The code told you what the problem was, Cylinder 3 misfire. That does not mean that it cannot cure itself. I have had older engines carbon foul a plug when a little piece of build up gets loose. sometimes it is still stuck to the plug when you pull it and sometimes it breaks loose when you pop the plug loose. I would guess that you might just have had such an event. It could also be that the #3 plug is marginal at the moment and you might see this code again in a few thousand miles as the plug continues to wear.

 

This is a known problem with the 2000-2001 XJs that have the coil pack ignition. If you search "heat soak" or "rough idle after hot start" you will see many having the same issue. The problem is that the engine gets very hot when it bakes under the hood, which makes the fuel in the injector (typically the #3) pretty hot also. On a hot start the fuel in the cylinder won't ignite correctly and cause the misfire until new cooler fuel is brought into the cylinder. This is why the problem happens most often in hotter weather or after running the engine awhile, and the miss usually goes away after revving the engine.

The fix is fairly easy... My 2000 had this same problem last summer.

I had it fixed by the dealer because they told me it was a recall, although some tell me the recall was only on Wranglers. Either way, the problem hasn't come back yet. What the dealer did was put a heat shield around the #3 injector, to prevent the fuel from heating up and causing the missfire. I'll try to put up some pics of it.

Edit: In these pics, it is the tan shield surrounding the injector. Might be kind of hard to see.

 

Definitely best if you post the EXACT code numbers here. That second code (undefined) is a wildcard.

Without the exact codes, you may be barking up the wrong tree...

 

mine does that same thing too. cylinder 3 misfire. could you put the heat shield on by yourself?

 

Here:

Recall Reason FUEL SYSTEM, GASOLINE:FUEL INJECTION SYSTEM:INJECTORS
Recall Date APR 08, 2002
Model Affected CHEROKEE
Potential Units Affected 1115322

Recall Summary
ON CERTAIN SPORT UTILITY VEHICLES EQUIPPED WITH A 4.0L ENGINE ONLY, THE DESIGN OF THE INTAKE AND EXHAUST MANIFOLDS COULD ALLOW DEBRIS TO ACCUMULATE AT THE #3 CYLINDER LOCATION.

Consequence
THIS COULD RESULT IN A VEHICLE FIRE.

Remedy
DEALERS WILL INSTALL A MANIFOLD SHIELD TO MODIFY THE AIR FLOW CHARACTERISTICS AND TO PREVENT THE ACCUMULATION OF DEBRIS IN THE AREA OF THE #3 CYLINDER. OWNER NOTIFICATION BEGAN MAY 13, 2002. OWNERS WHO TAKE THEIR VEHICLES TO AN AUTHORIZED DEALER ON AN AGREED UPON SERVICE DATE AND DO NOT RECEIVE THE FREE REMEDY WITHIN A REASONABLE TIME SHOULD CONTACT DAIMLERCHRYSLER AT 1-800-853-1403.

Notes
DAIMLERCHRYSLER CORPORATION B06

This bulletin is supplied as technical information only and is not an authorization for repair. No part of this publication may be reproduced, stored in a retreival system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, or otherwise, without written permission of DaimlerChrysler Corporation.

THIS BULLETIN SUPERSEDES TECHNICAL SERVICE BULLETIN 18-027-02,
DATED SEPTEMBER 06, 2002, WHICH SHOULD BE REMOVED FROM
YOUR FILES. THIS IS A COMPLETE REVISION AND NO ASTERISKS
HAVE BEEN USED TO HIGHLIGHT REVISIONS.

SUBJECT:
4.0L Rough Engine Idle After Restart Following A Hot Soak

OVERVIEW:
This bulletin involves the installation of a fuel injector insulator sleeve.

MODELS:
2000-2004 (TJ) Wrangler (Domestic and International Markets)
1999-2004 (WJ) Grand Cherokee (Domestic and International Markets)
2001-2004 (WG) Grand Cherokee (International Market)
2000-2001 (XJ) Jeep Cherokee (Domestic and International Markets)
NOTE: This bulletin applies to vehicles equipped with a 4.0L engine (sales code = ERH)

SYMPTOM/CONDITION:
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.

DIAGNOSIS:
1. 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:
Qty. Part No. Description

1 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.
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 (from driver's side of vehicle).

POLICY:
Reimbursable within the provisions of the warranty.
TIME ALLOWANCE: 0.2hrs

FAILURE CODE:
AM Authorized Modification

10char

 

Here:

10char

It did exactly that. Think if brought it to the dealer they'd fix it free? How do I prove it's the recall? Same damn motor why not

 

-something relay failure

Doesn't mean squat. Post the specific codes.

 

Print off the TSB and see if they will do it
Here is the link

http://www.wjjeeps.com/tsb/tsb_wj_1803103.pdf

 

Win! Thanks!

 

did anyone have success with this at the dealer? other than jeepkid i mean... id like to go there like today to get it done before i have to go back to school...i dont want to go and waste my time

 

That poor excuse for a heat shield that the dealer will put on there is crap, I still had heat soak issues after they put it on. Here is what I did:

Found something the other day at work that should completely solve any more heat soak issues I'm having(beyond the big *** hood vent and soon Taurus fan swap). Heat Sheath - Aluminized Sleeving | Design Engineering, Inc. We only carry the 3/4" stuff (at O'Reilly), but I figured I would give it a shot and see how it works:

I'm using the intake of the other engine I have as a chance to test fit every thing, makes it nice so I don't have to fiddle with trying to figure out everything on my engine. 3/4" is a little too big, but it works. Just put the sleeve over the injector, pinch the excess material, fold it over, and secure it with a small zip tie, I put the doubled over part on the bottom side of the injector for a little better insulation from the manifold. The great thing about it is I think they sell you about 2' of sleeving, I only used 8-9" of it trying to figure out the best set up, and have cut that down to about 6" now, plenty to do a couple more engines.

 

I have a P0300 random Misfire. I reset the code and all was fine till I was driving it later tonight and the light came back on so i'm assuming its the same code. No what?

 

I move to Miami FL. My 2001 Jeep XJ was running bad when I restarted after a quick stop and these very long Red Lights. The Cylinder #3 Misfire is caused by the Fuel being Vaporized. This issue also caused after a quick stop on restarting to run ruff as can be. Also before I moved here I had the So-called Jeep Factory Fix for this issue Installed but down here it's worthless.

To stop this problem buy 2000 Degree Thermo-Shield from Cool It. And a lot of Small auto Cable Ties. Wrap every Injector, Fuel Rail and wrap the Gas Line all the way back to Fire Wall securing the Thermo-Shield in place with the Cable Ties....!!!! Problem goes away forever.

 

Check oil for coolant and coolant for oil.

 

I have replaced the coil pack, all the spark plugs, and cleaned out the injectors on my 2001 cherokee and I'm still getting a cylinder 3 misfire code. It only runs rough when I start it up, and it's completely random when it happens. I'm out of ideas of what the solution could be. Has anyone had the same problem? Please help.

 

misfire cylinder 3 recurring problem

I have a 2001 Jeep Cherokee Sport. The heat shield recall was addressed early on and never had any problems until about 3 years ago. Now I get a check engine light, sometimes it flashes then steadies. Every time... the code is misfire on cylinder 3, or occasionally random misfire and misfire on cylinder 3. I exhausted the patience of one mechanic shop who refused to proceed further without just replacing the entire engine for $5000+. New mechanic is very patient but we still can't find what is causing this. He has even searched a paid mechanic online data base.

We have done just about everything one can think of short of replacing computers in the thing. He is now of the mind that it is a glitchy electrical issue or a heat soak issue. Like I said, the heat shield issue has already been addressed. The rough idle happens mostly after I have been running errands and have stopped and started the Jeep a few times in town. The check engine light will flash, then steady and as I get out and can run it evenly it smooths out and runs fine. The check engine light will also come on randomly down the road, flash, steady and the vehicle doesn't hesitate in the least, running smooth the whole time. Also...it will go off randomly, as if it resets itself. It's entirely infuriating as the Jeep continues to run fine for a 14 year old vehicle. Regular maintenance and oil changes are done routinely.

 

Have you checked the compression? Fuel pressure? Swapped injectors?

Here's something I wrote a while ago. Perhaps it'll give you some ideas on things to look for: Misfire Diagnosis Guide

 

I had a misfire on 3,4,5 or 3,4,6.New plugs and a new coil pack and she was purring like a kitten. 2000 jeep cherokee.

 

That was happening to me. I first replaced all 6 spark plugs and the coil. It didn't fix the problem. I learned that the 3rd cylinder's injector gets hotter than the others because it's the closest to the exhaust manifold. It's apparently common for the 3rd one to overheat and crack. This happened to my 2001 XJ. The other injectors were fine. He replaced it, and installed a heat shield.