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'88 MJ w/ 4.0L 5spd idling problem


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On start up it idles fine If drive down the road a little bit and then push in the clutch to come to a stop it dies like turning of the switch, but it always starts right back up and drive fine until I need to stop again. Funny thing is it doesn't do it all the time every onvce in awhile it will come down to an idle and stay running. what would cause this? I've done quite a bit of searching but have come up with nothing. :wall:

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It sounds like he is talking about the idle speed control motor and it is attached to the front of the throttle body. As you stand in front of the jeep and look at the motor/throttle body it is the one one the left, held inplace with 2 torx screws and has one wire connector.

 

When mine went bad it kept the engine reving at 2800 rpm's. I pulled mine out and it had alot of crud around the shaft that stopped it from moving. I bought a new one and it runs great now. Ithink the new one was around $40-50.

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It sounds like he is talking about the idle speed control motor and it is attached to the front of the throttle body. As you stand in front of the jeep and look at the motor/throttle body it is the one one the left, held inplace with 2 torx screws and has one wire connector.

 

When mine went bad it kept the engine reving at 2800 rpm's. I pulled mine out and it had alot of crud around the shaft that stopped it from moving. I bought a new one and it runs great now. Ithink the new one was around $40-50.

 

Who has them(I haven't really looked yet)? I'm having the same problem accasionally and plan to replace it. I've cleaned it several times over the past few years.

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vac leak in the booster hose?

 

At the Brake booster? Sorry for my lack of intelligence on this, I'm more knowledgeable on Volkswagens than jeeps at this point. But I'm trying to learn.

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It seems to be something besides the brakes. I can be driving down the road push in the clutch and it sometimes will die until I change gears and let out on the clutch again. but most of the time its only when I come to a stop. but is always starts back up and I can go on down the road.

 

I have poured some Seafoam down the TB while running and then let it set a while before cranking it up. It rans better and smoother, but hasn't got rid of the dieing thing. :mad:

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It seems to be something besides the brakes. I can be driving down the road push in the clutch and it sometimes will die until I change gears and let out on the clutch again. but most of the time its only when I come to a stop. but is always starts back up and I can go on down the road.

 

I have poured some Seafoam down the TB while running and then let it set a while before cranking it up. It rans better and smoother, but hasn't got rid of the dieing thing. :mad:

 

I feel your pain. My MJ is an 88 4.0 5spd like yours and I had the random rare stall only when coming to a stop and pushing in the clutch, just like you describe.

 

My truck idled at 500 RPM even on cold start. I tried cleaning the IAC with no change (it was filthy but not stuck). I have no vacuum leaks (would idle higher if there were I would think).

 

Finally, I carefully cleaned the whole TB with TB cleaner. I put plastic bags with rubber bands around the TPS and avoided getting any cleaner on it. This seemed to help as it hasn't happened since. The truck seems to idle at 550-600 rpm now. I did the 97+ XJ valve cover at the same time, so not sure if that had some to do with it.

 

HTH :cheers:

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I found that Napa and advanced auto have the idle speed control motor. Look on the websites for the auto parts stores near you, many have a search feature by vehicle to find parts they have/carry. If you stand in front of the jeep it is on the front left of the throttle body. There is one wire connector and held on with 2 torx screws. It would be best if you take the old one along to compare because the counter person could grab the wrong one (different wire connector) and since it is an electrical part, unreturnable.

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Thanks for the tips info guys. But sadly I have to change things a little.

 

I Hit a deer with comanche and killed the radiator and whole front cap on the drivers side, fender, header, grill frame, whole headlight assembly, and bumper are done for.

 

So now I have to put to the side and hope I can the parts I need to fix it. I had just got it back on the road about a month ago after a long wait and now this. :cry:

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