Diplomat1

I have got a lead on my high idle issue driving it the other day and I finally got a p1294 code. Its a 2002 grand Cherokee 4.0.If some of your guys remember I had another thread with the high idle issue I replaced the throttle body with a junkyard one cleaned it up also tried 3 aftermarket iacv and couple tps sensors with no luck. I then traced the wires from the iacv connector and found continuity on all 4 to the pcm connector. All wires are good and none of them are open or shorted. That leaves the pcm which is new from a computer repair place I found on eBay. Just in case I they are sending me a new pcm to try and see if it works but I don't think it will. Here is a video of it driving. In the video my foot is off the gas pedal car is in neutral and it's coasting. The rpms flucuate by itself as you can see. Is this an iac/pcm issue or a vacuum leak issue? I have checked all the hoses sprayed carb cleaner everywhere and no luck. Also could a leak around the evap canister cause this kind of issue? Any help would be great thanks

Cherryokee

My "aha" moment happened when you referred to aftermarket tps and iac units. I have little-to-no faith in those. If you think you have a vacuum leak then you must go into search mode. Can you do a smoke test or maybe, with a helper, spray carb cleaner at areas prone or suspected to vacuum leak while monitoring for surge in idle rpms?

dave1123

Open the tank valve on a propane torch and play the gas around. It's a lot cleaner than using carb cleaner. It's also plastics safe. I ruined my TPS by spraying Seafoam directly down the throttle body. It leaked thru the seal into the body of the TPS.