrodePrecisely produced spark plugs with ground electrodes already aligned during production guarantee reliable ignition in engines with fuel spray direct injection. The installation angle and installation position relative to the injector are defined according to the specific engine type. Narrow production tolerances, modern measuring systems and, of course, close cooperation with engine manufacturers, ensures optimum align-ment of the ground electrodes. An incorrect installation angle can result in malfunctions.

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Expensive platinum ensures that the electrodes retain their resistance in the long term, but optimized materials could replace platinum in the future. This would make spark plugs cheaper and, at the same time, more durable.

Smaller, more efficient, longer lastingThanks to major expenditure on research and development, Bosch has worked closely with international car manufacturers to bring new spark plug designes to production, which are optimized to meet the needs of modern gasoline engines. Above all, this means – less fuel consumption, lower emissions and reduced dimensions.

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At a Glance:Spark Plug Faces

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Insulator nose with color between whitish or yellowish-grey and russet. Engine OK. Correct heat range. A/F mixture adjustment and timing OK, no ignition miss, cold-start enrichment functioning correctly. No residues from lead fuel additives or engine-oil additives. No overheating.

Thick ash coating from oil and fuel additives on insulator nose, in scavenging area (an-nular orifice) and on ground electrode. Loose to cinder-like structure. Cause: Alloying constituents, particularly from oil, may deposit such ash in the combustion chamber and on the spark plug face.

Insulator nose, electrodes, and sparkplug shell covered with a felt-textured, matt-black coating of soot.Cause: Incorrect A/F mixture adjust-ment (carburetor, fuel injection): A/F mixture too rich, extremely dirtly air filter, automatic choke or choke cable defective, vehicle only used for extremely

Center electrode partially melted, blistered, spongy insulator nose tip. Cause: Thermal overload due to auto- ignition, e.g. on account of excessively advanced ignition timing. Heat range possibly too low. Effect: Misfiring, loss of power (engine damage). Remedy: Check engine, ignition and mixture formation. New spark plugs with correct heat range.

Insulator nose, electrodes, and spark plug shell covered with shiny oil layer of soot or carbon.Cause: Excessive oil in combustion chamber. Oil level too high, severe wear of piston rings, cylinder walls, or valve seals/guides. Two-stroke engines: Too much oil in fuel mixture.

Cauliflower-like appearance of electrodes. Possibly deposition of foreign matter. Cause: Thermal overload, e.g. on account of excessively advanced ignition timing, combustion residue, defective valves or defective ignition distributors. Effect: Loss of power prior to total failure (engine damage). Remedy: Check engine, ignition and mixture formation. New spark plugs.

Cause: Failure to observe spark plug replacement intervals.Effects: Ignition miss, especially during acceleration (ignition voltage not adequate for bridging wider electrode gap). Starting difficulties.Remedy: New spark plugs.

Cause: Corrosive fuel and oil additives. Unfavourable flow conditions in com-bustion chamber, possibly on account of deposits, engine knocking. No thermal overload. Effect: Misfiring, particularly on accelera-tion (ignition voltage no longer sufficient for large electrode gap). Poor starting performance. Remedy: New spark plugs.

Thick, brownish-yellow glaze, thick in some places, possibly with greenish tint, has formed on the insulator nose.Cause: Fuel additives containing lead: The glaze forms when the engine is operated at high loads after extended part-throttle operation.

Effect: Can lead to auto-ignition with loss of power and engine damage. Remedy: Repair engine. Use new spark plugs and possibly different oil.

short distances, spark plug too cold, heat range too low.Effects: Ignition miss, poor cold starts.Remedy: Adjust A/F mixture and cold-start system, check air filter.

Center electrode melted away and ground electrode severely corroded. Cause: Thermal overload due to auto- ignition, e.g. on account of excessively advanced ignition timing. Effect: Misfiring, loss of power, possibly engine damage. Overheated center electrode may cause insulator nose to crack. Remedy: Check engine, ignition and mixture formation. New spark plugs.

Effects: Ignition loss. Starting difficulties.Remedy: Overheaul engine, use correct A/F mixture, replace spark plugs.

Firmly adhering reddish orange deposits coat the insulator nose, electrodes and to some extent the spark plug shell. Cause: Fuel additives containing iron. Deposits occur in normal operation after a few thousand kilometers. Effect: The iron in the coating is electri-cally conductive and causes misfiring. Remedy: New spark plugs, cleaning has no effect.

A brownish-yellow glaze, with a greenish tint, has formed on the insulator nose.Cause: Fuel additives containing lead. The glaze forms when the engine is operated at high loads after extended part-throttle operation.Effects: At high loads the glaze becomes electr. conductive, leading to ignition miss.Remedy: New spark plugs, cleaning them is pointless.

Cause: Mechanical damage due to inexpert handling. In borderline cases - particularly following excessive operating time - cracking of insulator nose may be caused by deposits between center elect-rode and insulator nose and by corrosion of center electrode. Effect: Misfiring, sparkover at points not reliably supplied with fresh mixture. Remedy: New spark plugs.

Effects: At high loads the glaze becomes electrically conductive, leading to ignition miss.Remedy: New spark plugs, cleaning themis pointless.

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Partially melted electrodes Ferrocen

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Bosch Super 4

Bosch Super special

Bosch Super / Super plus

The complete Bosch spark plug range

The right product for every application: All the Bosch spark plugs at a glance

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Bosch Super/Super plus For consistently high performance whatever the foperating conditions Factory-set electrode gap fSatisfies manufacturers‘ service life requirements fBosch Super plus – the 55 top products for virtually fall vehicles

Bosch Super 4 Up to 60 % greater efficiency for higher engine foutput Greatly enhanced acceleration characteristics fGreater ride comfort thanks to smoother operation fand superior engine performance Surface air gap principle – always chooses the fbest spark gap

Bosch Super special Special spark plugs for motorcycles, snowmobiles, fgardening implements, motor boats ... For a wide range of equipment fOutstanding starting performance over the entire fservice life Effective protection against corrosion and thread fseizure

All leading automobile manufacturers install Bosch spark plugs as standard equipment. At present the Bosch range contains more than 1 250 versions with 31 different electrode designs to guarantee the right spark plug for every engine – and for around 98 % of all vehicles.

Tailor-made range for workshops and the aftermarket sector The Bosch Super range offers just the right spark plug for every vehicle. Technically, the spark plugs are perfectly designed to satisfy the requirements of each engine. The top range of spark plugs for the most common vehicles – Bosch Super plus – provides market coverage for more than 97 % of vehicles with just 55 types.

Clear-cut spark plug assignment to the engine The clearly marked assignment of spark plugs to engines, in the catalog for example, makes the ordering procedure more straight forward. Each engine is assigned exactly the right spark plug. The simple ID number system permits rapid, reliable identification of the appropriate spark plug. All the details of the Bosch spark plug type designa-tions can be found on Pages 34 and 35.

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The full range A total of 1 250 spark plug versions f31 different electrode designs fFor 98 % of all vehicles fClear-cut assignment for rapid identification fof the right spark plug

Bosch Super

Thousands of millions of spark plugs provide ample proof: The Bosch Super is a real winner

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Air gap design: The ignition spark travels along a direct path to the ground electrode and thus ignites the air-fuel mixture.

Arguments guaranteed to convince all motorists Exactly the right spark plug for every fpassenger car gasoline engine Cuts fuel consumption and reduces harmful femissions Protects engine and catalytic converter f

Arguments guaranteed to convince workshops and the aftermarket

A long service life and reliability keep fcustomers satisfied Clear-cut identification, ease of replacement fCombination of several spark plug types – fless storage space required

Surface gap design: The layout of the ground electrodes is such that only surface air gap sparks, which are particularly long and powerful, can be formed.

Surface air gap design: This design combines both spark paths. Both air gap sparks and surface air gap sparks ignite the air-fuel mixture.

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Millions of applications all round the world The right spark plug for every engine fFor around 98 % of all vehicles fConvincing arguments for all motorists fAvailable individually or in packs of 10 f

Original equipment technology Your customers can rest assured knowing that. The Bosch Super range offers genuine original equipment technology. In other words Bosch quality designed to suit the exact requirements of the engine.

For virtually all gasoline engines The Bosch Super range contains a total of 350 types. The top most frequently used spark plugs have a „plus“ identifiing them is the fastest movers.

The Bosch Super range also includes Bosch double platinum – with a particularly high level of wear resi-stance thanks to the platinum coating on both elec-trodes.

Endurance hardness testing has shown: Electrodes with yttrium alloy are far less susceptible to wear than electrodes with no yttrium additive.

A brief outline of the technology Bosch employs three different spark plug technologies depending on the engine characteristics.

Packaging unit tailored to workshops: All Bosch Super spark plugs are available individually and in packs of 10. Ideal for one-off orders or for keeping a stock of common types.

With yttrium Without yttrium

Geared to all requirements: The Bosch Super Plus is available individually and in packs of 4 or 10

Just right for the workshop: Packs of 1 and 10 to suit every need

Tested in the world of racing, successful in everyday use. Bosch Super plus

Top performance in every phase: Bosch Double Platinum

Bosch Super plus Double platinum

An unconventional material is the source of the out-standing reliability of Bosch Super Plus spark plugs: nickel-yttrium. This rare earth metal alloy guarantees top performance in motor sports.In everyday use it enhances ignition reliability and reduces wear.

This spark plug deserves a medal. The platinum on both electrodes gives the Bosch Double Platinum its name and helps to ensure out-standing ignition reliability and wear resistance. What‘s more, the center electrode with its thickness of just 0.6 mm permits a lower ignition voltage in combination with higher-energy ignition sparks.

The advantages of Bosch Super plus: Excellent protection against corrosion fOutstanding ignition reliability fCompact range with 54 spark plug models fOptimum warehousing fSimple ID number system f

Bosch Double Platinum: Convincing from start to finish

Extremely smooth operation and superior engine felasticity Engine and catalytic converter protection fMaximum service life and wear resistance fNo misfiring throughout the entire service life fOptimum suppression ensures no interference fwith electronic systems Lower ignition voltage, ideal for turbo engines f

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Bosch Super 4

High capacity: The Bosch Super 4 for demanding applications

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Bosch Super 4: The first spark plug with four thin ground felectrodes Reliable ignition based on the surface air fgap principle Superior engine elasticity and high ignition freliability Factory-set electrode gap f

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Bosch Super 4 – the first spark plug with four ground electrodes This heavy-duty retrofit spark plug is a real „power house“ for every engine. The Bosch Super 4 is the first spark plug to feature four thin ground electrodes with a pointed center electrode made of a chromium-nickel alloy. It has a sheat a sheathed copper core and operates on the surface air gap principle. A unique combination: The ignition spark always selects the optimum path for reliable ignition to suit the engine load.

Surface air gap design The surface air gap design selects the optimum path for ignition between the center electrode and the ground electrode. This occurs by way of either an air gap or a surface air gap. The air gap spark follows a direct path and thus ignites the air-fuel mixture. The surface air gap spark travels over charge carriers on the tip of the insulator nose.

Crucial advantages of the Bosch Super 4 Superior engine elasticity for better response fHigh ignition reliability and thus sound protection ffor engine and catalytic converter High power yield thanks to a 60 % increase in fspark plug efficiency Risk of misfiring reduced to a minimum fEnhanced acceleration performance and optimum fengine efficiency Far smoother operation fAlso ideal for retrofitting on older vehicles f

Always complete: The practical packs of 4 in a box or the blister packs of 4 for large display areas.

Innovative technology for even more efficient engines Surface air gap principle with four ground electro- fdes – the optimum spark gap is always selected. Ground electrode wear is evenly distributed over fall four electrodes. The silver-plated center electrode ensures good fheat dissipation and thus avoids the risk of auto- ignition due to overheating. Spark plug efficiency is enhanced by the up to 40 % fincrease in ignition energy.

Water, snow, garden: The Bosch Super special is always ready for action

Special spark plugs for special requirements: The full range from Bosch

Bosch Super special

For gardening enthusiasts and professional users: Mobile, motorized implements are becoming ever more popular and consequently the demand for spark plugs for low-power engines is also increasing. The compact self-service range for gardening implements and forestry equipment from Bosch: Bosch Super special.

Just a few types for all sorts of equipment: The compact Bosch self-service range.In the Super special self-service range you will always find the right spark plug. The customer only need a small sales area, as the compact assortment covers virtually every application:

Leaf blowers fGarden tractors fHedge trimmers fChain saws fLeaf vacuums fPower scythes f

Power supply units fLawnmowers fLawn trimmers fSnow cutters fSnow throwers fWater pumps f

Bosch Super special – all the advantages at a glance: Outstanding starting performance and reliable ignition over fthe entire service life thanks to a chromium-nickel ground electrode. Nickel-plated shell and threaded section for effective protection fagainst corrosion and thread seizure. Sealed connection of center electrode and terminal stud fensures a permanent, tight connection and good electrical conductivity.

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Not just for cars As the inventor and world‘s largest manufacturers, Bosch have produced more spark plugs than any other company. And not just for cars either. Bosch can supply the appropriate spark plugs for virtually any gasoline engine. They are, after all, an important system component for economical, clean and efficient fuel combustion. Unrestricted mobility Bosch Super, Super plus and platinum spark plugs are also used on

Motorcycles and scooters fJetskis and snow mobiles fBoats f

Spark plugs with special electrodes The comprehensive Bosch range is rounded off by special spark plugs for special applications. These are of differing design to suit the corresponding usage conditions and installation situations on the engine.

Powerful spark plugs for demanding applications Spark plugs for motor sports: Designed for constant ffull load operation and high thermal loads Fully shielded spark plugs: The insulator is fsurrounded by a metal shielding sleeve. Added advantage: Water-tight shielding Spark plugs with resistor: A resistor in the lead stops fdisturbance pulses being relayed to the ignition cables and thus prevents interference radiation Spark plugs for stationary engines and emergency fgenerating sets: For exacting demands associated with sustained loading or large engine size

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13 12 11 10 9 8 7 6 5 4 3 2 09 08 07 06

K4

H7

A 12,7

1

17,5L5

19C1

B3

N4

E1

26,5S5

F3

G4

T7

D3

M3

M 18x1,5

D20,8

F16

M 14x1,25 M 14x1,25

H16

M 14x1,25

K14*

M26

M 18x1,5 M 12x1,25

S14

M 10x1

T16

U16

M 10x1

V14

M 12x1,25

W20,8

M 14x1,25

W S

19

M 14x1,25

X17,5

M 12x1,25

Y16

M 12x1,25

Z14

M 12x1,25

B C E G H L M Q R S

❊ ✳

C E P S I

D T Q

R S0,7

T0,8

U1,0

V1,3

+X1,1

Y1,5

Z2,0

W0,9

*11,2

19 17,5

12,7 *11,2 19 17,5

19 17,5 17,519

19 17,5 9,5 7,8 9,5 7,8 12,7

26,5 25 26,5 26,5

1)

25 25 2526,5

1)1)

Spark plug type designation

How to find the right type: The Bosch spark plug type designation

34 35

Quick and easy identification instead of a tedious search: The key below provides an instant explanation of the spark plug code.

Water-tight, for shielded ignition cable dia. 7 mm

Water-tight, for shielded ignition cable dia. 5 mm

Surface gap spark plug without ground electrode

Surface gap spark plug with ground electrode(s)

Half thread Type

Heat range code number

Thread length Spark position

Electrode material

Type of electrode

Version Burn-off resistor

SUPER plus

technology

*The thread length for spark plugs with seat shape D and spark position A or B is 10.9 mm.

Platinum-iridium

Copper Nickel- yttrium

Platinum Silver

Surface air gap spark plug

For motor sports

Quickheat With interference suppression resistor

For low-power engines

0 Differences from basic design 1 P0 design with Ni ground electrode 2 Binary ground electrode 3 Special length thread 4 Extended insulator nose 9 PSA design

10 ● – ● – – –15 ● – ● – – –22 ● – – – ● –222 ● – – – – ●

23 – ● – – ● –232 – ● – – – ●

30 – ● ● – – –302 – ● – ● – –33 – ● – – ● –332 – ● – – – ●

1) Double hexagon

Seat shape and thread

Center electro

de

with welded-on

platinum wafer

Diameter 0.8 or

1.1 mm possible

Center electro

de

with welded-on

platinum wafer

Diameter 0.6 or

0.8 mm possible

Ground electrode

Mono nickel-

yttrium

Ground electrode

Binary nickel-

yttrium

Ground electrode

Mono nickel-yttr

ium

with laser-a

lloyed

platinum in

lay

Ground electrode

Binary nickel-

yttrium with

laser-allo

yed

platinum in

lay

Spark plugs for gas engines

Reliable gas engine ignition: Bosch can offer the right solution

36

Fully equipped to deal with the special features of gas engines

The right spark plug for every gas fapplication Ideally suited to the particular frequirements of gas engines Platinum spark plugs help to counteract fthe high degree of wear

37

Different fuel, different spark plug Before they decide on a gas engine, motorists weigh all sorts of aspects: Consumption, safety and avai-lability of the fuel etc. In the trade, however, it is essential to be familiar with the particular technical features of gas engines. For instance, that new spark plugs with modified properties are required when converting an engine to gas operation.

Regular replacement maintains performance and protects the engine Spark plugs in gas engines are subject to greater wear than in gasoline engines. They should therefore be replaced at intervals of 15 000 km at the latest. As they have no way of knowing beforehand which engine the kit is going to be fitted in, manufacturers of conversion kits are not generally in a position to provide any definite information about the spark plugs. Your competence and technical expertise are called for to be able to decide on the correct spark plug and the appropriate replacement interval.

Greater competence guarantees more customers It‘s worth investing the effort to find out more about the special requirements for spark plugs for gas-driven vehicles. This is a good way of keeping customers, gaining new ones and earning the loyalty of motorists who switch to gas.

Switching from gasoline to gas means changing the spark plugs

The differences between gasoline and gas engines There are a few points to note when converting an engine from gasoline to gas operation:

Gas requires a higher ignition voltage than gasoline. fWhereas the level required for an engine running on gasoline is 14 kV for example, 16 kV are needed for reliable ignition under the same conditions when using gas. Gas operation results in a higher operating ftemperature in the combustion chamber. Electrode wear is accelerated by the higher ignition fvoltage and the higher operating temperature in the combustion chamber

Adaptation of spark plugs to gas engines Spark plugs from Bosch can be perfectly matched to the requirements of gas engines:

Automatic compensation for the higher ignition fvoltage needed is provided by a gas control unit in combination with an integrated ignition timing advance feature. If this is not available, use a spark plug with a 0.7 mm electrode gap or the gap is to be adjusted accordingly. Spark plugs with a lower heat range should be fselected to offset the higher operating temperatures in the combustion chamber.

Bosch spark plugs: Ideal for gas engines as wellBosch spark plugs excel thanks to their high quality. What‘s more, the right spark plug is available for almost every vehicle. Thanks to the material used, Bosch platinum spark plugs in particular are subject to less wear, have a longer service life and are thus ideally suited to use in gas engines.

Gas engines reduce fuel costs, protect the environment – and they need the right spark plugs to suit their special requirements.

Specially for ignition systems: ESI[tronic]-C for diagnosis including trouble- fshooting ESI[tronic]-M with a wealth of information on fgasoline systems

All the professional needs to know: Bosch ESI software and testing systems

Useful hints: Practical spark plug advice from Bosch

Bosch diagnostics

Everything about ignition systems from a single source Complex interlinked motor vehicle systems demand ever more qualified diagnosis from workshops in addition to in-depth repair expertise. Thanks to Bosch Diagnostics, workshops can acquire detailed system information and the full range of testing systems all from the same supplier. Modern, high-performance diagnostic equipment, technical training courses and a hotline service provide workshops with all the necessary repair assistance.

ESI[tronic] software for diagnosis and service

ESI stands for „Electronic Service Information“ and is the name of the software used in the course of Service work. This includes:

System trouble-shooting fMaintenance fRepair instructions f

Testing systems: Professional diagnosis for all makes

Bosch can offer a wide range of test equipment for trouble-shooting and diagnosis. The modular design of all components makes this a sound investment.

Tailor-made for the workshop The ESI[tronic] software was developed with workshop requirements in mind. Straight forward operation, rapid access and a standard system approach for all types of vehicle help to make ESI[tronic] software a user-friendly information tool. Broad market coverage and constant updating are a matter of course. The software packages are of modular design, so that ignition system specialists are able to subscribe to exactly whichever „Info types“ they choose.

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Note: Insofar as they were not made by the motor vehicle or engine manufacturer, the spark plug recommendations were drawn up by Bosch. They apply to standard operating conditions for series models, however not to racing, special and high-performance versions (unless specifically mentioned). Particular operating conditions may make it necessary to use different heat ranges. If spark plugs with the specified electrode gap are not available, the electrode gap must be adjusted using the Bosch spark plug gauge.

Fitting spark plugs with a torque wrench Tightening torque (N • m): 10N • m ≈ 1 kpm for dry, non-greased/non-oiled threads and new seals. Reduce tightening torques by 1/3 for lubricated threads or on re-installation.

Fitting spark plugs without a torque wrench Screw in the spark plug by hand until it is seated in the cylinder head. Spark plugs with a flat seat and new seal are then to be given a further approx. 90° turn with a spark plug wrench. The further turning angle for spark plugs with a conical seat and spark plugs with a used flat seal is approx. 15°.

Spark plug terminal nuts Engines may be fitted with spark plugs of a different length to Bosch spark plugs. 1. Screw out the old spark plugs. 2. Compare to new Bosch spark plugs. 3. If applicable, replace the screwed-on terminal nut A with the longer terminal nut B provided.

39

Bosch diagnostics Bosch parts

The efficient motor vehicle workshop of the future

•ESI[tronic]software •Aftermarketproducts

•Testingsystems •Replacementparts

•Servicetraining • Newproducts

•Technicalhotline • Exchange

All from one supplier 1 2

M 10 x1 10...15 10...15

M 12 x1,25 15...25 15...20

M 14 x1,25 l <12,7 mm 20...25 15...20

M 14 x1,25 l >12,7 mm 20...40 20...30

M 18 x1,5 30...45 20...35

1 In cast iron 2 In light alloy

Flat seat

1 2

M 14 x1,25 20...40 10...20

M 18 x1,5 30...45 15...23

1 In cast iron 2 In light alloy

Conical seat

Advanced training

Always one step ahead with: Service training, technical hotline and information database

40

Service training: Worldwide – and never far away

The training program includes courses on all ignition systems from Bosch and other manufacturers. Learning by doing means: All the instructors have a wealth of workshop experience and concentrate on practical aspects. The training courses are held on modern workshop premises using the latest vehicle models. Bosch Training Centers can be found all over the world. Courses of instruction, e.g. for wholesalers, can also be held as required at individual locations. Training specifically on gasoline injection is also available in e-learning form.

The home of knowledge: The Plochingen Service Training Center The new Service Training Center in Plochingen was opened in 2005. Around 7 500 employees from official bodies, associations and workshops as well as Bosch instructors from abroad receive training here every year.

Online Help: Problem solutions are just a mouse click away Workshops have round-the-clock access to the extranet-based Bosch Online Help information database. Containing lists of all the problems encountered in recent years, it is a source of efficient self-help for dealing with Service or repair difficulties. Enquiries regarding topics not listed can be submitted by way of a „Trouble Ticket“. Bosch specialists will then tackle the problem and give an immediate response.

Professional knowledge on call

If all else fails, just pick up the telephone: Our technical hotline will be only too pleased to assist workshops and the aftermarket. Whatever the question relating to Service and repair, experienced specialists can provide further assistance for all makes. This not only saves time, it also ensures customers of competent, inexpensive help.

41

Theoretical and practical instruction: Modern Training Centers throughout fthe world Up-to-date, in-depth training courses f24-hour online database fTechnical hotline offering expert assistance fDetailed informative publications f

In the future, workshop activities will concentrate more on the diagnosis of interlinked systems and the specific replacement of high-grade components rather than just the traditional replacement parts business. The professional Service training courses offered by Bosch provide the ideal basis for work- shops to meet this challenge. This theoretical and practical instruction from Bosch imparts detailed information guaranteed to ensure the necessary workshop expertise.

Sales promotion

Advice, information, persuasion: Top class sales promotion

Information for your sales area: Displays Comprehensive information helps to promote sales. Customers are always glad of information about their vehicles. And the ideal place to obtain this is in a workshop or aftermarket sales room.

Small Display: f Convenient display with 24 hooks and capacity for 120 Super plus set packs. Dimensions: 130 x 46 x 21 cm (without place-ment). Order number: 1 987 710 563 Display (stand with 24 hooks incl. back board)Rack: f Convenient rack with 2 shelves and capacity for 36 Super / Super plus standard packs. Dimensions: 57 x 62 x 15,5 cm (without place-ment). Order number: 1 987 710 238 Rack (2 shelves + head board)Large Display: f Visually appealing display with 24 hooks and capacity for 120 Super plus set packs Dimensions: 210 x 58 x 27 cm (without place-ment). Order number: 1 987 710 232 Display (stand with 24 hooks incl. back board)

Plain for all to see: Workshop posters Clear, detailed and perfectly designed to be displayed just where the information is needed – workshop posters from Bosch.

Spark plug faces: Cause and effect fSpark plug design: Technology down to the last fdetail

All you need to know: Info folders In-depth information, clearly presented, on specific topics relating to Bosch spark plugs.

Spark plug folder – provides detailed insight into fthe full range of spark plugs from BoschLow-power engines – everything you need to know fabout spark plugs in low-power engines Gas applications – points to watch when working fwith gas-driven vehicles

42 43

A wealth of promotional and informative material:

Media presence for a well-known name fand brand acceptance A full range of promotional material from fadvertisements right through to catalogs and brochures

Experience Bosch competence live: On factory visits, customers have the opportunity to see test tracks or development centers in action and to gain a personal impression of the expertise of one of the world‘s largest system manufacturers.

Clear, concise information: Catalogs, fold-out list All the products, all the services. Clearly presented for rapid identification of the right item.

Spark plug catalog fSuper plus catalog fSpark plug special range catalog fBosch Duraterm and Super plus catalog fFold-out list for rapid assignment of the right fspark plug to the right vehicle model

Glossary

At a glance: Spark plug facts and figures

Air-fuel mixture / Lambda For complete ignition of the air-fuel mixture in the combustion chamber, the elements of this mixture must be in a stoichiometric ratio. This is the case with 14.7 parts air to 1 part fuel. This ratio is known as „Lambda“. Given a stoichiometric ratio, Lambda is equal to 1.

Air gap Path taken by the spark between the electrodes to ignite the fuel-air mixture in the combustion chamber.

Auto-ignition temperature This is roughly 850 °C. Above this limit auto-ignition can become a problem. The air-fuel mixture may be ignited by overheated components and cause uncontrolled ignition which could damage or even destroy the engine.

Battery-based ignition Use of an ignition coil to generate a high voltage and produce the spark.

Electrode gap The electrode gap is the shortest path between the center and the ground electrode. The voltage is crucial to the electrode gap. If the voltage is too low, sparkover cannot take place.

Insulating paste Provides a seal between the ceramic and the spark plug connector. The use of insulating paste prevents head sparkover.

Insulator The insulator is made of an aluminum oxide ceramic and insulates the center electrode to ground up to a voltage of 40 000 V.

Insulator nose This projects into the combustion chamber and has a considerable influence on the heat range of a spark plug.

Lean mixture The air-fuel mixture contains more air than is needed for ignition. This results in misfiring. Fuel consumption increases while the power output decreases. As of a certain volume of air the mixture is no longer ignited.

Multiple ground electrode Spark plugs operating on the surface gap or surface air gap principle with two, three or four ground electrodes.

Rich mixture The air-fuel mixture contains more fuel than can be burnt. On cold starting, greater quantities of fuel have to be injected to compensate for the losses caused by fuel condensation.

Flashover protection Designed to prevent the high voltage current surge travelling along the outside of the spark plug. For this reason the top part of the insulator is provided with circumferential grooves.

Gasoline direct ignition In this modern process gasoline is injected directly into the combustion chamber of the cylinders under pressure by a common rail system. This permits a stratified mix-ture with less fuel than with conventional injection.

Head sparkover High voltage leakage due to dirt or moisture. Irregular sparkover of spark discharge.

Heat range The heat range is an index of the thermal design of a spark plug. It indicates the capacity of the spark plug to withstand thermal loads based on the balance between heat absorption and dissipation.

Heat shrinking process This produces a gas-tight joint between the nickel-plated spark plug body and the insulator.

Self-cleaning temperature High temperature at which carbon residue is burnt off. This cleans the spark plug.

Shunt Branch of a parallel circuit of electric loads.

Single ground electrode Spark plugs operating on the air gap principle with just one ground electrode.

Sintered-in center electrode In the stoving process the center electrode is permanently joined to the ceramic.

Spark duration The ignition spark duration between the electrodes (approx. 2 ms). This must be maintained long enough for the air-fuel mixture to be ignited.

Stratified charge The air-fuel mixture is prepared such that at the moment of ignition there is only an ignitable mixture (Lambda ~ 1) in the area of the spark plug. The mixture in the rest of the combustion chamber is very lean and barely ignitable (Lambda ~ 10). This improves the efficiency of the engine with regard to emissions and fuel consumption.

Homogeneous mixture For engines with manifold injection. Same Lambda throughout the combustion chamber. Even engines with a lean mixture (large volume of air in the combustion chamber) are operated with a homogene-ous charge.

Ignition The ignition process is controlled by the engine. The ignition system generates a regular high voltage. In the form of a spark, this voltage produces current discharge between the electrodes of a spark plug. This spark ignites the compressed air-fuel mixture in the combustion chamber.

Ignition energy The forward current and the design para- meters of the ignition coil determine the amount of energy stored in the ignition coil and used as ignition energy (ignition spark). The correct ignition energy is important for ignition of the air-fuel mixture, as a high power output and low emission levels can only be guaranteed by efficient ignition.

Inner seal This forms the gas-tight connection between the insulator and the metal body and provides heat dissipation.

Surface gap Path covered by the spark as it travels first over the surface of the insulator tip before jumping to the ground electrode. Along this path it burns off unwanted deposits and combustion residue.

Surface air gap/surface gap Spark paths which can pass through the air and over the insulator. The electrode gap can be reduced by combining mutually independent surface air and surface gaps. This in turn considerably extends the service life of the spark plugs.

Terminal nut Contact between spark plug connector and spark plug center electrode. Passes the ignition voltage to the electrode.

Torque Unit of force for fitting spark plugs.

Type designation The spark plug specifications are contained in the type designation. This shows all the principal features of the spark plug with the exception of the electrode gap.

44 45

Frequently asked questions: Answers from the experts for experts

FAQ46 47

What is the task of the spark plug and why are spark plugs crucial for the life of the engine?The spark plug has to ignite the air-fuel mixture in the combustion chamber of a gasoline engine by means of an electric spark. During operation, spark plugs become contaminated and are subject to wear. The resulting increase in the electrode gap leads to a higher ignition voltage requirement. If the required ignition voltage exceeds the ignition voltage provided by the ignition coil, this results in misfiring.

Is the electrode gap set during production?The electrode gaps are set during production. The electrode gap does not normally need to be reset when changing the spark plug.The appropriate electrode gap for each vehicle appli-cation can be found in the Bosch spark plug catalog.The electrode gap of the spark plug is specified on the packaging.

What is pre-ignition?Pre-ignition (auto-ignition) is an uncontrolled ignition process in which the temperatures in the combusti-on chamber rise so sharply that severe damage to the engine and the spark plug occurs. At full load operation, auto-ignition can occur at the following points:• At the tip of the spark plug insulator nose• On the outlet valve• On the cylinder head gaskets in front• On deposits that become detached

What is meant by engine knocking?Engine knocking is uncontrolled combustion with a very rapid pressure increase.This kind of uncontrolled combustion is caused by

self-igniting parts of the mixture that are ignited without a spark. Combustion occurs significantly faster than normal combustion.Pressure fluctuations with high pressure peaks and high frequencies occur, which interfere with the nor-mal pressure progression. If the combustion pressu-re reaches the walls of the combustion chamber, this produces the metallic knocking noise.Serious engine damage may result if the problem is not rectified in good time.

What is the heat range of a spark plug?When cold, the engine is operated with a rich air/fuel mixture. As a result, incomplete combustion can cause soot, which accumulates in the combustion chamber and on the spark plug.This residue contaminates the insulator nose and produces a conductive connection between the cen-ter electrode and the spark plug shell. This “shunt circuit” discharges part of the ignition energy and reduces the energy required for combustion.The deposits of combustion residue on the insulator nose depends greatly on the temperature and prima-rily occurs below around 500 °C.At higher temperatures, the carbon-containing resi-due on the insulator nose burns and the spark plug cleans itself. It is important to choose the correct spark plug heat range and to ensure that the tempe-rature range of the spark plug remains between 500 and 900 °C. In this range, the spark plug cleans itself but without getting hot enough to cause severe wear to the electrodes due to oxidation and hot gas corro-sion or to result in pre-ignition.

Does anybody check on the appropriate heat range for a particular engine and what are optimized spark plugs?Bosch has developed a new method specifically to reflect the demanding requirements of direct injec-tion gasoline engines.This simulation is the only one of its kind in the world and is used to design virtual spark plugs and visualize the processes in the engine. It also opens up new options for perfect derivation of measuring results and optimization of spark plugsAt critical operating points in the partial load and idling speed range, optimized spark plugs result in:• Increased ignition reliability• Reduced fuel consumption and pollutant emissions• Optimum catalytic converter protection

Can the same spark plugs still be used after alte-ring the power output of an engine?If the power output of an engine has been modified, e.g. on account of a turbocharger, a blower or other systems, the recommended spark plug cannot be used. It may be necessary to employ a spark plug with a lower heat range to compensate for the extra heat generated by the engine. In such cases, Bosch recommends seeking the advice of an engine construction expert to help determine the correct heat range.

What are the recommended replacement intervals for spark plugs?The spark plug replacement interval is generally indi-cated in the owner‘s manual. Bosch advises having the spark plugs inspected once a year and replaced if necessary to ensure optimum engine performance.

To which types of load are spark plugs exposed?Spark plugs may have to withstand electrical, mechanical, chemical and thermal loads.

Electrical requirementsSpark plugs must remain functional under extreme conditions. The ignition process involves voltages of up to 40 000 V and combustion chamber tempera-tures in excess of 1 000°C. Optimum insulation is essential.

Mechanical requirementsSpark plugs must be capable of withstanding alter-nating pressures of around 100 bar in the combusti-on chamber.They must exhibit constant, high mechanical strength under all operating conditions.

Chemical requirementsResistance to chemicals in the combustion chamber and aggressive (corrosive) residue from the combu-stion process.

Thermal requirementsThermal shock resistance (hot exhaust gases and cold intake air-fuel mixture). Good thermal conduc-tion of the insulator and the electrodes is essential for reliable operation.