OK, what eats CPS's??

Ok. My 98 4.0 w/ auto died on my wife and I had to tow it home. I checked the stop relay, coil, etc. Nothing. I replaced the CPS and viola! Runs better than ever. Drove a few miles and came home. Went back a little later and guess what? NO START! I though what the hey, maybe a bad CPS? SO I went back and dot another CPS. Replaced it and Viola! Runs again. Shut it off, tried to restart and NOTHING.

HELP!!!!!!!!!!!!!!

Next stop - the stealership or a deep lake!

On the up side, i can pull and replace those suckers pretty well now!

Jeeps - yum! :chef:


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Have you cheacked the connectors on the wiring? They have a tendancy or corroding and it acts like a bad CPS. Maybe your new CPS works until the connector gets bumped and looses it connection.

I checked the connectors and they -look- fine.

After the first CPS was put on, the jeep idled and ran better than it has in a year. After the second was put on, it ran not as well.

Of course, now it runs not at all.

Double check the ground from the firewall to the head. It is in the area of the cps and if open can cause multiple problems. Maybe when you did the plugging you wiggled the strap.

I'm not real familiar with anything newer than a 96 XJ. But if you can get a wiring diagram, you can check the resistance in the wires between the CPS and the engine controller. Your CPS may be operating (or not) at the edge of the envelope due to resistance.
I've seen low voltage in the 5 volt sensor supply circuit, cause what appeared to be CPS failure. Both times I've seen it, it was a short in a sensor that was draining the 5 volts down to around 2 or 3 volts.
Taking an XJ into the dealer for electrical problems can turn into a real nightmare. If it's something they've seen before it can go well, if it's something exotic it can get real expensive.