I am trying to figure out what is causing the stall on this Jeep. I say it is random, but honestly so far it happens about 5-10 minutes after cold startup. Then will not restart unless it sits for a few minutes. I have not been able to have it happen to me yet, so I could not do the normal checks while it is not starting. The few times it has happened have been at a stop light or in a drive through. After restart then it has not happened again until after a cool down period.
I am expecting it to be the crank positioning sensor, possibly fuel loss, or the ECM solder joints (not sure 2000 model still had that issue). But I do not want to throw parts at it because it is my daughters car and I want to be confident it is fixed before she is driving it again.
I logged it idling from cold for 10 minutes. Idle was solid for the entire time except around 6m20s it dipped hard into the 400's and caught itself. Fan was not kicking on or anything to cause it. Viewing the log I see the rpm registering and the O2 is showing it stayed lean for a bit, so leaning towards fuel now. If crank sensor, the rpm would go to 0 right, since that would be how it gets rpm. If I can get it to stall in the morning after another cool down and not start then maybe I can figure out more. I do have a fuel pressure gauge hooked up under the hood, but was watching dashboard when the dip happened.
The rpm dip is in the middle of the log. The last few seconds of the log is me shutting it off and restarting.