I have a 1997 Jeep Cherokee 4.0 6 cyl and I am at a wall with it. I cannot figure out what the problem is. I have had a few people look at it and I have been changing sensors upon sensors and I cannot figure out the problem!!
A few weeks ago it was overheating. I fixed that problem and now it is idling REALLY rough but sounds almost like a damn lawnmower but the rpms are not high. I have six codes going when I hooked the computer up. p0320, p0700, p0300pd, p0303pd, p0304pd and p0105. They are suggesting misfires but I changed the plugs. The check gauges light came on and is showing no oil pressure. The fuel pressure was tested and it is good. There arent any vacuum leaks. It is stalling randomly and Is not driveable. When it stalls I cannot turn it over. I turn it off and try to turn it while pumping the gas and it starts sometimes. If it doesnt I have to wait a minute or two and start it again. I am litterally trying everything people suggest. I have replaced the spark plugs, wires, distributer cap, rotor, iac valve, thermostat, map, cts, starter, computer, regapped the plugs and cleaned the throttle body. I unplugged the fuel injectors and I can take all them out except the first and last one and it does not stall. Next I was thinking about replacing the tps and the oil pressure sensor or sending unit..whichever it is. Then I was told to do a compression test. I am pretty new to all of this and am learning by asking questions and coming on the forums. I do have people helping me out that know what they are doing and we are just stumped. Ideas?? Please help!!

 

For your lack of oil pressure make sure the oil pressure sensor is secured into place. It's the placed awkwardly close to the oil filter right above it. Make sure the new sensors are actually good. I can't tell you how many times the first one you get is made badly. Their quality lately ha been horrible. Good luck with everything. Also mage sure your spark plug wires are in the correct order if you removed all of them.

 

Moved thread.

 

How badly did it overheat? It is possible that the overheating caused the head gasket to fail.

That is probably why a compression test was recommended. And I agree. Run the compression test. It doesn't take that long and a bad head gasket can often be snaked out by a compression test.

The compression spec for the 4.0 is 120-150 psi, with no more than a 30 psi variation between cylinders.

Let us know what you find.