Long Term

The main function of Long Term Adaptive is to make fuel corrections that permit Short Term Adaptive to hover around zero. In order to maintain correct emissions throughout all operating ranges of the engines, a cell structure based on engine rpm and load (MAP) is used.

There are 26 cells used for the NGC. Two of the cells are used only during idle, as determined by throttle position and park/neutral switch input. The other cells each represent a given off-idle manifold pressure and rpm range.

After the vehicle has reached full operating temperature, short term correction factors will update Long Term Adaptive Memory cells based on vehicle load (RPM/MAP) to allow the Short Term Adaptive value to be brought back to near zero. Once this correction factor is updated in the memory, it will be used by the PCM under all operating conditions, open loop and closed loop. However, the values stored in the Long-term are updated only after the vehicle has entered long-term closed loop at full operating temperature. This is done to prevent any transition temperature or start-up compensation form corrupting long term fuel correction.

Long Term and Short Term Adaptive can each change the pulse width by as much as ±33% for a maximum total correction of ±66% from base pulse width calculation. Long Term Adaptive values are used during both Open Loop and Closed Loop operation.