High idle after driving

jeepboy381

NAXJA Forum User

Location

Gresham, Or

• Dec 10, 2003

• #1

I have a 1987 Cherokee with the 4.0L in it, when I start it it idles completely fine at about 750RPM smoothly. After I have driven the Jeep at all it will continuously idle at about 1,300 RPM until I shut it down and let it sit for a while what could it be? I checked the TPS the Idle Stepper Motor, the MAP sensor, and I can't find any vacume leaks. :sunshine:

 

X

XJRob

NAXJA Forum User

Location

Arkansas

• Dec 10, 2003

• #2

next time you drive it and it acts this way, pull over and start unplugging sensors (starting with the Idle stepper motor, TPS, IAT, CamPS, etc.) one at a time until you notice a difference. This is what I normally do and usually pinpoint as being the idle stepper motor needing cleaning. There are some sensors that will kill the engine as soon as you unplug like the MAP and CPS.
I have ran through all of this with my 87.

 

sidriptide

nobody of any consequence

Location

western massachusetts

• Dec 11, 2003

• #3

i have the same problem on my 87 and although i have yet to troubleshoot it i attribute it to the TPS most likely.. it started after a good soaking with the hose and a few cans of de-greaser.. when you figure it out let us know because it's a common problem with a few guys here..
mike

 

M

MACH90XJ

NAXJA Forum User

Location

Oregon

• Dec 11, 2003

• #4

You should also check the linkage itself below where it runs down throttle body.XJROB has a good idea,when it happens start doing the wiggle and unplug test first,wiggle that throttle linkage when its acting up.I had a bent clip of some sort that would hangup everything from retuning to idle and it would not happen all the time.A little carb cleaner on those cables and linkage wont hurt with a touch of fresh lube on the exposed cable afterwards.

 

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DeathByXJ

NAXJA Forum User

Location

No. Hollywood, CA

• Dec 11, 2003

• #5

I second the suggestion to check your idle stepper motor.
My high idle issues went away after a good cleaning. Also blasted carburetor cleaner into the throttle body and it worked just fine. Seem to remember someone here saying to avoid some solvents-- you might do a search.

 

8

89xj

NAXJA Forum User

Location

aston,pa

• Dec 11, 2003

• #6

my 89 does the same thing. probably the idle stepper motor sticking. if your looking for vacuum leaks, might want to tighten your intake/exhaust manifold bolts.

 

sidriptide

nobody of any consequence

Location

western massachusetts

• Dec 11, 2003

• #7

you can get spray cans of throttle body cleaner.. it's safer for the sensors and such in an EFI system.... i have heard many people say carb cleaner is fine but it's worth the extra $1 to not take a chance on hurting the sensors.....
mike

 

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FatXJ

NAXJA Forum User

Location

South Range, MI

• Dec 13, 2003

• #8

I would check your intake manifold bolts and TB bolts. Often the high idle when warm indiactes the opening of an leak to allow for more air to enter the system which creates a high idle. Your gaskets might be leaking or your bolts may just be loose.

This is common for many vehicles.