Spark drops to zero after cranking

[ferocity02]

Been having this issue for awhile. During cranking the spark is correct, around 13 deg. But once it starts running the spark drops to a very low value, ~0-6 deg for less than a second, causing the idle to drop and it almost wants to die. But then the spark ramps back up and the idle flares up also. After a second or two it will eventually find the correct idle speed and base idle spark (24 deg). It does this much worse when cold. It will do it immediately after a flash also so it probably doesn't have anything to do with learned values.

I logged some spark PIDs during startup and ASPARK dropped to almost zero after cranking. There was also spark retard from brake torque management but I don't think it was actually doing anything. While driving, spark matches the high-octane table despite the BTM spark retard.

Anyone know what could be happening? It's a '01 5.3L with a T56 running a 4L60E tune. Please don't suggest I should use a manual transmission segment... I have, and it does not work as well as the auto segment for some reason :ermm: I still had this issue with the manual segment.

Thanks!

[JordanSBC427]

I am also having this same issue, except I get 13 deg while cranking and then while I am idling it is showing about 0 deg of timing....which is not very good. My spark table for P/N is saying I should have anywhere from 7 deg to 18 deg of advance, depeding on ECT etc...

I am going to try and post a thread as well and see if I can get get someone to help figure out what table its pulling the data from and why.

[statesman]

If it's only on cold starts, then maybe it's the catalytic converter light-off.

[joecar]

Look in the STATEnn pids to see if any of those indicate something.

[JordanSBC427]

I don't have cats in the vehicle, fortunately. I will try and check into this STATEnn PID, which exactly are those joe....or what would be a good definition of a STATEnn pid?

sorry.....lacking knowledge.

[joecar]

On the PIDs tab in the scantool, find GM.STATE01, GM.STATE02, etc... on each do rightclick->More Info, you will see that these pids have bit flags to indicate a variety of conditions.

[JordanSBC427]

Ok, I found all the GM.STATE's and the 0 or a 1 indicating on/off, open/closed etc...I assume that I will have to click on these and add them to my PID list while I am doing a log on the truck? Also, Will I be able to observe the condition of each individual digital input or how do I view them exactly?

Thanks.