Hi.
After performing some logging on the E38 used in the Holden VE SS (Pontiac G8 GT), I have determined what is causing some of the poor throttle response issues on the factory tune.
Mainly under light throttle applications, I have noticed that the spark advance when going between Idle Base Spark, Main Spark and Idle Coastdown Spark, is slowly ramped up/down between these tables. For example, when cruising at light load (Main spark table being used), if the throttle is closed, the advance slowly ramps down to the coastdown table value for that rev/load. When the throttle is opened slightly again, the advance does not immediately return to values in the main spark table, but instead are ramped back up very slowly over a period of 1-2 seconds. This also happens when at idle and then opening the throttle - the spark is ramped slowly from the idle table to the main spark table.
This causes a noticeable flat spot in response until the advance reaches the correct value in the main table. I understand that the factory tune may be intended to smooth out things like throttle transitions, however I personally find it annoying and would like to change this operation for a faster response.
Is there a parameter that can be changed to remove this spark ramp up/down between tables? I have already disabled Tip-in limiting and burst knock, which have had no effect. Is there an engine torque management parameter which may be causing this?
Any suggestions would be appreciated.
Thanks.