Originally Posted by XJ Stryker

I hate to tell you this but if you run a search on NAXJA.org. There are alot of technical writes up there. This site is great but not as much info YET.

Originally Posted by FrankZ

1803103 - 4.0L ROUGH ENGINE IDLE AFTER RESTART FOLLOWING A HOT SOAK
Date: 09/05/03 (supersedes 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 (from driver’s side of vehicle

Originally Posted by muddeprived

This is a hit or miss fix, mostly a miss. Of all the p0303 misfire threads i've read about, 90% of them already had this heat shield installed by the PO or themselves and it did not cure the issue. Mine already had the heat shield on it when i bought it and it still misfires.

Originally Posted by beach dude

were you able to fix it? what was it if you did? ive got the same problem and i do already have the heat sheild installed.

Originally Posted by Handycapt

I had the same symptoms on my '98 XJ. For me it was cylinder 6. Never checked the codes, just had a misfire, rough idle, and a loss of power, usually would clean up after a while of running. Turned out that mine was just a dirty fuel rail. The end of the rail collects a lot of junk, and if you have been running with low gas on dirt roads a lot, then the vent hoses in the tank start to suck in dirty air. Since there is no in-line fuel filter a whole lot of dirt goes through the screen on the pump, and then into the system. Fuel system cleaner didn't work for me, I had to manually clean out the fuel rail (Carb cleaner is great), and replace the injector. (tried replacing the injector first... no dice).

The symptoms sound the same, have you been running on low gas on dirt roads?

Originally Posted by greencherokee

i had the same issue i did the whole injector shield thing and the rapped my exhaust in heat shield

Originally Posted by greencherokee

yup before i would let it sit for 5- 15 minutes and the motor heats up after running period and when id start it back up it would run like it was miss fireing but i would just hit the throttle a couple of times and it would go away but now i can turn it off and on all day and it fires right up with no missfire ooo and puting the exhaust rap on the headers is a painso i would recommend taking off the intakemanifold and exhaust manifold they both use the same gasket

Originally Posted by Blackcherokee290

yeah this problem is wat prompted me to learn to fix my own damn car.(2000 cherokee 4.0L I6) I bought a code scanner, came out with the P0303 code. My issue was I idled for awhile, shut it off for only a short time, then i restarted it and it shuttered and misfired. As I was getting ready to wrap the injector I discovered a different approach. I just rev the engine a bit before I shut it off. Never had a problem since. *Note* I only rev it when I think it might misfire when I turn it back on. (like getting out after eating a burger in a parking lot while idling to do a pitstop) It might sound odd but its been quite awhile since it has happened.