Wayne Posted April 17, 2017 Share Posted April 17, 2017 Hello: I have a 95 YJ with what I believe is a PCM issue. I bought the Jeep recently. The previous owner crossed some jumper cables and blew the computer. I was able to get the Jeep running but it would not charge the battery. I got a used PCM off ebay (same exact numbers) and plugged it in. The voltage went right where it should be. The Jeep starts fine, runs about 3-4 minutes just fine, then starts stumbling, mild backfiring, etc until it reaches temp. Once it hits temp (200...then the needle backs off to 190) it starts running perfectly fine again. This leads me to believe I have an open-loop issue. It seems like once it gets in "closed-loop" it runs fine. I may not be understanding all of that 100% however. I can replicate this problem each time I start the Jeep. The only mechanical I have done to the Jeep so far is replace the O2 sensor just behind the header. Thanks for any input! Wayne Quote Link to comment Share on other sites More sharing options...
Administrators Moses Ludel Posted April 18, 2017 Administrators Share Posted April 18, 2017 Wayne...This system is OBD and can be scanned. Are you throwing any codes? An inexpensive scanner with Chrysler/Jeep adapter would be helpful here. Do you have an engine check light on? Check the TPS voltage and also the temp sensor. Any errors here could cause the stumbling. There is a list of other possibilities, but I would start by reading stored codes and checking ohms resistance at the temp sensor (at various coolant temperatures) and the idle and WOT position voltage readings of the TPS. You'll clear stored codes by disconnecting the battery. The consistent events you describe should show a fresh error if you have access to a scanner and adapter. Moses Quote Link to comment Share on other sites More sharing options...
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