Hey guys. Your forum has been helping me so far in my quest to fix my jeep but I'm running into a brick wall here. I have a 2000 cherokee sport 4.0 with 161k mileage. I'm going to assume it is an XJ since it's nothing but problems. Now mind you, as much as I hate these problems, I love my jeep.
Due to antifreeze and overheating issues since I've had her, which blew my radiator apart last spring, I opted to not install a thermo this past summer and it did pretty well. Water pump was replaced and thermo changed to a 190 last fall. Still antifreeze went missing and the amount I needed to replace kept growing. Last week, after the head gasket blew, she had a full top end with a heavier head casting (old one was full of grease, forget oil, and was lighter so here again I have to assume it was the 0331). This fixed my missing antifreeze problem. We also did 2 oil changes, plugs, #2 rod (banana).
She ran like a queen for 4 days and sounded like a jeep should. I didn't push her so she could break in so to speak. Then, I noticed a slight hesitation, which in all honestly I know I've experienced before but now that she is quieter it's obvious. By the time I got to my friends house she was bucking more or less and the engine light came on. Blinking then steady. I counted 20 CEL blinks before each pause. Computer Code was p0303 (which I've gotten in the past as well)
We then changed the coil and #3 plug. Same. Every time she would warm up. Although, I did pick up on a slightly not so right startup. It felt a little less calm but not noticeable to those who don't drive her.
Then it seemed my injectors sprung a leak so we changed them out. #3 and #6 were cracked. #2 was leaking due to o-rings. We even changed #3 plug again. We threw the heat coil aside seeing I have never had a leaf in my manifold and opted to individually wrap each injector as one of your forum threads showed.
Now, I'm a sensitive person and an observer so I pick on on small things and notice off the wall stuff. During a test drive, as she shifted downhill and my ears popped, her tone and handling got better and she seemed to start getting shakier as she switched going uphill in the same dang spot on the hill. We took her through the same spot and each time she did the same thing giving me the p0303 but this time I get 17 blinks on the CEL. For ****s and giggles I tried the 'on off while holding the trip down' thing which only checks gauges and lights (I know I have the oil gauge sensor issue too but it's not a full time thing) and upon restarting her, she sounded better and no blinking but cel is still on. There is a little black unit under the hood on passengers side next to the ac in the back that clicks non stop when she starts acting up.
I'm at a complete loss and I'm completely broke after this. I'm looking at the TPS, map, etc etc etc etc etc etc. I'm thinking it's something that has not been changed causing all these issues as well as the possibility of something breaking during the top end, but she was perfect for 4 days which confuses the heck out of us. HELP!
Note... When I first got this vehicle in 2009 it was obvious it had been overheated. Stained with anti freeze on the underside of hood. A shop took the engine out, cleaned it, replaced freeze plugs, replaced water pump, hoses, radiator etc etc.