High Idle but only in park
#1
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Year: 1987
Model: Cherokee
Engine: 4.0
High Idle but only in park
It takes a bit to start and then idles like crazy in park. But as soon as I put it in gear it smooths out to normal. The inside of the intake manifold is pretty dirty from the blow-by, but that is fixed now. It has been doing it since I got home. And there is no problems that I have noticed while driving. It just happens in park.
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Year: 1993, 1994
Model: Cherokee
Engine: 4.0L HO
Probably the same in Neutral, when there is no load on the engine.
I'd pull the throttle body and give it a good cleaning. A new base gasket is like $2.50, a can of carb cleaner is $4, and a cheap toothbrush can go a long way. Specifically, get the ICV ports cleaned out. If it's sticking open a little, you'll have a high idle. If it's sticking closed, you'll have hard starts.
Did wonders for the starting/idle on mine.
I'd pull the throttle body and give it a good cleaning. A new base gasket is like $2.50, a can of carb cleaner is $4, and a cheap toothbrush can go a long way. Specifically, get the ICV ports cleaned out. If it's sticking open a little, you'll have a high idle. If it's sticking closed, you'll have hard starts.
Did wonders for the starting/idle on mine.
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Year: 1990XJ/1989MJ
Model: Comanche
Engine: 4.0L Renix
Yes it is a Renix and has a TPS and an IAC also called the Idle stepper motor. I would bet the IAC has never been off to be cleaned. If you take it off(T-10 torx) be very gentle with the idle pintle. That is easily damaged. If cleaning the IAC does not improve your idle then post back up and we can then try some more complicated fixes.
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Year: 1993, 1994
Model: Cherokee
Engine: 4.0L HO
Yes it is a Renix and has a TPS and an IAC also called the Idle stepper motor. I would bet the IAC has never been off to be cleaned. If you take it off(T-10 torx) be very gentle with the idle pintle. That is easily damaged. If cleaning the IAC does not improve your idle then post back up and we can then try some more complicated fixes.
Just as a note, when I cleaned the IAC on my '93, just cleaning the plunger didn't help. I had to remove the entire throttle body and clean the chamber out, it was full of a tar-like substance.
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Year: 1990XJ/1989MJ
Model: Comanche
Engine: 4.0L Renix
Hope it runs well now Code.
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#8
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Year: 1993, 1994
Model: Cherokee
Engine: 4.0L HO
Wasn't a big issue, unhook two electrical connections, unscrew like 8 torx bolts, and a new gasket.
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Year: 1990XJ/1989MJ
Model: Comanche
Engine: 4.0L Renix
They have a tendancy to leak at the gasket surface and will often run worse than before the cleaning. That's why I always suggest the Seafoam to keep from breaking the gasket seals. You either were very diligent in cleaning the two surfaces or you got lucky. Either way I'm glad it is running well now.
#12
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Year: 1987
Model: Cherokee
Engine: 4.0
When I bought it I checked the air filter first to see how bad the blow-by was, and it had a bit of oil in it. So now that line just goes into a cut-up bottle by the air intake. I pulled the throttle body off and cleaned it out and the IAC. But there is still a buttload of tar in the intake manifold. I want to seafoam in but it would be hard to do on post with the reported white cloud that comes out. But also I didn't replace the gasket to the throttle body. I know my fault. So do you think it might be cause the gasket is pretty much crap. And I also snagged a multi meter today to take care of the TPS.
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Year: 1993, 1994
Model: Cherokee
Engine: 4.0L HO
When I bought it I checked the air filter first to see how bad the blow-by was, and it had a bit of oil in it. So now that line just goes into a cut-up bottle by the air intake. I pulled the throttle body off and cleaned it out and the IAC. But there is still a buttload of tar in the intake manifold. I want to seafoam in but it would be hard to do on post with the reported white cloud that comes out. But also I didn't replace the gasket to the throttle body. I know my fault. So do you think it might be cause the gasket is pretty much crap. And I also snagged a multi meter today to take care of the TPS.
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Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
When I bought it I checked the air filter first to see how bad the blow-by was, and it had a bit of oil in it. So now that line just goes into a cut-up bottle by the air intake. I pulled the throttle body off and cleaned it out and the IAC. But there is still a buttload of tar in the intake manifold. I want to seafoam in but it would be hard to do on post with the reported white cloud that comes out. But also I didn't replace the gasket to the throttle body. I know my fault. So do you think it might be cause the gasket is pretty much crap. And I also snagged a multi meter today to take care of the TPS.
Anyone else want it, do the same.
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