Alright its been about a week already with this car and I am starting to loose hope for it.
2000 xj 175,000. 49psi fuel while cranking.
I can hear pump prime, ASD relay has been bypassed, swapped etc without any help. All fuses are good.
-Checked main sensor ground splice in harness everything is tight and clean.
-Triple checked all connections
-Opened up PCM to check for water/dirt, nada.
-P1492 batter temp sensor (under battery)
was touching both leads together I have since removed it for now.
What could possibly be left here to cause no spark?
New:
CrankPS, CamPS, coils, plugs gapped at spec
Data:
Crank sensor- 5V power, 5V signal (key on and crank)
No broken/chopped up wires from what I can see laying under the car.
Cam sensor- 5v power, 5V signal (key on and crank)
New synchonizer was clocked when installed car ran great.
I put cylinder #1 TDC and readjusted just to be safe nada.

Coil Connector-
From left to right here are the 4 pin readings while cranking
2.0V, 0.5V, 14v, 1.3V.
Is this what I should be seeing at the coil rail connector?
Somebody please give me some insight I am unemployeed right now and cannot afford to take this to a mechanic.

 

Try detaching the connector from your Coil Capacitor and see it will start.

Read to the end of this thread.

http://www.jeepforum.com/forum/f11/c...4-0-a-1492751/

 

Just tried it^ Nada.

Now I am wondering why the hell that capacitor is even there?

 

70 views 1 reply really? lol

 

Is that with your meter referenced to ground?
One pin is battery voltage (14v). You have 14V there so your ASD circuitry is working.
The other three are the PCM coil drivers. They connect each of the three coils to ground momentarily to fire the spark. Try measuring the voltage there while cranking with the (+) test meter lead on battery (+), probe the coil driver connectors with the (-) test lead. Need to see if they are switching on/off ground as they should.

The coil capacitor does a couple of things including stiffening the coil input voltage and absorbing spikes that could damage other sensors.

 

Yea that was with the meter black lead on the battery negitive.
Here are the results with the meter red lead on battery positive and black lead on coil connector

All pins showed battery voltage before cranking at key on.
I am using a Fluke, so not sure if it would show on and off (since it happens so quickly)
But it showed pretty much steadily up and down. I am listing the maximum voltage of each here

While cranking
Pin 1- 9V
Pin 2- 12.19V
Pin 3- 0.02V
Pin 4- 11.5V

 

Did you check voltages with the connector unplugged, or backprobe it while plugged in?
Two of those coil driver voltages are not dropping nearly as low as I'd expect them to, but they are at least dropping. Had they stayed at battery voltage or dropped to zero we'd have at least found a definitive problem. Rats.
If you have a 12V test light, try connecting that between each of the PCM drivers and battery (+). You should see flashing as the engine cranks. LED test light works best.
If it does not, and you are certain the CPS is in working order and it has continuity to the PCM plug, (checking resistance wouldn't hurt) next thing in line might be the PCM.
The PCM does have a nice solid ground connection? Clean connectors?

While there isn't a really good way to test the coil rail, you can check the primary resistance of each coil by measuring resistance between pin 2 (battery supply) and each of the other three pins. 0.7-0.9 ohms would be normal.


eta: forgot to ask- any codes stored? Is the CEL on? Anything unusual happen leading up to this or did it just up and die?

 

I did this with the connector unplugged.

Darn! I have been looking at this so long, But like I said these are the highest voltages recorded not the lowest. But even still the lowest werent that close to 0 from my memory.

Would you happen to know what connector this is on the PCM? I was looking for this info on numerous wiring diagrams and couldnt find it?

I cleaned the connectors but have been thinking this for a little while, The PCM grounds to the chassic via where/what?

Well heres a short summary;
Got stuck in a snow bank, spun it in 2WD at high RPM for a little longer than I should have. And when I let off the gas it stalled right away and refused to start back up.

It has previously stalled after a period of high RPM tire spin,
(recently converted to 4wd and ran fine for about 3 weeks, but no front axle as of yet so its still staying in 2WD for now) but usually it started back up. (not always right away, period of cranking)
P1492 for the battery tray sensor? The sensor wires were all a mess and might of been contacting one another, so I removed it and left an open conector for now. (shares same common ground as other sensors, will this affect anything?)

 

PCM Connector #1

 

PCM Connector #2

 

PCM connector #3

 

Battery Temp sensor:

 

You were seeing lower voltages on the coil drivers when you cranked, rising back to battery voltage when you stopped cranking? We'll call them good for now then.
Next things I'd check are coil resistance for each of the three coils and continuity from the CPS signal connector to the PCM.
Have you noticed if the injectors are firing? Noid light works to check, else you can feel them & listen for clicking while cranking.

 

Well thats pretty much useless for me right?
I am using an external adjustable regulator
(previously stereo stuff in car)
Charging voltage is 16.5V resting around 14V.
I have been fine for the past year and a half, but could this possibly have had some bad affect on something?

Not sure how to do this, i.e which pins?
But I compared random ohm reading I took from pin to pin to my OE coil rail and they were the same maybe 0.1ohm off the new one.

Just checked it is 0ohms for crankPS.
Also checked the camPS and got 0.7ohms.
Is that an acceptable tolerance?


Yea I am pretty sure (not positive) they are alright.
Fuel smell is strong through out my garage from all the cranking

 

Thanks alot for those diagrams by the way I will save those for the future they are greatt!