This guide offers useful hints and suggestions for tuning Nissan and Infiniti vehicles. Its aim is to explain the functionality of Nissan/Infiniti-specific parameters rather than be a full tuning guide.
Airflow Parameters
Characteristic Coefficients
Some of the sensors relating to air/pressure measurement rely on a linear first-order differential equation to come up with their transfer functions. Instead of a table to define different voltage inputs and their corresponding values, they will set a constant characteristic coefficient to define the curve. By applying Laplace Transform you can come up with the final defining equation.
WOT Fill Up Efficiency IAT Compensation Coefficient
This table defines volumetric efficiency calculation compensation values for a given intake air temperature range while at wide open throttle. To obtain the output volumetric efficiency, take the calculated volumetric efficiency and multiply it by this value (the volumetric efficiency shown in the scanner already has this adjustment applied). Adjusting this table has a direct effect on any table that uses volumetric efficiency in its cell lookups.
Throttle Estimated Torque Switch
Nissan has a couple throttle models. The most common one that is turned on from the factory centers around a torque demand (these tables explained later on in the guide). This is the master switch that controls whether or not this logic is used. By turning this off, the ECM will ignore the throttle related torque tables and give you a close to linear APP to TP relationship.
Open Area to Target Throttle Open Degree Conversion
As part of its airflow calculations, the ECM estimates the actual opening area of the throttle body based on the current throttle angle. Normally it is only advised to change this table with changes in throttle body sizes.
VVEL (Variable Valve Event and Lift) Tables
Nissan's VVEL system is used to control the valve duration and lift. It works in conjunction with the variable valve timing system. The duration measurement begins at the point the valve opens to the point of maximum lift. While the ECM itself sets the valve duration, it's the VVEL control module that will control the stepper motor that determines the desired shaft angle. It's important to note here that increasing or decreasing the valve duration will also increase/decrease the valve lift respectively. If the vehicle you are tuning is equipped with VVEL, the tuning of these tables is simple, increase the value for more duration/lift, decrease for less. You are provided with Min/Max limit maps, normal driving conditions maps and a WOT map to adjust VVEL duration/lift. For the other tables, it is not recommended that they be adjusted unless the VVEL system hardware is physically adjusted.
Fuel Parameters
Cranking Injector Pulse Width
There are 6 main tables that control cranking injector pulse. Cranking Enrichment and Cranking Injector Pulse Width 1-5 all influence the final cranking injector pulse width. It is unknown at this time at what point each map is used, so it?s recommended that you increase/decrease these (Cranking IPW 1-5) at equivalent percentages.
Injector Flow Rate Multiplier
One of the constants that the ECM uses in order to calculate output injector pulse width is the injector flow rate multiplier, which has units of seconds per kilogram. The concept behind what this does is simple, increasing its value increases the pulse width output, while decreasing its value decreases the pulse width output. It's only recommended to change this value for a change in injector size. If you do have a change in injector size, a good value to start at would be to decrease the multiplier at an equivalent percentage to the injector size change.
Period Control
One of the more interesting things about Nissan is their oxygen sensor feedback logic. Part of the feedback system utilizes period-based feedback. This system uses a sine wave and oscillates around a stoichiometric equilibrium point. More information can be found by reading this paper: https://ieeexplore.ieee.org/document/5531230
Open Loop Target Lambda
This table is straightforward, when the vehicle is in open loop this is the lambda value that the ECM will attempt to target. Tuning tip: If you are unfamiliar or unaccustomed to looking at lambda values, by clicking the lambda symbol in the upper right-hand corner you can toggle between assumed stoichiometric values. Alternatively, you can right click on the table to toggle between units.
Spark Parameters
Trimming Adjustment
The trimming adjustment map is going to be your main map that you use for timing adjustments. You may have seen this labelled before as Main Timing, Combustion Duration, etc. While increasing/decreasing the values of this map respectively increase/decrease the timing value, there isn't necessarily a 1:1 correlation between degrees in this map and timing changes, especially for VVEL equipped vehicles. The final timing adjustments are made based on VVEL and knock sensor feedback. In the event of knock detection, for select cells in the upper RPM/Load range the ECM will begin to blend the low detonation and high detonation tables. Non-VVEL vehicles have a much greater degree of control over the timing using this map.
There are separately labelled timing maps for both low/high detonation. During testing it was found that these timing maps aren't active all the time, and the exact activation mode is still unknown.
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Originally Posted by Mark@HPTuners
