I have an '03 Jeep Grand Cherokee that has twice had issues with hesitating while driving (like it’s not getting gas–tank is full), then starts rattling, then dies. I had it towed to the shop 3 weeks ago. “loss of cam or crank sensor misfire codes found loose connection at pcm, connector 4, re-attach connector to lock position, erase codes”. Picked it up after work was done. When driving it to work two days ago, the same exact situation presented. Had it towed again to shop. They’re saying they ran it all day and cannot get any codes to come up and that 90% of the time it’s the cam sensor. He also said 1/3 of the time (math issues) it’s the computer. How can you know if it’s the cam sensor or the computer?
Cam sensors don’t cost that much . Replace it & see if your problem goes away .
Does your copy of the shop order list the exact codes? What were they?
Was this shop a chain shop? An independent?
Did he test anything else?
While I understand sloepoke’s response, it may be less costly to just let him try it and see if it works, there are too many tests he didn’t do, such a checking the fuel pressure and putting an engine analyzer on it, for me to feel comfortable agreeing with such a wild guess.
The only times I have seen the computer replaced on one of these is when the problem is misdiagnosed, the computer is not the problem.
The problem is likely a failing crankshaft position sensor. Replacing both cam and crank sensors might be cheaper than another tow. Is this a 4.0L or 4.7L ?
Nevada-545, I just spoke with the shop owner (this is an independent shop, and no codes are presenting) he said that he’s had it running hoping it would stall and repeat the problem so they could get a code. Nothing yet. I’d had the hazard flashers on while I waited 2 1/2 hours for the two truck, so the battery was dead. He said he charged the battery and it started right up. It could be another 3 weeks before it happens again and he can’t diagnose it until it happens. When I repeated the symptoms to him, he said it could be a fuel pump, but he’d hate to have to charge us $500 to replace the fuel pump and that not fix the problem. Right now, I think rather than let it sit in the shop, we’ll pick it up and drive it locally to see if the problem repeats. He said if it quits nearby, he would come out to the car and check it out. Not sure if AAA will tow us again so soon. Oh, and honestly, I don’t know if it’s a 4.0 or 4.7L.
[The shop tech said ] 90% of the time it's the cam sensor. He also said 1/3 of the time (math issues) it's the computer
I suppose towards explaining the surprising math it could be both the cam sensor and the computer sometimes.
My guess, something heat related in the ignition system. Nevada’s suggestion to take a flyer and replace both the cam and crank sensor seems like a reasonable bet.
If I had this problem when it stalled I’d do a test of the ignition system for spark right then while it wouldn’t start, on the side of the road. Once narrowed down to the cause being definitely lack of spark, that makes finding a solution a lot easier. If replacing both sensors doesn’t fix it, consider to ask your shop tech if there’s a simple way you could enlist yourself as a deputy-shop-tech-on-site and check for spark yourself next time it happens.
If the Jeep has the 4.0L engine I would suggest throwing this part at it
When making guesses it’s wise to start with the cheapest and easiest possibilities and that piece is the cheapest likely cause of the problem.