trogdune Posted March 3, 2023 Share Posted March 3, 2023 Hi there, recently my comanche will start reving high randomly. Doesn't happen often but once and a while the RPMS will climb and I'll have to shut the truck off and restart then goes back to normal. Is it an Air filter issue or a sensor of some kind? Any help greatly appreciated. Link to comment Share on other sites More sharing options...
cruiser54 Posted March 3, 2023 Share Posted March 3, 2023 Link to comment Share on other sites More sharing options...
Classy Comanche Posted March 3, 2023 Share Posted March 3, 2023 Well. We don't exactly know what engine you have. I'll assume it's a 4.0 I had a issue with high revs. I would start my truck and it would be around 1000rpms and I would guess it would go up to around 1200 for cranking. If it is indeed a 4.0 you could try cleaning your butterfly valve in your throttle body. It may be sticking open or not closing all the way. It could be your throttle position sensor or idle air control valve. Me and the guy working on the truck chased this for a while so I just threw a new TPS, IAC and went ahead and did a new O2 sensor and she purrs like a kitten now. It also wouldn't hurt to check for vacuum leaks, loose vacuum hoses or disconnected ones Link to comment Share on other sites More sharing options...
cruiser54 Posted March 3, 2023 Share Posted March 3, 2023 We need the proper info first. Link to comment Share on other sites More sharing options...
pizzaman09 Posted March 4, 2023 Share Posted March 4, 2023 We do need to know what engine you have. That said, header bolts are known for being loose on the 4.0L. If you have a 4.0, make sure they are all tight. These are the nuts and bolts that hold the intake and exhaust to the head. You may even find a few missing. Link to comment Share on other sites More sharing options...
trogdune Posted March 5, 2023 Author Share Posted March 5, 2023 I ended up just cleaning the throttle body and AFS as they were both gunked up pretty bad. Hopefully that will solve the problem. I'm working on a 89 4.0 Pioneer Manual 4x4 Link to comment Share on other sites More sharing options...
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