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#1 06-05-2015 07:20:41

Winner
Newbie
Registered: 05-14-2009
Posts: 7

Engine idles high and clicking rocker

1987 Jeep Cherokee 4.0 4X4 Auto

First my very first rocker is clicking. I added some Seafoam and it has stopped but was curious if I need to replace something since I can't just tighten it like a GM engine.

Secondly, my engine cranks and idles really high 2500 - 3000 and I shut it off wiggle the TPS and MAP connectors and it cranks and runs fine. I'm guessing that the plugs are wearing out but I can't find a place to purchase either the plugs or the wiring harness. I just assume replace the whole harness. Anyone have one for sale or know where to get it.

I'm thinking I'll have to visit the junk yard for it...

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06-05-2015 07:20:41

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Re: Engine idles high and clicking rocker

#2 06-05-2015 07:21:24

peter
Helper
Registered: 10-05-2008
Posts: 16

Re: Engine idles high and clicking rocker

87 had a issue with high idle. Cleaning the air bleed in the throttle body would provide relief for awhile. There is also a resistor fix but I had that on my 87 and it didn't fix the problem. (I don't have the details on it either.)

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#3 06-05-2015 07:22:39

STAGGXJ
Helper
Registered: 03-15-2009
Posts: 27

Re: Engine idles high and clicking rocker

Mines an 88 and it seems to be working OK for now.  All I did was remove the IAC and cleaned all the carbon off with carburetor cleaner.

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#4 06-05-2015 07:23:45

evad
Enthusiast
Registered: 10-05-2008
Posts: 240

Re: Engine idles high and clicking rocker

have you watched the ohm drop on the TPS once its started ?? your TPS may be failing, of the temp sensor is failing causing a cold start condition.. both were my issue... Justin had me void out the temp sensor on mine since it was not hooked up.. ( no emissions on mine since it's OHV only)


Check out my Jeep XJ

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06-05-2015 07:23:45

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Re: Engine idles high and clicking rocker

#5 06-05-2015 07:25:40

nomis
Lurker
Registered: 04-21-2009
Posts: 4

Re: Engine idles high and clicking rocker

I'm not sure you can do anything about the clicking mechanically, but you can try running a heavier weight oil or adding Lucas. You'll notice the front of the 4.0 is slightly higher than the rear, allowing the possibility of starving the #1 area of oil (especially with a transfer case drop).
My old 4.0 had the clicking and started to get piston slap in the #1 on cold start ups before I put the new one in.
I would keep an ear out and do something if the clicking returns.

The owner's manual recommends:
20w40 or 20w50 for jeeps operating at 30 degrees F or higher
10w30 or 10w40 for jeeps operating at 0 degrees F and higher
5w30 for jeeps operating at 60 degrees F or lower(There is a viscosity chart that may make more sense if you see it, but alas I have no scanner at the moment).

Consequently the owner's manual (yes I still have it) also recommends servicing jeeps twice as frequently (6 months instead of 12 - 2500 miles instead of 5000, etc) if used under what they call "Heavy Duty Operation":

* Frequent starting and stopping
* Frequent long periods of engine idling
* Frequent short trips of less than 15 miles (24 km)
* Desert Operation
* Cold climate operation
* Sustained high speed operation
* Trailer towing
* Commercial service
* Frequent operation on dusty roads
* Off-road drivingI know I qualify for like 6 of those. I'm running 15w50 synthetic in my 4.0.

As far as the random high idle goes, I have the issue too. Mine happens to be the Idle Air Control (IAC) motor sticking open. Cleaning that port on the throttle body, as Leonard suggested, may help.
I haven't had the desire or time to hunt down the exact issue, but if I do I will let you know how it turns out.
I'm pretty sure it's mechanical as my idle immediately corrects itself if I tap on the side of the throttle body facing the valve cover (next to where the IAC passage and valve/motor are).
Also turning the ignition off then to on and waiting a bit before starting sometimes helps after the high idle start occurs.
Hope this helps.

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