Engine does't want to rev down....whats up?

xjsaretheway

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Sep 18, 2007
Location
Wilmington/Chapel HIll
97 cherokee 4.0, blip the throttle, hessitates then goes up to 2500, drops down to 2000 and just hangs there, and then slowly comes back down. When in gear, after touching the gas it just doesn't want to come back down all the way. If i put it in 1'st so it can't shift up, go up to 3000 and let off it doesn't slow down right away. This was really annoying while in 4Low bc tough the throttle and it wants to go.
Any ideas as to what is causing this? I just put in a new upstream O2 sensor and it's still doing it.
 
first is you Throtle body fully closed when running this high RPM's?

you could have a major vacumm leak try spray som carb cleanner aroung the intake gasket and vacuum lines . if th RPMS drop then tha is where your leak is

also Check you TPS sensor but I do not think that is it.
 
so the throttle body looks a lil dirty and i'm gonna clean the IAC.
Can i just spray carb and choke cleaner on it to clean? should I worry if this stuff makes it past the butterfly and down the Throttle body?
 
Dont spray the carb cleaner around the intake gaskets and stuff, it will swell them up and make it seem like you fixed the problem. As far as finding vacuum leaks, either use propane and listen for engine idle changes, or come let me hook up my smoke machine to it and we'll find all the leaks in about .2 seconds.

To clean the throttle body just start the engine and move the throttle plate back and forth by hand while spraying the cleaner all around inside the throttle body.

Don't just replace the TPS either, TEST IT! People around here love to spend money throwing parts at stuff until its fixed. You can easily test a TPS with a Digital multi meter
 
rbo1577186 said:
By chance, have you got the underside really wet recently?
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Are you seriously asking him this question? We have all found out that he has an obsession with water and mud. He should probably just get a boat but for some reason he seems to think that a XJ will float.
 
marvilusone said:
Are you seriously asking him this question? We have all found out that he has an obsession with water and mud. He should probably just get a boat but for some reason he seems to think that a XJ will float.
Click to expand...

this one has seen NO mud, NO water since i bought it. I do not wheel something without a snorkel. once again, NO WATER OR MUD. i've only driven it on the street and some sand. I sold my other xj that i did all that deep water stuff with.

Back to topic:

I removed the throttle body, cleaned it, replaced the IAC, now it idles alright, but a slight touch of the throttle and it jumps up to 2500-3000, and then slowly comes back down. what could be causing this?
 
I was asking because... once I took my jeep to the car wash to wash the salt off. Sprayed underneath thoroughly. When I fired it up, it idled high for a day and a half or so (2k +). It also idled down slowly. After it dried out it was fine. Have no idea what I done.
 
xjsaretheway said:
just remembered.....it has an aftermarket cam in it if that makes a differnece
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is it loading up and running rich?

and as for the mud/water.... that jeep has probably most definatly been COVERED in mud many many many times before you bought it
 
I would try what 90xj and sha ba do say. If those don't work, bring it by and I'll take a look at it and see what we can figure out.
Chad<---Eriks neighbor if there's any question there
 
thinks you should just set it on fire

-Erik <---- had to start closing his bedroom curtains b/c of a certain peeping-chad neighbot
 
one other thing a bad coolant temp sensor can make the engine think it is at a cold start and cause the idle to be high but in more cases than 1 the tps is the problem!!!
 
Don't kid yourself Erik, no one wants to see your scrawny ass. Erik's actually the reason that people in this neighborhhood have to lock their doors. No one wants a loud drunk walking in yelling, it gets old.
 
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