idel probelm
#3
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Year: 1993
Model: Grand Cherokee
Engine: 4.0L I6
My ZJ did the same thing when the IAC was bad, it was running ok but after i did remove the battery for some time the ECU got reset and then i didnt know how to use the bad IAC. I replaced the IAC and TPS, still a litle problem and replaced the TPS againg and then everything was ok. I think there is a lot of bad quality parts out there, the first TPS i tried fell apart. I also cleaned my TB since it was full of "dirt"/black oil.
#5
Caracticus Potts The Mod
you don't mention if it's the 4.0L or the 5.2L. Vacuum leaks can cause the idle to fluctuate and the 5.2L will stall if the IAC can't control minimum idle air flow. In either case it would not be uncommon for a replacement part to be faulty, i.e. the IAC or TPS that you said you replaced.
In regards to the IAC, a battery disconnect or reset min air flow and IAC relearn should be done when ever the IAC or TPS are replaced. Best way is with a suitable scanner, however disconnecting the battery terminals and momentarily touching the two cables together for a few seconds will clear all the ECM/BCM data and cause the ECM/PCM to perform the relearn, however transmission and fuel trim data will be lost doing that and it will shift funny until the TCM relearns the shift pressure points.
In regards to the IAC, a battery disconnect or reset min air flow and IAC relearn should be done when ever the IAC or TPS are replaced. Best way is with a suitable scanner, however disconnecting the battery terminals and momentarily touching the two cables together for a few seconds will clear all the ECM/BCM data and cause the ECM/PCM to perform the relearn, however transmission and fuel trim data will be lost doing that and it will shift funny until the TCM relearns the shift pressure points.
#7
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Year: 1995
Model: Grand Cherokee
Engine: 4.0 with all of the noise and clatter
The 5.2 V8 has a plate with a gasket on the bottom of the plenum, the gasket can get blown out and then you will get an internal vacuum leak. It can also suck oil into the intake and cause an oil consumption problem. The best way to check it without pulling the intake manifold off would be with a smoke machine. Pump smoke into the intake, if you have smoke coming out of the oil fill cap, you gat a leaking plenum plate. Make sure to cap off the PCV nipple on the manifold first though.
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#9
Old fart with a wrench
If you've got the time and a place to work, pull the intake off and check it out.
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