GoingForBroke

I'm seriously 8 hours from beginning a pretty long vacation with the jeep and the damn thing just starting flashing the check engine light at me.

2001 Cherokee Classic, 4.0, 146k miles
P0300 - Multiple Cylinder Misfire
P0303 - Cylinder 3 misfire
PENDING CODE P0304 - Cylinder 4 misfire
Roughish idle after starting up
CEL light blinking when accelerating says the wife (unconfirmed)
(When I drove it, the light was on the whole time)

Most recent work done:
This week:
Installed intake manifold debris cover
Installed a new coolant temperature sensor
600 miles ago:
New oil pan gasket and rear main seal
2000 miles ago:
Replaced the cylinder head with a new Clearwater Head
New gaskets all around
Upgraded battery cables
Oil change, coolant flush, coolant and heater hoses, water pump


What the hell should I do to trouble shoot....

HudsonN

Sounds to me like heatsoak.

The 2000 and 2001 XJs are notorious for it.

The fuel in the fuel rail vaporizes (right around the 3rd and 4th) cylinder and if you don't let the jeep cool off after you park it and go to restart it within like 20 minutes of shutting it off it'lll idle real rough and spit and sputter until the fuel in the rail becomes un-vaporized.

Cheddarnut

I believe there was originally a recall to add insulation around injector 3 to prevent heat soak and install the debris shield which was supposed to prevent leaves and trash building up around the same injector. Try adding insulation around the injector and see if the problems resolve.

GoingForBroke

I actually just replaced this part, because It was lost during the head replacement. Honestly the issue has become a problem since I install the debris shield. I had experienced the heat soak issue previously on a long road trip, and ordered the shield from a dealership to help prevent it. I had not gotten a code thrown until today, two days after putting the part on.

Cheddarnut

I think the shield really is more for debris than heat, it's not shaped or placed in a way that would really block any heat. I would still insulate the injector and see if it gets better.

cliffpenick

Could be a coil pack also. Especially if it is on acceleration. Normally heatsoak goes away pretty quickly.