Looking for some info. I drive my 01 XJ daily to work and back (about 50 miles round trip), on the way home if I stop for 10 mins or so, when I start her back up, I get sputtering, rough idleing etc. Check engine light came on last time, Auto X-ray says "Misfire in Cylinder 3". What's the diagnosis??? 143,xxx miles, runs perfect on the way to work and back. Runs fine for longer trips. Just when i shut it off for a bit and restart after it's warmed up, it sputters and idles rough. Doesn't do it everytime either. Help?

 

it called heat soak or something, apparently the number 3 injector is too close to the exhaust manifold so when you do what you mentioned the fuel vaporizes causing the rough idle
anyway the fix is wrapping the injector in some sort of insulation like a spark plug wire heat shield

 

last tune up was? check compression. this will tell you good info. if it's good it is either a coil, plug, injector, ecu, if you have a compression issue it is mechanical... I check compression before spending any money on parts replacement. also since its a 01 and the head cracks between 3-4 cyl i would take off the oil cap and check for a green line, and compression before spending money on maybes.........

 

last tune up was last march when i bought it, 15k miles. will check compression. thanks.

 

90 percent sure it's your coil it'll start with one misfire then they all go down hill mine had 130k when it went bad it did the same thing only misfire on 4

 

not trying to scare you, 90% of miss fires I see at work are not compression. but checking is worth it when throwing parts at it aren't the problem. sounds like a coil to me. most fail under heat conditions more then cold... but its all a guess until elimination of the other options. i wish the coils where individual so you could move it and see if it moves with it... but thats not an option...

 

does the rough idle go away after you rev the motor for a little bit?

 

check the crank sensor....had the same problem

 

What you describe are the absolute classic symptoms of "heat soak". When it occurs, it can trip a code for a cylinder 3 misfire.

And the 00-01 XJs are the most susceptible to this malady. Here is more, but know that the fix recommended by Jeep of wrapping the injector is pretty feeble and doesn't work for most. If you are bothered enough by it, options are installing hood louvers to lower engine bay temps, and also installing a timer on the e-fan so that it runs for a bit after you turn the ignition off, again....lowering engine bay temperatures. (the e-fan mod works quite well). SEARCH.

Here is the TSB from Jeep on this.


TSB
1803103 - 4.0L ROUGH ENGINE IDLE AFTER RESTART FOLLOWING A HOT SOAK
Date: 09/05/03 (supercedes 1802702 dated 09/06/02)
Model Year(s): 1999-2004

Description: NOTE: This bulletin applies to vehicles equipped with a 4.0L engine. This bulletin involves the installation of a fuel injector insulator sleeve.

Details: Customers may describe a 20 to 30 second rough idle following the restart of a heat soaked engine. This condition may be most noticeable when the engine is restarted following a prior 10 to 20 minute heat soak in hot ambient conditions of approximately 32 C (90ºF) or higher. This condition may be consistent with short city stop-and-go driving trips and can be aggravated by the use of fuel with a high ethanol content. Depending upon various conditions a MIL may occur due to DTC P0303 - Cylinder #3 Misfire.

This condition may be caused by heat from the exhaust manifold that following engine shut down migrates to the area around injector #3 and causes fuel vapor to form within the injector. This in turn may cause a momentary misfire of cylinder #3 until the fuel vapor is cleared of injector #3. The insulator sleeve lowers the injector #3 temperature to a point below which the fuel will not normally vaporize.

If vehicle exhibits a rough idle, and if a misfire of cylinder #3 is observed following a 10 to 20 minute hot soak, perform the Repair Procedure.

Parts required:
56028371AA Ignition Wire Shield

Repair procedure:
1. Cut insulator sleeve, p/n 56028371AA, to make two (2) insulator sleeves about 25-30 mm (1 in.) in length. See diagram.
2. Install one sleeve around injector #3, with the slit on the upward facing side of the injector. Install the other sleeve with the slit on the downward facing side of the injector.
3. Confirm sleeve is flush to intake manifold surface around injector.
4. Check injector #3 wire and ensure that the injector is rotated to a 2 o'clock position.

 

^ interesting. fits what your describing. I haven't ran across this tsb... good info

 

Thanks TJ, that sounds exactly like what is happening. It doesn't bother me too much, and doesn't happen too often. Thanks for everyone's advice.

 

I love this site! I'm having the same problem and being new to jeeps this is a life saver. I have heard about the over heating issue prior to reading this post too. Iwas afraid it was going to be something more serious

 

My truck has the exact same problem. Had it before the new engine, has it now with new engine. I have cut holes into the hood and installed vents. I also did this:

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I wrapped each injector and the whole fuel rail with skinny header wrap.

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It only happens during the run it hard, shut off, run it again after 15 minutes BS so I have yet to test my header wrap experiment fully. Work is 50 miles away so when I get here, I don't run the truck until I'm ready to go home. Probably do more start-stop errand running this weekend and will give it a good try. Have any links to this timer on the e-fan? That sounds promising.

Mine is a 2000 model. I have read this only happens to the 2000 and 2001 trucks? I believe the only difference is these trucks have the coil packs and no dizzy? Or did Jeep change the exhaust/intake manifolds? I wonder if an intake/exhaust setup from a '99 or older would fix the problem. I'd gladly give up a couple HP's for more reliability. If you look through my pics on Image Shack there, you'll see my low-buck hood vents too.

 

I'm thinking about this fan switch more, can I just run the stock e-fan to constant, fused, power so when the engine cools sufficiently, it will just shut off? I want it to run for a few minutes after I shut down the truck.

 

I'm having the exact same problem. I went ahead and changed my spark plugs and ignition coil. My Jeep has 164,000 miles on it, of which, I have driven the last 20K. It was my girlfriends' car before I had it and who knows when the spark plugs had been done. I am also curious about doing the e-fan.