problem solved please delete

MarineTillDeath

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Mayodan NC
Start from the begging ...

Purchased a 1997 jeep grand for the 4.0 out of it for a tj project...engine ran fine before the pull...

Put it in the tj 1998 model auto trans..

Engine started right up but had a skip with a weird rattle noise (could not determine from where....gave it gas....it cleared...

Idled for 10+ minutes


Put in reverse....shut off and would never start again. Will spin over fine and strong.

Tried everything...all sensors...injectors..plugs wires checked distributor coil ect. The jeep is getting the correct amount of fire, correct amount of fuel and compression is 130lbs on all cylinders but number one...it is 25lbs. BUT still should crank.

Timing is correct flywheel correct. Everything is new and good...

Changed the crank sensor and it finally threw a code (CPU cannot detect crank sensor) checked voltage on CPU to all three wires on crank sensor all are where they could be and I have tried 3 of them


I have taken it to the Chrysler dealership....no clue what it is...several local auto shops....no clue
.. jeep experts...no clue... I mean 30+ year mechanic vets....no clue...

It has everything it needs to run...

Now the snap on code reader when checking all sensors again said the injectors were 0.0 while spinning over...BUT I pulled the entire rail and they all work and pulsate as should..


This thing has me and 100 reputable mechanics beat....any help would be appreciated.


Thanks in advance!
 
Was the TJ a 2.5 or 4.0? Curious on what all you swapped.

I don't know why it won't run but does it even matter? It has to come apart or be replaced anyway.
 
Will it fire and run on starting fluid?
 
I do know those crank position sensors can be a PITA. Spacing is crucial for an accurate reading. Fought with many of those over the years. I have actually had to shim them before.
 
Moved to the right section and cleaned up the e-drama.
 
If you are getting spark as you say and it will not start on either then did someone leave a rag in the intake? You have to have fuel air and spark... If you have the spark and introduce the fuel, then the air is not the there. Maybe skipped time and not opening valves at the right time?
 
snappy said:
If you are getting spark as you say and it will not start on either then did someone leave a rag in the intake? You have to have fuel air and spark... If you have the spark and introduce the fuel, then the air is not the there. Maybe skipped time and not opening valves at the right time?
Click to expand...
Had the intake back off, new throttle body, took valve cover off to double check rockers lifting properly.

It's getting everything as should, lol that's why I created this thread. Plenty of air, spark and fuel
 
Here's a few things to do:

The crank sensor should be shimmed the thickness of a corner of an oil filter box. Really, it's true. Tear a dime sized piece off, stick it to the sensor with a dab of grease. When you install the sensor, push it down against the flexplate and tighten the bolt. It'll spin off as soon as the starter engages.

Measure crank sensor output voltage. It is an AC generator.

Are ALL the grounds on the dipstick stud?

Does the instrument cluster gauges move when you turn the key on?

Holler back, I know a dude who is pretty good with Jeep electronics.
 
Jody Treadway said:
The crank sensor should be shimmed the thickness of a corner of an oil filter box. Really, it's true. Tear a dime sized piece off, stick it to the sensor with a dab of grease. When you install the sensor, push it down against the flexplate and tighten the bolt. It'll spin off as soon as the starter engages.
Click to expand...
That's exactly what I did too. An issue I had one time was the dowel pins in the aw4 was missing so the trans would slip position when torque was applied and the flex plate would either be to far away to read or would literally grind the head of the sensor off regardless of how tight the bell housing bolts were.
 
Throwing something out there, maybe a 4.0 guru could answer.

The thing he said about the rattle noise got me thinking. Has anyone checked the crank end play. And if so... Can the end play be so bad as to not give the sensor a proper signal? Or even be hitting the sensor?
 
Have you had distributor out?

Also check rotor. On my yj, had similar problem. Had spark at each plug when cranking, had fuel, had compression.

Wouldn't fire or run.

Turns out the screws holding the rotor down had backed out and there was enough resistance or the rotor to turn when cranking and checking for spark but not good enough to run.

Had been doing some jumps tuning my bumpstops and the negative g's made the screw finally come out.
I landed and jeep quit. Took weeks to get it back running.

If you had distributor out check to make sure it is still at #1 when piston #1 is at tdc. And it could also be at 180 degrees off. Could be one tooth off on cam.
 
Jody Treadway said:
Here's a few things to do:

The crank sensor should be shimmed the thickness of a corner of an oil filter box. Really, it's true. Tear a dime sized piece off, stick it to the sensor with a dab of grease. When you install the sensor, push it down against the flexplate and tighten the bolt. It'll spin off as soon as the starter engages.

Measure crank sensor output voltage. It is an AC generator.

Are ALL the grounds on the dipstick stud?

Does the instrument cluster gauges move when you turn the key on?

Holler back, I know a dude who is pretty good with Jeep electronics.
Click to expand...
Agreed! It's amazing what a little diag. work can do! Lol
 
Jody Treadway said:
Holler back, I know a dude who is pretty good with Jeep electronics.
Click to expand...
I know that dude too. Saved my butt a few times. Sucks at fire wood though.
 
How much of the 4.0 harness did you swap over? I think there might be a security feature in the OBDII system that disables the engine if certain parts of the harness are missing. Google "jeep OBDII security" and see if any of the resulting hits are helpful.
 
@MarineTillDeath
I am assuming you swapped the long block over, not the entire harness. Correct?

Also, you did use the TJ flex plate I hope. The ZJ one won't work in a 32RH auto.
 
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97 and 98 harnesses are not compatible. Also need to be sure you have the original smart key, column sensor, and pcm from the 98.
 
adman02 said:
How much of the 4.0 harness did you swap over? I think there might be a security feature in the OBDII system that disables the engine if certain parts of the harness are missing. Google "jeep OBDII security" and see if any of the resulting hits are helpful.
Click to expand...
I didn't use any wiring from donor jeep except plug wires,
 
Mac5005 said:
Have you had distributor out?

Also check rotor. On my yj, had similar problem. Had spark at each plug when cranking, had fuel, had compression.

Wouldn't fire or run.

Turns out the screws holding the rotor down had backed out and there was enough resistance or the rotor to turn when cranking and checking for spark but not good enough to run.

Had been doing some jumps tuning my bumpstops and the negative g's made the screw finally come out.
I landed and jeep quit. Took weeks to get it back running.

If you had distributor out check to make sure it is still at #1 when piston #1 is at tdc. And it could also be at 180 degrees off. Could be one tooth off on cam.
Click to expand...
I have checked all of that, a guy from a Chrysler dealership in Charlotte who has been working on jeeps since the AMC days came up to check it (spent 6 hours going over everything...had him beat)
 
ol'Jeeps said:
Throwing something out there, maybe a 4.0 guru could answer.

The thing he said about the rattle noise got me thinking. Has anyone checked the crank end play. And if so... Can the end play be so bad as to not give the sensor a proper signal? Or even be hitting the sensor?
Click to expand...
Yes we have checked that
 
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