z.rose188

I have a 2000 4.0L Jeep Cherokee Classic. Usually when it gets hot and i turn the motor off, shortly after when i restart it. It seems to misfire. It doesnt shoot off a code but about a couple minute laters the fuel vapors in the injector will evap out and runs normal again. How do i fix this problem?

djb383

How long has it been since a tune-up/maintenance? I would think heat soak would be a non-issue this time of year (cool/cold ambient temps).

freestylr2525

i was getting that over summer. I replaced my spark plugs and wrapped my fuel rail with the injectors in reflective heat tape. Haven't had a problem since.

cf1k1

THIS

z.rose188

I've just recently changed the plugs and since then it does it way more often now. It used to only do it if I was out climbing hills or riding on the beach. But now its just driving around town. The engine is well maintained

djb383

I'd just almost bet it's something other than fuel injector heat soak....it's just too cool now. Seems coincidental that it does more often after a recent plug change......u positive COP/elec connections are good?

cf1k1

With the 97+ it's a real common issue. Run the rig. Let it sit for 10 or so minutes. BAM! Heatsoak misfire, cel etc

djb383

Ours is a '98, been thru 2 triple digit heat summers, starts instantly, runs smooth as silk.

chill

leaking injector. when you turn off the jeep the fuel rail is still under pressure so a week injector could be leaking some into the cylinder.

gary s

My '01 did it for the 1st time this March towing my boat in Florida.Didn't know what it was at first,got the missfire code so I changed plugs on the road.Was fine until I got back to Illinois and it did it again,it was in the '40s outside.I put the insulator on the injector per the tsb. I also decided to pull out that stamped aluminum leaf guard that was put in on a recall.It seemed to shroud the injector keeping in the heat. Towed in the heat of July and had no trouble since.

tjwalker

1. Try the technical service bulletin fix by Jeep. Works for some, not so well for stubborn cases. More below. Get the parts kit from a Jeep dealer.

2. Install an e-fan timer which allows the e-fan to continue to run for a programmed amount of time when you turn the key to the off position. Reduces engine bay temps.

3. Cut in louvers into the hood

4. I've seen some guys perform all three of the above fixes to get relief. NAXJA Forum has quite an extensive thread library on heat soak.
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TSB1803103 - 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.