PCM/ECM question

[ice_cold]

I have a 98 XJ with 4.0 and auto. Not getting spark. Have replaced everything but the ecm/pcm and the distributor....
Looking to find a computer to try.
What years are compatible with my set up?

Thanks
Mike

[4.3LXJ]

The OBDII PCM from late 96 - 98 will work. I think there were some changes in 99 that will not work with your engine.

[ice_cold]

Crap there are 2 99's at the yard.....guess I am still looking.
Is there any way to test a pcm?

[XJ408]

Im having the same issue with my 98 XJ....I replace my ignition coil...thinking that would be the issue but of course not...Im thinking it would be the CPS but im not quite sure....so im going to drop it off to the mechanic to get it checked out.....

[ice_cold]

Replaced coil, CPS, plugs, cap, rotor and wires.....only things I can think off are the PCM and Distributor

[4.3LXJ]

Check engine light on?

[XJ408]

No check engine light on mine......:confused:

[4.3LXJ]

If the PCM is fried, they are supposed to throw a code 55 I think is the right number. Does the fuel pump and everything else work? Many times when it goes out you will have multiple issues and some may change over the course of a few minutes between tries to start. I would check the cam position sensor before going after the PCM

[ice_cold]

No CEL here either. Hooked up my scanner, only code that comes back is P0100, something about the MAF.

[4.3LXJ]

No CEL here either. Hooked up my scanner, only code that comes back is P0100, something about the MAF.

Those codes are there for a reason. It is telling you your mass air flow sensor is not right. Located in throttle body. It needs to work right so your fuel mixture is correct.

[ice_cold]

Thing is, I hook the timing light up to it, and turn it over...nothing. No flashing light.
Its like the coil is not getting any info on when to fire.
Fuel pump fires up when I turn the key, I wait till it stops then turn to the start position., it spins smoothly with just a slight bump in it as it spins. I n pretty much the same place.
Ok...now that I am typing and thinking...I am not actually sure the distributor is even turning.... second ..where is this Cam Position Sensor? Is that the one inside of the distributor? Any ideas on how to test it?

Thanks
Mike

[4.3LXJ]

It is inside the distributor. If it is defective, you will get no spark. They can deteriorate over time. Sometimes they just crumble when touched too hard.

[ice_cold]

And being as I just replaced the head and a bunch of other stuff that I was told was "replaced" by the original owner, I am not going to be to surprised if it is the cam sensor...time to get at it again....or find another distributor, and rebuild it and just swap it in...might be easier....but who knows.

[Weldmen]

This might be a dumb question BUTT, did you check your fuse's under the hood. I had the same problem and it was a 20 amp alternator fuse. My alt fried and popped the fuse. And no start. replaced and wammo! Still going. :pray:

[ice_cold]

Jeez...start simple mikie...did not even think of the fuses and relays under the hood....
Getting to old I guess...lol

Thanks
Mike

[XJ408]

comes to find out it was the damn CPS....:bang:

[Mudderoy]

comes to find out it was the damn CPS....:bang:

Good, that's the most common issue it seems.

[ice_cold]

Well I installed a new one so thats been stricken from my list

[ice_cold]

Checked all the fuses...all are good.
Still looking