dans01classic

Alright, I thought I had fixed this problem, but apparently not. A few months back my check engine light came on. I went out and bought a scanner and plugged it in. It read four codes. 1) randum misfire in cylinders. 2)Misfire in Cylinder 3. 4)Misfire in cylinder 6. and 4)bad fuel injector three.

So I checked the fuel injectors. One of the clips was broken so it wasn't getting a good connection. I got a new clip. So that problem was fixed.

I asked a mechanic about the other stuff and he said the plugs were probably bad. So I put some new plugs in it. After a few couple hundred miles the light came back on. Same 3 misfire codes. So then I purchased new coil packs and wires (or whatever they are called) and air filter and did a full tune up on the truck.

I cleared the code and it stayed off for like 600 miles or so, so I thought it was good. Wrong, the light came back on last night. Same codes. I'm stumped.

Anyone else had this problem? Any Ideas of what else it could be? I dont want to pay the jeep dealership hundreds of dollars just to diagnose the problem and then want a thousand more to fix it.

winston427

Does it ever have a stumbling issue when it has been driven, parked for about 10-15 minutes, and the restarted?

dans01classic

Not that i recall. When i am idling I can feel a bit of a miss. But its not much at all. It doesnt bother me, i just cant stand the check engine light.

winston427

Some of the later models have a heat soak TSB that suggests a heat shield to be installed at the dealer. The problem is when the Jeep is turned off the heat from the exhaust manifold migrates up into the fuel rail and boils the fuel causes the injector to vapor lock and sets off the CEL. This is most common on the #2 and #3 cylinders and reads a misfire and fuel injector trouble code.

dans01classic

I did not know that. Is there any way I can check this without taking it into the dealership?

winston427

The TSB covers all 4.0 Cherokees within a certain year range. I do not know which years exactly but it does include the 00 and 01 models. My brother has access to all the TSBs and recalls online and I will get him to pull it up tommorow and pm it to you. There has been a lot of talk about this problem on here and a couple of members have used the header heat wrap tape on their exhaust manifolds to combat to problem. Some have had success and other not so much.

dans01classic

Thanks a lot. I appritiate a bunch.

under construction

hello, I have an 01 as well have fixed the issue with the engine code on #3 cylinder, however know I have one with #4, have not done same fix yet, but have recently cleaned fuel rail and injector ports installed new injectors and coil pack, its so bad now that when the light is on it "flashes" indicating major misfire. I am compression testing tonight and was wanting feedback to see if I am missing something here.

winston427

A flashing CEL is your vehicles warning sign for impending catastrophic failure. Do not drive it when it is flashing. If it started flashing after a heat soak restart, then let it cool down completely, restart it and check the CEL code. It will most likely be another injector misfire code. The misfiring injector could sticking in the fully open position and dumping raw fuel into the exhaust. Excessive raw fuel running into the cat conv will trigger a flashing CEL and will rapidly melt the substrate inside the cat and clog it up. Leaving you with even more expensive repairs. Especially on the 00-01 models that have 4 cats on them.

under construction

well if the injector is indeed sticking then it has to be a electrical problem as ALL injectors have been replaced (had code before and after replacment)
compression tested last night #4 has 170lbs all others are 150-160lb area this is leading me to think I have a broken or lazy valve spring, am I on the right train of thought here?

jarretthise

Well do you hear any clatter coming from that area? Put your ear up to your valve cover and listen closely. If you have a lazy or broken valve spring your most likely going to hear clatter from it.