3800 Timing Issues

[LNorton]

I have never experienced this problem before. The car has stuck right to the timing tables in open loop or closed loop.

I also changed every sensor on it except the O2's. Have also been through 3 ICM's and sets of coil packs.

What would cause the timing to act this way? It should be at 40 at idle and 28 everywhere else per my tables.

Any ideas?

Log, Tune & Config attached

[bilemke]

I haven't tuned or looked at the stock programming for many of the non-Wbody 3800's, but is 40* of timing advance at idle really normal?

[LNorton]

This is by no means a stock tune. And yes, 40* of timing at idle. It likes it and I have always run it this way.

[mrcleansmirc]

when you type 40 into the timing tables, that is pretty much the maximum you allow, there are more variables that affect the timing. just cause you typed 40 doesnt mean it will run it all the time.

[LNorton]

when you type 40 into the timing tables, that is pretty much the maximum you allow, there are more variables that affect the timing. just cause you typed 40 doesnt mean it will run it all the time.

Umm.... I did happen to ask WHY

[bilemke]

High Octane Spark is not the max allowed spark.. It is simply the base.. There is TCC/EGR/ECT/IAT modifiers just to name a few. Not all of those modifiers subtract timing. Some can add to the base timing seen in High Octane Spark..

40* at idle is crazy high.. What have you done to that 3.8 to warrant the high idle advance?


What is with the afr switching to 14.40 instead of 14.7? You running open loop or forcing open loop for a few moments?

[LNorton]

What is with the afr switching to 14.40 instead of 14.7? You running open loop or forcing open loop for a few moments?

Not forcing open loop. I am very confused withthis problem. I can't exactly explain why it is comanding AFR at certain points or why the timing goes nuts.

All the modifier tables we have available to us are zeroed out.

[bilemke]

I would almost say it is going to open loop without you.. The o2 sensors are not switching, plus that low afr at idle/cruise.. Maybe add a couple of status bits to your scan to confirm if it is really closed loop when the odd afr/tming is occurring.. Could be pcm thinks o2 sensors are not switching enough and it is falling back to open loop..