What sensor would tell ECM to not allow spark?

[Lee's Automotive]

These will run just fine without the CPS. It’s not needed to spark, or fire the injectors.

Ok my bad i just seen it in another thread as a possibility

 

[Mbrooks420]

I ran for about 10k without a CPS installed. Started and drove fine.

 

[Lee's Automotive]

I ran for about 10k without a CPS installed. Started and drove fine.

Nice to know I learns something new everyday

 

[Mbrooks420]

If I’m not mistaken the CPS fine tunes the injector timing? If it’s not there, or out of range it just runs off a precanned table.

 

[donalds]

This whole mess screams broken wire in the crankshaft position sensor harness just my opinion
It will test fine with a meter but any sort of load or vibration will make the signal intermittent

 

[C420sailor]

So this is something that got worse with both heat and time

Agree with @donalds

 

[DannyW]

Was the ignition coil changed - didn't have time to read all the way back. There are 2 coils, horizontal and vertical harness exit.
My 95 & 96 4.0 OHV's take the horizontal. I found the vertical wire connector won't work by accidentally ordering the wrong one a while back. I did find out that you can re-pin the term's in a pinch.
-Dan

 

[Lee's Automotive]

This whole mess screams broken wire in the crankshaft position sensor harness just my opinion
It will test fine with a meter but any sort of load or vibration will make the signal intermittent

I agree

 

[Mbrooks420]

Was the ignition coil changed - didn't have time to read all the way back. There are 2 coils, horizontal and vertical harness exit.
My 95 & 96 4.0 OHV's take the horizontal. I found the vertical wire connector won't work by accidentally ordering the wrong one a while back. I did find out that you can re-pin the term's in a pinch.
-Dan

Everything trivial has been changed.

 

[Postal_Dave]

I'm going with Donald's theory. Let me know what you guys think of this idea. If I take the cover off the computer's harness and put two pins in where the wires for the CKP goes, then run a new set of wire directly from the CKP, would that work?

 

[Josh P]

Grab a computer harness out of a junk yard. It would allow you to cut it up, power the ecm up outside the vehicle wiring, you could connect sensors one at a time, etc.

 

[Lee's Automotive]

Grab a computer harness out of a junk yard. It would allow you to cut it up, power the ecm up outside the vehicle wiring, you could connect sensors one at a time, etc.

Thats the best idea

 

[Josh P]

Thats the best idea

A spool of wire and a box of 2 wire Wagos. Quick and dirty troubleshooting.

 

[Lee's Automotive]

A spool of wire and a box of 2 wire Wagos. Quick and dirty troubleshooting.

Oh yeah wagos FTW

 

[DannyW]

Everything trivial has been changed.

My point was about the correct coil connection, they don't interchange.

 

[Mbrooks420]

The problem would have originated with the coil change, and not been an existing problem that a coil replacement had no effect on.

 

[Runnin'OnEmpty]

I can confirm loss of cam signal will shut down an OBD ll (Jeep). I believe it only times the injectors though, and not spark. Loss of signal will definitely set a code.

What is so exasperating is there's no code.

 

[Runnin'OnEmpty]

In the first posts, I remember it starting a couple times; shutting down when it warmed, and then no grounding to the 3 coils but 12v to the coil power wire.

I know you've already checked them, but I keep thinking of relays, specifically the ASD relay...

 

[Mbrooks420]

I can confirm loss of cam signal will shut down an OBD ll (Jeep). I believe it only times the injectors though, and not spark. Loss of signal will definitely set a code.

What is so exasperating is there's no code.

This isn’t a Heep. These will absolutely run with the CPS completely out of the system. It will definitely set a code.

 

[Runnin'OnEmpty]

This isn’t a Heep. These will absolutely run with the CPS completely out of the system. It will definitely set a code.

Oops, I missed your earlier post on driving without a working cam sensor. We can rule that out then.