Tracking down a 2.5 misfire

[sertshark]

1999 Tj with the 2.5. The miss is like one quick hiccup, and when it misses I can see the tach jump during the miss. It always starts right up, idles very well, and runs great, but the miss seems to happen down the highway once in a while, usually somewhere around 2200 RPM's. I noticed the miss when I bought the jeep a few months ago, and I installed new spark plugs, wires, rotor, cap and coil, but the miss still shows up once in a while (it's been worse the last week or so). I also installed a new camshaft position sensor (sometimes called distributor switchplate) a few months ago to get rid off the P1391 code I had, which worked to get rid of the code. Aside from the occasional miss down the highway, there is no check engine light, and it runs and starts great. Any ideas what I should check?

 

[sertshark]

Well, as you might imagine, as soon as I posted about the problem it got worse.... Now it's missing at idle, rather than just going down the road. And it threw a P1391 Manufacturer Control code with a check engine light. This miss has suddenly gotten worse just over the last week and now I get the error code.

 

[TokenJo]

Well, as you might imagine, as soon as I posted about the problem it got worse.... Now it's missing at idle, rather than just going down the road. And it threw a P1391 Manufacturer Control code with a check engine light. This miss has suddenly gotten worse just over the last week and now I get the error code.

Just reading through this code, it shows both Cam & Crank sensors can cause this. Was the crank sensor replaced? Also some aftermarket sensors dont play well with the jeep. Try to get OEMs or recommended ones from other forum members. Someone may chime with it? Also could potentially be a bad PCM? If the PCM wranglefix.com who is on this forum and a sponsor maybe able to help you out.

 

[sertshark]

Just reading through this code, it shows both Cam & Crank sensors can cause this. Was the crank sensor replaced? Also some aftermarket sensors dont play well with the jeep. Try to get OEMs or recommended ones from other forum members. Someone may chime with it? Also could potentially be a bad PCM? If the PCM wranglefix.com who is on this forum and a sponsor maybe able to help you out.

I changed the cam position sensor (the one inside the distributor) with a Mopar one (which seemed to clear the code for almost two months), and now I am currently looking for a cam position sensor that is also Mopar. I hate to just throw money at it without knowing for sure, but the code is back and it's missing even worse that it was.

 

[Rickyd]

Compression/leakdown tests? Faulty injector or injector wiring?