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Discussion Starter · #1 ·
This is my 2001 Cherokee, 4.0L with 206k miles. Every now and then I get a heat soak issue, where the Jeep starts but has no power. You can floor it, the speed remains near idle, then it slowly builds RPMs, then it’s fine. It’s so hard to recreate the issue. The stop has to be longer than stopping at the mail box, but less time than the dog park. I read an old TSB which said let it sit 10-20 minutes but I can’t consistently get this to happen.

So far, I’ve tackled the fuel side of the issue: new insulation between the manifold and fuel rail. For the heck of it I also threw in new Bosch 4 hole injectors. Boy is it smooth now - I’d recommend the 4 hole injectors to anyone with a 4.0L. I also changed the plugs, which looked good but had some eroded gaps. No two gaps were the same.

I guess the next suspect if it happens again is the crank sensor. Never set the CEL, but did have pending misfire codes, p0300, p0301, p0306.
 

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Which design is older? The Jeep Cherokee XJ or the Goodyear Wrangler Radial? I think they may have finally stopped making this tire. These are 3 years old. Tread design and sidewall look unchanged from the 1980s.
Automotive parking light Wheel Automotive side marker light Tire Land vehicle
 

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This is my 2001 Cherokee, 4.0L with 206k miles. Every now and then I get a heat soak issue, where the Jeep starts but has no power. You can floor it, the speed remains near idle, then it slowly builds RPMs, then it’s fine. It’s so hard to recreate the issue. The stop has to be longer than stopping at the mail box, but less time than the dog park. I read an old TSB which said let it sit 10-20 minutes but I can’t consistently get this to happen.

So far, I’ve tackled the fuel side of the issue: new insulation between the manifold and fuel rail. For the heck of it I also threw in new Bosch 4 hole injectors. Boy is it smooth now - I’d recommend the 4 hole injectors to anyone with a 4.0L. I also changed the plugs, which looked good but had some eroded gaps. No two gaps were the same.

I guess the next suspect if it happens again is the crank sensor. Never set the CEL, but did have pending misfire codes, p0300, p0301, p0306.
My son has a 2003 Jeep Wranger Rubicon with the 4.0 engine and 5-speed manual transmission.

Quite some time ago he had the same problem with heat soak (10-15 minutes after driving and parking in the summer heat) - with a misfire, hard to rev and a check-engine light with a misfire code.

There was a TSB that instructed the dealer (me......) to insulate several of the fuel injectors with a sleeve that had to be cut to fit. The part was available from Jeep and was very inexpensive. I did that for him, and he has not had a recurrence in many years.

I don’t have the TSB handy - but could try to find it if you think it would help.
 

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Discussion Starter · #4 ·
Thanks! That’s basically what I read. I didn’t get the Mopar parts, but did put a new insulation pad and injector wrap. The kit had fuel rail wrap but I didn’t install it.
 
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Thanks! That’s basically what I read. I didn’t get the Mopar parts, but did put a new insulation pad and injector wrap. The kit had fuel rail wrap but I didn’t install it.

I didn’t wrap the fuel rail - but the Mopar insulation wrap / tube on the fuel injector (I think it was two of them per the TSB) worked.

Did you buy an aftermarket kit with all the supplies?
 

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Discussion Starter · #6 ·
I didn’t wrap the fuel rail - but the Mopar insulation wrap / tube on the fuel injector (I think it was two of them per the TSB) worked.

Did you buy an aftermarket kit with all the supplies?
Yes, injector rail wrap, injector wraps, and a heat shield to place on top the manifold.
 
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Discussion Starter · #7 ·
I think I've successfully eliminated the heat soak issue.
Now to find the annoying whistle that comes and goes on coasting/deceleration (brake booster, intake manifold, throttle body are suggested causes).
 
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Discussion Starter · #9 ·
Do you think the aftermarket kit of wraps and a heat shield solved the problem?
I do. though I think I could have also installed a new Mopar shield and had good results too. The old heat shield that was there was deteriorated and missing large pieces.
This is what I used, though I did not wrap the fuel rail.
 
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I do. though I think I could have also installed a new Mopar shield and had good results too. The old heat shield that was there was deteriorated and missing large pieces.
This is what I used, though I did not wrap the fuel rail.

Thanks - I’ve bookmarked the parts.

My son’s 2003 Jeep Wranger Rubicon has only about 65,xxx miles on it and although it has a/c - he usually drives it in the hot weather with the top down and no a/c (and mostly on open roads and country roads). I don’t know if that helps prevent the heat soak or not?

When we change the oil + filter for the winter soon, I will check the factory heat shield to see if it is in good shape. He installs the factory hardtop for the winter, and uses the vehicle for a severe weather ride, as we live in the Midwest (and he has a company car he drives daily).

Thanks again.
 

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Discussion Starter · #11 ·
So, after thinking I had this resolved the issue popped back up again. But I’m not sure it’s the same cause. Before the problem was a lack of power occasionally after a hot restart.
It’s now a strong miss after a hot restart that goes away after a few seconds and I can duplicate the issue easier now. I may take a gamble on the crank sensor although the only code set this time was p0303 (cylinder 3 misfire).
or maybe I need to install the fuel rail wrap I didn’t use from the kit. Odd it’s happened more regularly in cooler weather now.
 

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Didn't the 2000-01 years have issues with cracked/warped heads?

It might not hurt to put a vacuum gauge to 'er, and see what it says. Maybe it's just the gasket being fussy.

Heck, it may just have an air pocket somewhere in the cooling system.
 

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Discussion Starter · #13 ·
Didn't the 2000-01 years have issues with cracked/warped heads?

It might not hurt to put a vacuum gauge to 'er, and see what it says. Maybe it's just the gasket being fussy.

Heck, it may just have an air pocket somewhere in the cooling system.
I’d have expected some indication on the old spark plugs if there was a mechanical issue with one cylinder. The problem goes away so predictably and quickly after a hot restart that it’s either got to be flaky electronics or the fuel is still evaporating in the line.
 

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There were a couple of TSBs on this. # 18-031-03 and # 18-039-03.
One an injector insulating sleeve and the other a PCM software update.

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