After datalogging a startup to dial the idle, I noticed that the engine runtime started at 1600, so the car is acting like it's been running and it's causing a stall on cold starts. Any idea what this could be? Bad ECM maybe?

 

Hi

Have you tried turning the engine off, letting it sit for a few minutes, plugging ALDL cable back on car/laptop, turning the key on and establishing connection? What is the ecm displaying for ENG RUN time?

If ENG RUN time is not zero, try resetting ecm by unplugging battery for a few seconds and redo the same test. You should get ENG RUN time = 0

If you do get 0, start the car and datalogg for a few secs, then turn off the engine. Note the ENG RUN time at the end of run.

Unplug ALDL cable after turning the engine off (remove key)

Redo the first test. If ENG RUN time is not zero, but equal to time at the end of your last run, you have a problem (IMO)

Could it be the ecm? I don't know.
It's pointing towards the ecm staying on more than 11.3s (like your BIN) after key turned off and removed.

Hopefully someone will chime in with a possible cause.

EDIT: I believe you have the '7165 ecm with $6E mask and AUJM BIN and using TunerPro, right? That's helpful info for whoever wants to chime in.

EDIT2: The reason it's causing the engine to stall is because, the ecm skips the Start-up Open Loop Commanded AFR and goes directly to OL Commanded AFR (14.03 instead of 10.9). That makes the real AFR too lean when engine is cold. Again, good info to know if someone wants to chime in.

 

https://www.thirdgen.org/forums/tpi/...ime-reset.html