The GPT system can overwrite an array of variables with its output, however, there are certain main GPT variables that should be used to ensure continued safe operation of the ECU. For example, overwriting the "SYNC STATUS" would cause the ECU to lose sync and should be avoided.


If you are using anything other than PWM outputs, then the following key GPT variables should ideally be the only ones written to to effect ECU fuelling/Ignition/boost operation.


Variable Name

Function

Notes

Inj PW GPT Trim [2095]

Trim Injection (fuel) by the amount assigned. (multiplier)

If you assign this to 0.5 then 50% of the final fuel will be delivered. If assigned to 1.78 then 178% of the final fuel value will be delivered (up to physical limitations ie Injector size)

Lambda Target AFR GPT Trim [2096]

Will trim the target AFR by the set amount (multiplier)

If you set this to 1.1 and the target AFR is 13, the resultant target AFR will be to set to 14.3 (13+1.3). Use this as a closed loop target modifier ie for Nitrous etc.

Ign. Adv. GPT Add [2097]

An additive modifier to the ignition timing in degrees.

You can add/subtract a value to the final ignition advance using this value. ie if this is computed to 3.2 and the current ignition angle is 10, the final ignition angle will then be 13.2.

Boost CL GPT Trim [2098]

A multiplicative trim of the Closed Loop Target Boost value.

IF the current closed lop target from the boost control system is 150Kpa, and this GPT value is set to 2, then the closed loop target boost will become 300Kpa