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brianv
September 3rd, 2010, 08:01
Last week I drove 11 hours to school from NJ to Michigan in my 01 xj. Jeep ran fine the entire way there. I parked outside my dorm, proceeded to unpack it entirely, and then went to move it. Here's where I ran into my problem. It started, but sounded like it was running on two or three cylinders, and was really rough. I turned it off and tried to start it again and the same thing happened. I wasn't happy, but was at least glad it happened after my trip, and not during. I left the jeep there and went to dinner. After dinner, I went to start it again and it started up just fine, and has since.

I only bought the jeep a month ago and am not sure what could be the problem. My only thought was a problem that the previous owner said he had around 67k miles. He didn't know much about cars but this is what he wrote down that the mechanic said was wrong with jeep - "Oil was leaking onto spark plug causing failure in the back of gasket area. He put glue to stop leak. This caused cylinders 3&4 to go bad. I need a hard cover gasket before 10,000 miles or it might happen again". This was roughly 5k miles ago, and thought it would be fine until I had the time to look at it. Any help with any thoughts on what could have possibly happened would be great. Thanks.

lazyxj
September 3rd, 2010, 08:58
Sounds like a hot soak problem.
Try searching 'hot soak '
http://www.naxja.org/forum/search.php?searchid=4069508

anthrax323
September 3rd, 2010, 09:03
The issue you've described is likely the "heat soak" issue, in which engine and exhaust manifold heat cause injector #3 to go into vapor lock. Next time it happens, let the car run for about 30 seconds and see if it smooths back out. If it does, you've got vapor lock. There was a TSB issued for this problem, which is "resolved" by installing an insulation sleeve on injector #3... Quite the half-assed solution that didn't resolve my problem.

In any case, my 2001 experiences the same problem under these conditions:

1) It's hot outside.
2) The engine has gotten quite hot (either due to a long trip or running the AC).
3) The car is started after sitting for a few minutes (5 to 20 minutes).

If the above conditions are what resulted in this behavior from your car, then it's almost certainly this problem. Some suggested workarounds are:

- Wrap your exhaust headers with additional insulation to reduce the amount of heat emitted.
- Install a fan timer to allow the electric aux fan to run for a minute or two after powering the car off.

For some reason, my check engine light resets itself now whenever this issue is encountered (I think it's error code P0301 or P0303, don't remember) so I just deal with it. If the car is hot and gets a rough idle upon restart, just let it idle itself out for 30 seconds or so and you should be fine. Whatever you do, do not attempt to load the engine during this time (rev it, put it in gear, etc) as that will almost certainly ensure you'll throw a code.

Ian Christiansen
September 3rd, 2010, 09:06
My 2001 had the same problem. I installed a set of Gen-Right hood vents and it hasn't happened since.

lazyxj
September 3rd, 2010, 10:29
- Wrap your exhaust headers with additional insulation to reduce the amount of heat emitted.
- Install a fan timer to allow the electric aux fan to run for a minute or two after powering the car off.

Beware that wrapping headers can lead to early rust out, especially in wet climates.

The timer method is what I have used during the last two summers with good success.
http://www.flickr.com/photos/lwade/sets/72157617434915718/

Also a leaky injector or a fuel pump that does not hold its pressure, when the engine is off, can contribute to the problem. Pressure in the fuel line helps prevent the formation of bubbles.

anthrax323
September 3rd, 2010, 11:13
Good point. I need to go the fan timer route one of these days.

Quick thought on the headers... Does anyone think that eliminating the pre-cats with aftermarket/performance headers would help mitigate the issue? Methinks that the pre-cats are responsible for a good amount of the lingering heat (large mass, lots of heat)... Am I wrong on this?

joe_peters
September 3rd, 2010, 11:19
If it is heat soak, which it definitely sounds like, it results in a cylinder number 3 misfire P0303. The factory TSB "fix" is an insulating sleeve for the number 3 injector, the dealer charges about $8 for the part. Some have had luck with that as a fix.

If you have the 50-state emissions package--two mini-CATs in the exhaust manifold--wrapping is NOT an option.

The electric timer has proven successful for a number of people. Sample timer: http://www.at-fairfax.com/P1786-ELK-960.htm Running the aux fan on the timer for about 5 minutes after shutdown usually prevents the problem.

joe_peters
September 3rd, 2010, 11:22
Good point. I need to go the fan timer route one of these days.

Quick thought on the headers... Does anyone think that eliminating the pre-cats with aftermarket/performance headers would help mitigate the issue? Methinks that the pre-cats are responsible for a good amount of the lingering heat (large mass, lots of heat)... Am I wrong on this?

It would seem logical, but I doubt it would, and it wouldn't likely be legal at a federal or state level.

The reason I don't think it would help is the problem is covered for 99-04 4.0s, regardless of the emissions package of the vehicle--in other words, the problem is there on the 4.0s without the mini-CATs that are only 49-state emissions certified.

brianv
September 7th, 2010, 18:25
hey guys, thanks for all the help. my guess is that it was heat soak. my only concern was that i stopped 3-4 times on the trip to get gas, one of which was just five minutes before the rough idle happened.

birchlakeXJ
September 8th, 2010, 08:34
Heat soak can be kind of random......

Have you ever seen a check engine light? Even so, with it running that rough, you probably have a stored code in the computer. If I were you, I would get a code reader or a scantool and see if there are any stored codes. Autozone will do this for you for free.

This information can be helpful here......post the EXACT code number(s) here for comment if you are so inclined.

As for what the previous owner wrote down, it is kind of cryptic but I am assuming that your engine has a valve cover gasket leak, resulting in oil migrating down. Look closely around your valve cover and you should be able to see if it is leaking from there or not. It is a small repair.

Enjoy your 2001 and be sure it does NOT overheat as the 01 came from the factory with the infamous 0331 head which is susceptible to cracking between cylinders 3-4, especially when the engine is overheated (keep up with ALL cooling system maintenance!).

EMSJEEP
September 8th, 2010, 12:12
FWIW I get a cylinder 1 code...2001 same issues...mine happens while driving sometimes...also resulting in an 02 sensor code, has done this for years, in the summer only...

joe_peters
September 8th, 2010, 14:40
FWIW I get a cylinder 1 code...2001 same issues...mine happens while driving sometimes...also resulting in an 02 sensor code, has done this for years, in the summer only...

Willing to try something? Try swapping your coil packs, see if the issue follows the pack. Some reports of "heat" or "stress" cracks allowing them to fire to ground under the right circumstances.

EMSJEEP
September 8th, 2010, 16:00
Willing to try something? Try swapping your coil packs, see if the issue follows the pack. Some reports of "heat" or "stress" cracks allowing them to fire to ground under the right circumstances.

Hmm...I need to do plugs anyway. I think the dielectric grease was a bad idea.

joe_peters
September 8th, 2010, 16:06
Hmm...I need to do plugs anyway. I think the dielectric grease was a bad idea.

Worth a shot.

Are you running/going to run the NGK V-Fire plugs--Chryco recommended them for the distributorless ignitions.

EMSJEEP
September 8th, 2010, 16:20
Worth a shot.

Are you running/going to run the NGK V-Fire plugs--Chryco recommended them for the distributorless ignitions.

I run the stock plugs from the dealer:firedevil, they actually seem to work the best (instead of off brands)...the only replacement part I will buy from them...

DenLip
September 8th, 2010, 16:35
hey guys, thanks for all the help. my guess is that it was heat soak. my only concern was that i stopped 3-4 times on the trip to get gas, one of which was just five minutes before the rough idle happened.

My '00 has done the heat-soak thing to me a number of times... always in the same situations: long highway drive (hours), stop for fuel/pee/etc... come back out after sitting for maybe 10-20 minutes... and she misses on me. The first time was when it was only a year or two old... and just before the heat-shield recall was put on. Didn't help. It doesn't happen to me enough to worry too much. My XJ rarely sees long highway trips. Why would I, when my car gets 28 mpg? ;)