crazy idle
#1
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Year: 2000
Model: Grand Cherokee
Engine: 4.0
crazy idle
i have a 1990 4.0 stock cherokee automatic. I have a weird problem with the idle that does not happen all the time. I was driving home, came to a stop light and and when I hit the brakes the truck stayed at about 2000 RPM. I through it in neatral and it jumped to about 3000rpm and I could not get it to idle down.I turned it on and off several times with not luck, it hit about 3500 rmp at one point. it has done this several times in the past month. I cleaned the throttle body and all the sensors hooked to it. I have not had this problem again, but it seems to still be idling high. about 1200 to 1500 in park around 900 to 1000 in park. the weather is usually damp or colder when it has happened. is there any sensors i should check. truck has about 216000 miles on it.
#2
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Year: 88 limited
Model: Cherokee
Engine: 4.0
When My 88 did the high idle thing I unpluggsd the tps and plugged it back in ,that usually dropped the rpms down to idle. I then had to change the tps do to it going bad. You can try it to see if it helps .
#7
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Year: 2001
Model: Cherokee
Engine: 4.0
Pull the IAC and gently clean it with some carb cleaner and a toothbrush. Fixed my crazy idle on my 88..also see if you hear a hissing from a vac leak..
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#9
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Year: 1990
Model: Cherokee
Engine: The venerable 4.0
Tps adjustment.. trust me. Mime dis the same thing. I adjusted it to spec and it still did it. I played with it a little .01 v at a time and found that .02 above the spec it always starts and idea down to 900 then after a few seconds isles down to 700.
#10
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Year: 1996
Model: Cherokee
Engine: 4.0
the IAC is the idle air control sensor, it is attached to your throttle body right by your tps. If your throttle body was really dirty, and you didn't pull the iac off when you cleaned everything, that could be your issue. It is very quick and easy to do, and can not hurt if you clean it and it is not the issue.
#11
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Year: 2000
Model: Grand Cherokee
Engine: 4.0
IAC
I cleaned the IAC as well, didnt know what it was but it was dirty. it helped the idle some but it is still a little high. I will check all the other things. thanks for the help
#12
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Year: 1990
Model: Cherokee
Engine: The venerable 4.0
Originally Posted by reebeno
I cleaned the IAC as well, didnt know what it was but it was dirty. it helped the idle some but it is still a little high. I will check all the other things. thanks for the help
#14
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Year: 1990
Model: Cherokee
Engine: The venerable 4.0
Originally Posted by 413maxwedge
They have code readers for pre obd2 they can read the obd1 code
#15
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Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
At this point, my money's on the TPS. PM me with your email address and I'll send you simple instructions to test/adjust the TPS on a Renix.