I have a 2001 Cherokee Sport with the 4.0 L. The vehicle belonged to a family member and was running rough after it was driven for 10-15 minutes. I checked it with an OBD2 unit and it threw a couple codes, including the P0303 misfire on #3 Cylinder. The other codes were related to large vacuum leaks associated to the vapor recovery system. I replaced a few parts there and solved that problem.
I read up on the heat soak issue and purchased the kit to install. Heat shield, wraps for all the injectors and a wrap for the fuel rail. Reset the computer and drove fine. Stopped for a bit and took off and within a couple miles it begins to shudder, CEL comes on and I nurse the vehicle home. Every time I try to accelerate, the problem persists. Check the codes and it's thrown the P0303 code again. I have replaced the injector and the spark plugs. I checked the compression on #3 and its 125. The head was replaced a couple years ago. I cleaned the throttle body and the TPS. The STFT and LTFT on banks 1 and 2 are within specs as well. The computer shows that the MAP sensor was 10in Hg when the code was thrown. The vehicle speed was 30 mph.
The jeep idles fine when it is first started. If you drive around town and don't have to accelerate quickly, it won't shudder, but it will still give you a blinking CEL. the moment you begin to accelerate, like getting on the freeway, it starts to hesitate and shudder.
Any suggestions?

 

I am not able to help with the actual issue but I do know that a solid CEL means there is an issue that will need attention. A blinking CEL relates to a serious issue that needs to be immediately addressed and vehicle should not be driven.

 

There should be some troubleshooting that can be performed to the coil pack. I believe it is resistance checks. So you will need a multimeter. Let me looks for the chart, BRB.

 

See here====> https://www.cherokeeforum.com/f2/tes...l-rail-204328/

 

I'm off work tomorrow and I will give that a shot. thanks

 

Checked the coil rail and it's within spec. Discovered the intake manifold bolts were not tight to spec. They were probably causing a intake leak when the engine heated up. Threw a P0203 code. Traced it to the damn clock spring. Disconnected it and that code went away. Jeep running much better but still throws a P0303 code yet the engine hasn't been hesitating on acceleration. I clear the code but it returns.

Suggestions?