Strange Adaptive Idle Spark issue
Strange Adaptive Idle Spark issue I've been working quite a bit on getting my idle tune squared away. It's going pretty well except for a strange lack of Adaptive Idle Spark adjustment for around 10 seconds after reving the engine(small or large revs do the same thing). It will use what appears to be the main spark table for those 6-10 seconds, then adaptive idle spark kicks back in. I would really like that adaptive spark to kick right in after going to 0% tps if possible as this is causing the rpm's to hang a while, then go into a small oscilation. It looks like it is still in an idle trim cell (20) and I don't think PE is poping it out of an idle spark control situation (this also happens at throttle blips that are low enough that pe wouldn't engage). Any possiblity of a DFCO spark type interference? I'm almost there.. just need a bit of help on the small details.
Any ideas? Thanks in Advance,
Bryan
Any ideas? Thanks in Advance,
Bryan
Have you tried cutting the running air flow tables to stop the rpm from hanging. It may transition to the idle spark tables quicker if you allow it to pass the idle rpm.
I usually have good luck playing with the IAC decay rates to stop the oscillation following any throttle blips.
I usually have good luck playing with the IAC decay rates to stop the oscillation following any throttle blips.
Thanks for the ideas.
I actually have the RAF pretty dialed in pretty well. It's relatively high beause I've scaled the IAC steps to match the 90mm maf and slight tb set screw opening. I also have a ton of cam overlap. I've matched the desired idle airflow to the acutal maf and dynamic flow. I've got the IAC Steps around 45 on idle which I'm confortable with. **took another look and the RAF is a little high in this log after all.. -.3 to -.5 STIT I'll tweak that down a little. The problem was every time I tweaked the IAC steps/area the desired RAF would change**
I'm on board with your idea about the decay though. (although I'm not sure that it is a ccontributing component to this issue) Once I got the IAC steps dialed in, the decay was a noticably slower. I've bumped it down a little already but don't want to do much more until I can figure out why the adaptive idle shuts off for a while after the throttle rev or blip.
One thig I just noticed in the log.. The Adaptive Idle Air (STIT) is also doing nothing during this 6-10 second period. So, Adaptive Idle Spark AND Air control are shutting off. Hmm.. I don't think there is a decay or hysteresis for adaptive idle & spark is there?
I actually have the RAF pretty dialed in pretty well. It's relatively high beause I've scaled the IAC steps to match the 90mm maf and slight tb set screw opening. I also have a ton of cam overlap. I've matched the desired idle airflow to the acutal maf and dynamic flow. I've got the IAC Steps around 45 on idle which I'm confortable with. **took another look and the RAF is a little high in this log after all.. -.3 to -.5 STIT I'll tweak that down a little. The problem was every time I tweaked the IAC steps/area the desired RAF would change**
I'm on board with your idea about the decay though. (although I'm not sure that it is a ccontributing component to this issue) Once I got the IAC steps dialed in, the decay was a noticably slower. I've bumped it down a little already but don't want to do much more until I can figure out why the adaptive idle shuts off for a while after the throttle rev or blip.
One thig I just noticed in the log.. The Adaptive Idle Air (STIT) is also doing nothing during this 6-10 second period. So, Adaptive Idle Spark AND Air control are shutting off. Hmm.. I don't think there is a decay or hysteresis for adaptive idle & spark is there?
Last edited by FDLS6; Apr 30, 2010 at 04:41 PM.
