Nistune NEO ECU Tuning

8/17/2019 Nistune NEO ECU Tuning

1/13

Copyright Nistune Developments 2014


2/13


3/13

Boost Sensor Usage

NEO equipped ECUs use the boost sensor for several purposes:

(a) MAF compensation

Resizing MAFs using the NEO ECU can result in mismatched atmospheric pressure compared to expectedmeasured ECU load measured by the MAF sensor.

MAF sensors convert airflow to voltage and the Voltage Quantifer converts this into a value used to calculateTP = (VQ airflow value / RPM) x K constant

Upgrading to a larger flowing MAF sensor will subsequently increase the total theoretical pulsewidth (TP) sinceK constant (TP injection multiplier) is increased. The boost sensor compensation for MAF voltage can have atemporary effect at initial acceleration, sometimes resulting in delayed acceleration.

Resolution 1: Upgrade injectors

When resizing to larger injectors, the reduction of K constant can offset the TP increase when upgrading theMAF sensor. Suitable injector sizes about 700CC with Z32 MAF (98 octane) or 1000CC (E85) prove to be asuitable combination.

Resolution 2: Disconnect MAP sensor

It has been found that removing the boost sensor connection results in using a default value and reduces theeffect of MAF sensor upgrades. Disconnecting the boost sensor will result in the following DTC:

This has no effect but will trigger the check engine light (CEL). In expert user mode you can disable DTC

filtering for the boost sensor and remove the CEL.

(File > Configuration > User Mode = Expert)

Future updates to Nissan firmware will allow MAF and injector resizing without affecting TP (via K constant).


4/13

(b) Over boost limitation

The boost sensor is used for over boost fuel cut operations performed by the ECU. These tables havereplaced the 'TP load limit' tables used in older Nissan ECUs

The tables are specified in millivolts which is the measurement of the boost sensor5100mV = 18 psi4340mV = 12 psi

When using the factor boost sensor, when the boost reaches the limit in the table the ECU will start a counterand once the counter has reached the specified value (default value of 10), the ECU will perform a fuel cut(boost cut)

Increasing the values of these tables to a maximum of 5100 millivolts will work upto 18psi for safely limitingboost levels.

Above 18 psi to avoid the fuel cut increase the counter to increase the time at over 18psi before cutting fuel(maximum of 255 will effectively disable the cut completely)

Important note: When the boost sensor is disconnected, and there is a Boost Sensor DTC fault code, theECU will instead use the TP limit tables and counter


5/13

These tables work similar to earlier ECUs when there is no boost sensor available. The current TheoreticalPulse width (TP) load is compared against the table value for the given RPM. A counter increases upto thelimit and then a fuel cut is performed by the ECU

Increase the values in the limit table to remove the injection cut when the boost sensor is not used.


6/13

(c) Reporting current boost level

Nissan consult will report the current boost level as a voltage (which can be converted to PSI and is displayedin Nistune from version 1.2.14 upwards)

Boost Pressure Sensor Gauges (view from Knock Warning panel)

If the boost sensor voltage exceeds the specified max voltage the Boost Sensor DTC code will be raised. This

is about 16-17psi

Below 60mv the DTC is raised (primarily for detecting a disconnected boost sensor). Note setting to 0 will notclear the DTC code if the boost sensor is disconnected

Above 4840mv the DTC is raised. Increase this to 5120mv to increase to 18psi before the DTC code is raised.If you are going above 18psi then disable the boost sensor filter flags


7/13

Fuel maps

NEO equipped ECUs now use two separate fuel maps. These function differently to earlier Nissan ECUs

The primary fuel map no longer uses the 'O2' feedback flag overlay over the map like used with earlier NissanECU implementation

Values equal 128 indicate the closed loop area of the fuel mapValues above 128 command adjustment to the base fuel mixture. Increased values result in additional fueling


8/13

AlphaN/Increase Fuel (vs TPS)

The Alpha/N table functions the same as with earlier ECUs. The TPS voltage is compared against the tablevalue for the current engine RPMs

If the throttle position exceeds the current table value then the last column of the fuel map is used instead ofthe map traced cursor position.

Take note of the current TPS cursor value and the maptraced cells in the Volumetric Efficiency (VE) map(covered next page)

Note: Take care whilst making adjustments to the fuel map. Any adjustments not affecting the ‘injection time’and subsequent AFRs should be observed, where the TPS is higher than values in this table

Either:(a) Increase the TPS voltage levels in this table to use the full fuel map. Then tune the fuel map

accordingly, keeping in mind the VE map may reference values below the threshold in this table

(b) Adjust the fueling using the last column value of the fuel map. This column is used when TPS exceedsthe voltage values in this table

(Tune for safest AFRs in the event of high/full throttle and maximum boost)


9/13

Volumetric efficiency

Table is used in addition to the fuel map to trim mixtures based on TPS vs RPM scaling. VE maps are usedadjust enrichment based on TPS position for all later model Nissan ECUs

TPS Voltage Quantifier

TPS is calculated firstly by converting TPS raw voltage to a TPS reference position

The TPS reference position is then divided by RPM and used to reference the VE map index table.

VE Map Index table

Boost sensor available: The value in this table is then multiplied against the boost sensor tableBoost sensor not available: Value is divided by twoThe calculated value is used to index the VE map


10/13

VE Map Boost Index table

The values in this table are a percentage multiplier against the values in the VE map index table. For examplethis table is indexed with current boost voltage of 3840mV (3.8V)

Take 110 from the previous table x 76.5% = TPS VE index value of 83.

So as boost increases the reference to the VE table increases to the right.

Fuel Volumetric Efficiency Map

These maps are used in conjunction with the fuel (and effectively Alpha/N tables where TPS value exceedsthe table value and uses the last column of the fuel map)


11/13

Horizontal indexing takes the TPS index table value and multiplies against the boost multiplier value. Forexample, the TPS index table value (above) of 110 determined then divided by 50% and used to referencecolumn 96-112 in the VE map.

The TPS position is correctly traced from Nistune 1.2.10 versions upwards by direct reading internal ECUmemory. The trace is subsequently not available in normal consult (stream mode) and will update slower thenother gauges.

To enable the TPS position in stream mode, Nistune 1.2.54 versions upwards must be used.

This will add an extra parameter to the factory consult table 'Adjusted TPS VE index' at consult registerlocation 0x19 (Reserved by Nissan). To add the parameter, connect to consult which will add then register.Then disconnect and reconnect to see the parameter added to the list. Tick this item to get tracing in streammode.

Tracing display shown below as VE/TPS:


12/13

ABS / TCS Disabling Functionality

When using NEO ECUs in other vehicles without the supporting ABS and TCS equipment, fault codes will beraised and vehicle operation may be affected

It has been found during recent investigation into the NEO ECU program code that disabling filter flags for

these features will prevent the ECU code from calling those functions

Unticking both of these items will disable the Code 44 (ABS/TCS comms circuit DTC error)

Unticking both of the motor throttle circuit will remove the Code 46 (Throttle Motor Sensor DTC error)


13/13

Feedback Control Flags

Feedback control flags have changed for this ECU. These are available from version 1.2.14 onwards

Knock analysis can still be disabled and disabling closed loop short term uses a different register (not tested atthis time). Internal Nissan diagnostics (not recommended for customer usage) have been added forcompleteness only

Nistune NEO ECU Tuning

Documents

Transcript of Nistune NEO ECU Tuning