zshawkey

hello i have a 2000 jeep cherokee with a misfire in cyl 2 and 3 when i got the jeep i was told it needed a coil pack so i replaced the coil pack and spark plugs and still have the misfire in the same 2 and 3 cyl . i have checked the fuel injectors there functioning correctly im lost what do i do? it dont burn coolant or oil i have a check engine light i have code po300 po302 po303 heres a video

tjwalker

As you have the P0300 (random misfire), the problem is often a "shared" issue, a common issue that that can affect multiple or different
cylinders.

The first thing I always verify is fuel pressure. Must be done with a fuel pressure gauge. Gauge can be rented from many parts stores; call around. Easy to verify pressure. The spec. for the 2000 XJ is 49 psi, plus or minus 2 psi.

There certainly are a number of other things that could be causing this, but the fuel pressure is the first thing to rule in or out. I'll guarantee you it's job #1 if you took it into a shop.

Good luck and keep us updated!

Dumajones

What brand/kind of spark plugs did you use.. My 2000 only likes NGK ZFR5N.

zshawkey

i run ngk plugs .. well today i took the jeep out for a ride and it was running great then i shut it off to in my buddies house i came out and started it and it did somthing it has never done before the check engine was flashing and it seemed like it was missing on at least 4 cylinders it didant even want to move then i took it around the block and the check engine went off and it ran normal again? im super confused

Dumajones

Do you have California emissions, two mini cats under the intake. Ever hear of Heatsoak? kinda sounds like that. The 00-01 Jeep Cherokees with Cali emissions have a problem with heat soak on fuel injector 3 due to a lot of heat coming off the cats while sitting heating up the injector/injectors ..

I did this fix when mine was doing it. But I only have Fed not Cali emissions so hmm. It stopped after I wrapped each injector with heat shield wrap.


Here is the TBS report


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.


TSB for the cold start rough idle and P0303 code: TSB 18-010-01



Pic of my injectors

zshawkey

ill give that a try but even cold it still seems to miss.. i ordered a crankshaft position sensor just in case as well i hope its not the valves but i dont think it is since it dont burn oil coolent smoke and it dont suck air in the exhaust