Cam Sensor Woes

Hi,
A person I know just bouhgt a 2001 XJ with the 4.0 and the A/T. Shortly after that the cam sensor housing that takes the place of the distibuter in the newer DIS ignition siezed up, so he put a new unit on it, Now it idles rough when its cold, but seems to have all the power it used to. He even replaced the sensor itself on the top of the housing and didnt hardly notice a difference. Does this have to be indexed like a distibuter or what? Thoughts?

Thanks,
Ethan

I cannot answer your question, specifically, since my rig is a 93, and the newer ones I know little about. This crosses my mind, though...
How long ago was your repair??? This is why I ask. The PCM has a memory for running conditions, and looses the memory of those conditions (by which it calculates the engines needs) when the computer is powerless for a period of time. The computer may memorize vehicle operation patterns from 40 or more keystarts. There is a "relearn procedure" that the vehicle should go thru if such problems are experienced just after a repair that required unhooking power to the PCM. Our rigs are so different, I am not going to imagine the procedures are the same. The procedure for the 93 XJ consists of warming up, idle in N, in P, and in D. Soft throttle accel. to top gear, cruise at half throttle, decel. allowing each downshift, and them cruising, and doing kick-downs for a one-two gear kickdown... The problem starts when the vehicle is trying to relearn it's patterns to formulate the engines needs off of, and we are out there driving erratically trying to "blow the cobbs out".

Not sure at all if this line of thinking may help, but the notion that the problem may be self-correcting with a little normal driving is an inviting thought. One may consider unhooking battery power for 30 minutes or so, and starting the relearn over...

Worse case, it doesn't work. It is easy, and cheap to try, though.

Best of luck to you.

TheRasper,

I shall relay this to him, additional thoughts are welcome.

Thanks,
Ethan

Here's the indexing procedure:

http://www.estared.com/jeep/Cam_Indexing.pdf

JLDiaz> Thanks for the info... Now I see the differences, and your line of thinking makes good sense. Not used to systems like that.... Thanks for the lesson.

TheRasper.

I must add: That's what the FSM says.
Also: the darned thig runs, even when the sensor is 180deg. off!!!

If anybody knows what to do when you don't have a scanner that can do the fine indexing, please post.

Sweet thanks for the .pdf you guys are great

Ethan