Problems with XJ starting!! Need your suggestions!

[TRAILREADYXJ]

Its going to take a bit but the next step is to go from the sensor to the ECM with every wire to check for grounding out and for continuity... i would start with your CPS wiring.. If you have a C-101 bulkhead connector thats probley a good start

This is pretty much what I've done, I am going to double check myself though.

I don't have the C-101, but my friends XJ does.
Also my cps wiring is the newer type that goes straight to the ECU (seperate of main harness). I guess that's a good thing about having one of the last year renix models.

Everything I've tested has led to the ECU, but I know it is probably the least likely thing to go bad. I am worried I may have fried my extra ECU too, since I still had a bad ICM when I tried it. I'd hate to buy another one since it can't be returned.

I am going to recheck all the wiring and sensors (3rd time). I may just have to bite the bullet and get another ECU. This is also the only thing that would kinda make sense of why both Jeeps won't start now.

BTW, the fuel pump runs fine and I get plenty of pressure. The problem is definitly in the pulse signal from the ECU to the ICM.

Now where's my meter....

 

[wilcharl]

Maybe you are hte one in a millon that fried a renix ECM. I know autozoo takes ANYTHING back including electricals ... That may be an option if you know what i mean... Or a junk yard ecm ...

 

[TRAILREADYXJ]

Well I guess I'm not one in a million...Tried a used ECU pulled from running vehicle....no luck.
Now I'm really stumped...
I'm going to poke around with this for a couple days, I'll post up anything I can figure out.
It may just be stroker or V8 time...lol

 

[serge]

I have tested the following going by the FSM and they are all well within spec.
1) CPS
I used an analog meter to test the pulse signal at module and there is none.

Did you check the operation of the CPS sensor with an analog VM? The FSM only specifies checking resistance. You should see slight fluctuations of a needle as you crank the engine. This will confirm that the CPS is sending the pulses out to the ECU.

 

[Alienspecimen]

I know your fuel pump is fine, check the connector and the harness, it takes just a few minutes.

When the car is not moving that stuff does not jiggle and you have a constant connection...this is why at the dealership was diagnosed as contaminated fuel (which I had). When you start driving it, that's when it cuts out intermediately.
BTW the mechanics at the first shop were also confident that it was definitely a spark problem...go figure

 

[wilcharl]

I would use an analog VM on the CPS at the ECM make sure that its doing its thing... and the ECM knows about it... CHECK ALL YOUR GROUNDS CHECK ALL YOUR GROUNDS CHECK ALL YOUR GROUNDS esp the one on the back of the engine by the edge of the intake to the firewall

CHECK ALL YOUR GROUNDS

 

[TRAILREADYXJ]

FIXED IT!!!

Guess what wilcharl, IT WAS A GROUND!!!
The ground to the ECU was bad.
I had previously tested power at the ECU with the harness connected and it showed power, I don't know why but I didn't think twice. It must have grounded through a sensor or something.
This morning I decided to test all the wires at the ECU for any shorts, This time I unplugged the harness, sure enough no ground. I ran a jumper from the factory harness to the firewall and it started right up.
I did have a bad ICM as well, probably a voltage spike or something when the ground broke.
It's running great now, I'd say the adjustments I made to the TPS sensor when I was testing it helped that. My idle was always a little low, but not anymore.
The most ironic thing is that I install car audio/video/and security for a living, I am always fixing bad grounds and solving power issues!!!

 

[wilcharl]

im glad its fixed.. this is my second renix no start resolved... Welll if you count my two own the 4th ... renix systems are crazy but they always plesaes you in the end... I am glad it worked out...

 

[Alienspecimen]

Glad it is fixed and thanks for letting us know. Enjoy your drive

 

[TRAILREADYXJ]

Ah, It was so nice to get out on the trail for a while yesterday. It's running great!

Thank you all for the help and suggestions!

I still need to get my friends running, but that shouldn't be too much of a problem.
It has spark, and I'm pretty sure it's getting gas, I'm hoping it's fouled plugs, or bad spark plug wires.
It's just a matter of my braving the cold to work on it. I'm glad he doesn't need to drive it soon...lol.