P0301/P0302..need thoughts.
 

Needing some advice on a P0301 code. 2001 XJ, 4.0L, AW4.

Here's the situation...XJ runs rough with a flashing CEL. When I pulled the code, it was a P0302. The Coil Rail was replaced a few months ago with an inexpensive one (so there is a chance its the problem). I checked the #2 injector yesterday and the ohms are 12.5. I also checked injectors 1 and 3 for comparison and they are 12.5ohms. Then I swapped injectors around...2 to 3, 3 to 1, and 1 to 2, reset CEL and expected to see the CEL move to P0303 if it was a bad #2 injector. But got a P0301 instead (What?). Installed new spark plugs, still a P0301.

So I am about to buy a new coil rail or try a new crank position sensor. I don't think it is a valve spring since the code moved. Oil and coolant are fine, so I don't believe it's a head gasket issue.

Anyone else have to go through this that have suggestions? I have read all the P0301 and P0302 threads...but none of them really ever say how they got it resolved.

My guess would be the coils . if you hook up a vacuum gauge you can see if the valves and springs are working wright . I don't think it will be crank sensor cutting out one cylinder .

so you moved the injectors and the code changed? originally it was misfire in 2. moved #2 injector to 3 and then got a misfire in 1?

idk about the coils but i presume 1 coil covers 2 cylinders. no matter what you’re getting misfires on cyl 1 & 2...? can you swap coil locations?

The 2001 has a one piece coil bar with 3 coils that run all 6 cylinders .

yes. can the coils be removed and switched? if not wtf jeep.

i have a 97 and haven’t dealt with the coil jeeps much. swapped a couple motors but that was easy stuff.

The coils are sealed in a one piece plastic housing that has one plug for the wiring and it sits over all the spark plugs .

This is the coil rail I bought from Amazon in Nov of 2017....so maybe it went bad already in 5 months. (Probably made in China, but it had good reviews.)


I just hate to go buy another one not really knowing if the problem is something else. But I might have to so I can rule it out.

I got one from a pick a part for cheap on a 1/2 price weekend and it a oem and I tested it and it is good .

Before throwing parts at it I would test all the injectors with a noid light and inspect all the wiring to the injectors very closely. The XJ's have a known chaffing issue on the injector harness where it comes around from the firewall to the valve cover, but, I would look at the entire harness to each injector very closely.

Since XJ's injectors and the coil get power from the ASD relay if the ASD relay is working fine for the injectors then I may consider the coil or wiring to coil suspect but not before checking the other items first.

Seems like many of these P301 threads die without the resolution being updated. So I wanted to update that I resolved the issue with a new set of injectors. (Decided on 4-hole)

Cherokee runs great again. :icon_cool:

Thank you for the update. They're APPRECIATED.