5.2 Stalling - JeepForum.com
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post #1 of 69 Old 07-06-2021, 06:38 PM Thread Starter
Hempinfool
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5.2 Stalling

I have a 93 5.2 ZJ Engine & Transmission in an 89 YJ that I bought in 2003ish. Over the last 6 months, it has occasionally stalled/ shut down while driving and refused to start for a period of 1 minute to 15 minutes. It could be weeks between episodes but two weeks ago it quits on every drive which I thought would be a good thing.

Being bored and retired, I started the "12 Things You Need To Do When Your ZJ Stalls" by ZeeJay1997, a tune-up and gauge upgrades. As a note, there are no codes.

I removed the PCM to check for corrosion and connectors when I discovered small cracks in the case.

Is this a sign of possible failure or just old plastic?
Kinda looks like something expanded to cause them.
Is there a way to troubleshoot the PCM because I haven't seen anything yet?

Appreciate any guidance on this.

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post #2 of 69 Old 07-06-2021, 08:45 PM
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That's just plastic man. The pcm failures are usually in the soldering on the board but not common on the V8s.


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post #3 of 69 Old 07-07-2021, 01:30 PM Thread Starter
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I was kinda hoping that you would have said " Yep, those cracks are a sure sign of impending doom".
Anyway

It's back to the 12 things you need to do which is really a lot more than 12!
The good side of this is that I am learning a few things about my Heap that I have owned for a long time.

Much appreciated.
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post #4 of 69 Old 07-09-2021, 04:42 AM
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Quote:
it has occasionally stalled/ shut down while driving and refused to start for a period of 1 minute to 15 minutes.
I would replace the crank sensor.
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post #5 of 69 Old 07-09-2021, 01:02 PM Thread Starter
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I will preface the following as understanding that replacement parts aren't always in working order.

I have replaced the following
Plugs, Plug Wires, Coil, Rotor Cap, Rotor, Crank Sensor
Replaced or swapped all relays on Power Panel
Checked and cleaned all fuses.
Still working on checking all electrical connections for breakage, corrosion ect.

I am awaiting parts to install a fuel pressure gauge, vacuum gauge, and 2nd transmission temp gauge which has nothing to do with the current issue.
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post #6 of 69 Old 07-09-2021, 01:12 PM Thread Starter
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During my adventure, I found the following connector not connected.

What you see is the crank sensor connector where it connects to the harness.
The 4th wire is WT/BL in color with a single spade connector.
It looks to have been spliced to the light green wire.

The wiring diagram shows that the rest of the WT/BL wires in this location go to the following:
Crank Position Sensor, Cam Position Sensor, Vehicle Speed Sensor from the PCM with 8 volts.

Any ideas?
Due to this being a transplant powertrain, it may have never been to anything and this is my first time noticing it because I removed the PCM.
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post #7 of 69 Old 07-09-2021, 04:20 PM
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5.2 Stalling

It wouldn't start or run without the crank sensor.


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post #8 of 69 Old 07-09-2021, 04:50 PM Thread Starter
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I agree.

I was just stating where the rest of the wires that were of like color were connected to.
I'm assuming it also has 8 volts but I haven't checked yet.

I'm not the best wire diagram reader and I don't see that particular wire on the schematic.
Just seeing if anyone had any info that I can't find yet.
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post #9 of 69 Old 07-10-2021, 06:49 AM
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Do you have the check engine light installed? If so you can check for codes. With a transplant like yours i would like to see what the pcm sees. The check engine codes would be a stating point but looking a live data via OBD port would be better.
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post #10 of 69 Old 07-10-2021, 09:44 AM Thread Starter
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No Codes, I wish I had some codes.....
I have never read about a program to watch OBD1 data.
I will look into it today and see what I can find.
Thank you
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post #11 of 69 Old 07-10-2021, 12:19 PM Thread Starter
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OK
Are you referring to an Actron Scan Tool or the whole let's tear into the PCM and build stuff that data logs?
The second is over my obtuse brain.
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post #12 of 69 Old 07-10-2021, 01:08 PM
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Quote:
Originally Posted by Hempinfool View Post
No Codes, I wish I had some codes.....
I have never read about a program to watch OBD1 data.
I will look into it today and see what I can find.
Thank you
Your board maybe cracked. More likely a cold solder joint.
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post #13 of 69 Old 07-10-2021, 01:38 PM Thread Starter
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I thought of that also.
And I thought about getting a better PCM but they haven't made them in 20+ years.

So where is the best place to get a PCM?
Junkyard or somewhere with some kind of warranty...

I guess at worst, is that I would have a backup PCM if it doesn't fix it.
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post #14 of 69 Old 07-11-2021, 04:57 AM
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If you have the check engine light installed you will still get 55 code meaning "end of codes" using the key dance. The ODB port has wires that run directly to the pcm. You can get scanner that will read live data but they are usually $. You can use a blue tooth reader that shows data on your phone.
https://www.amazon.com/BAFX-Products...iglink21627-20
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post #15 of 69 Old 07-11-2021, 05:28 AM
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12 and 55 are begin and end of the sequence. Anything in between is the code you want.


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