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low idle coincidence?

xjwisconsin

NAXJA Forum User
My 88 4.0 5spd, 229,000 miles... edit (As far as I know the TPS, AIC, EGR ect are all original)
I have a high idle aprox 2000 RPMa almost always. To be honest I have not taken the time to get a voltmeter out and start testing things, but I did clean out the throttle body and clean up the air idler this fall. I have noticed though that after driving around in the rain or if there is alot of humidity, such as the thick ass fog we had here last night, the idle will drop noticably. Sometimes it drops as much as 1000 RPM.
Now without having any real data to go off of does anyone have a guess as to what is going on? Is the humidity/ water really doing something?
thanks for the ideas
 
xjwisconsin said:
My 88 4.0 5spd, 229,000 miles... edit (As far as I know the TPS, AIC, EGR ect are all original)
I have a high idle aprox 2000 RPMa almost always. To be honest I have not taken the time to get a voltmeter out and start testing things, but I did clean out the throttle body and clean up the air idler this fall. I have noticed though that after driving around in the rain or if there is alot of humidity, such as the thick ass fog we had here last night, the idle will drop noticably. Sometimes it drops as much as 1000 RPM.
Now without having any real data to go off of does anyone have a guess as to what is going on? Is the humidity/ water really doing something?
thanks for the ideas


from my own expirience with my 87 4.0, I would say that your TPS is bad. If you have an autozone near you, the sensor is about $90. My Jeep reacted to weather changes too. It seemed that my idle dropped in cold weather. so that's the opposite of your rig. But i would try the TPS first. And for a side note: if it's not the TPS, autozone is good about taking stuff back, and the installation is not that hard. hope this helps you out.
 
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