98 ZJ dies during warm-up
1998 Grand Cherokee 4x4 5.2L
Jeep starts fine when engine cold. Runs great actually.
When operating temp reaches about 150F the Idle Air Control starts to open and the engine rpms start dropping until it dies. Will not restart when warm.
I have to wait until the engine cools completely to repeat the above cycle.
No codes are thrown.
This is what I know:
Fresh fuel, good pressure.
Good spark throughout, even to the point of dying.
Fuel injectors are audibly working.
If I choke off the intake hose with my hand, it wants to recover.
It doesn't miss or run rough, just dies slowly.
Throttle body and attached sensors cleaned with new TB gasket.
Coolant temp switch is new and resistance of sensor corresponds correctly to approximate temp when cold and warm. This sensor throws a code when disconnected. Wiring to PCM good.
Manifold air temp sensor resistance also corresponds correctly. This sensor throws a code when disconnected. Wiring to PCM good.
Upstream O2 does not throw a code when disconnected. This makes me believe the PCM is not making it to the OPEN/CLOSED loop switch.
PCM connectors in good condition. No loose pins, no corrosion.
Map sensor gets 5volts like it should.
I am using the factory service manual for all my checks.
I have not messed with the Crank Sensor. It appears to be working based on how smooth it runs when cold. Of all sensors or parts I have ever changed or tested on any vehicle, this has got to be the worst placement of anything I have ever seen.
Any help is appreciated. I don't want to throw parts at it until I have all testing exhausted.