Novak Conversions Jeep Wrangler TJ engine mounts

Sporadic Engine Stall

C

Chicken_Hunter

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Jul 7, 2024
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North Carolina
Hello All,
I frequent this site regularly for information. I'd like to say thanks to those of you who take the time to help with advice, tech support, and personal experiences.
I have had my 2000 4.0L Wrangler for a couple of years now, but I occasionally have an engine stall. 99% of the time it will start right back up without hesitation, its progressed from once every month or two to about once every week or so.
When testing I noticed my fuel pressure would drop quickly after shutting off the engine, 48psi while running to less than 35psi after roughly 30 seconds (check valve in the fuel pump). I changed the fuel pump 2 weeks ago, so now I have 50-55psi while running with no drastic drop in pressure after turning the engine off (+42psi after close to an hour).
Also, I have changed my spark plugs with Autolite XP-985 and installed a new MSD coil rail.
So I am in the process of checking and replacing the usual components in the ignition system. What I have noticed is after this issue occurs, there is no CEL or codes thrown to see in my OBD tool. I even stopped by Advance a few minutes after it happened to use one of their OBD tools, just to make sure it wasn't my OBD reader. I would expect something happening that will shut the engine off, would toss out some code? But I am not an expert in the language of OBD, so I thought I should ask those who may know more about the subject.

Thanks for any information you may suggest.

Chicken
 
Inspect closely the plastic encased ECM wiring harness that runs along the firewall which is routed around a threaded head stud in the right rear corner of the valve cover. This threaded head stud is known to rub thru the plastic split wire loom and the wiring harness insulation interrupting the ECM signals when they short to ground. The interruption of ECM signals can cause the problem you have described.
On my 2001 I installed a spare rubber spark plug boot over the threaded head stud so this problem does not occur.
 
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When the vehicle dies did you notice (before the restart attempt) if any of the dash lights were illuminated? Of not then you could have the electrical portion of the ignition switch starting to fail and slowly worsening. This also would explain a no code situation.
 
CharlesHS said:
Inspect closely the plastic encased ECM wiring harness that runs along the firewall which is routed around a threaded head stud in the right rear corner of the valve cover. This threaded head stud is known to rub thru the plastic split wire loom and the wiring harness insulation interrupting the ECM signals when they short to ground. The interruption of ECM signals can cause the problem you have described.
On my 2001 I installed a spare rubber spark plug boot over the threaded head stud so this problem does not occur.
Click to expand...

I will definitely take a closer look at this. The rubber boot is worth doing as a preventative, great idea!
Thanks
 
Chicken_Hunter said:
I have already pulled and cleaned the IAC. It didnt look to be dirty but i wiped it off anyway.
Thanks for the suggestion though.
Click to expand...

Did you run a can of throttle body cleaner through its port at idle with the throttle closed?

What i should have asked was when does it die? When idling or returning to idle?

If running down the road maybe crank or cam sensor
 
swtrailboss said:
When the vehicle dies did you notice (before the restart attempt) if any of the dash lights were illuminated? Of not then you could have the electrical portion of the ignition switch starting to fail and slowly worsening. This also would explain a no code situation.
Click to expand...

I don't remember seeing anything lit up on the dash. But to be honest I was more focused on getting it in neutral and finding a good spot to pull in safely. I will definitely keep an eye out for that.

Thanks
 
Rickyd said:
Did you run a can of throttle body cleaner through its port at idle with the throttle closed?

What i should have asked was when does it die? When idling or returning to idle?

If running down the road maybe crank or cam sensor
Click to expand...

It happens when driving down the road. Cam and Crank sensors will be the next items to change. I don't think they are the issue but I don't mind being wrong either. Cam and Crank sensors, Ignition switch, and checking for any possible worn harness causing a short. Those seem like the most common items to start with.
 
Chicken_Hunter said:
The OBD scanner I have is bare minimum, is there one you guys can recommend that I wont have to trade my first born for?
Click to expand...

I use a cheap Bluetooth ODB dongle and Torque Pro...Lite which is free might work fine too.

https://www.amazon.com/gp/aw/d/B06XGBKG8X?tag=wranglerorg-20

I'd like to purchase a better model but most are based on Chinese derivatives of ancient Android builds...and as a cyber security professional I'll pass.

What and how many data points can your reader read?

-Mac
 
macleanflood said:
I use a cheap Bluetooth ODB dongle and Torque Pro...Lite which is free might work fine too.

https://www.amazon.com/gp/aw/d/B06XGBKG8X?tag=wranglerorg-20

I'd like to purchase a better model but most are based on Chinese derivatives of ancient Android builds...and as a cyber security professional I'll pass.

What and how many data points can your reader read?

-Mac
Click to expand...

I would have to dig it out to verify and recently moved so that might be a task, it was from Autozone for like $30. After replying to your message I searched online for some. Found the OBDLink website with the MX+($140) and LX($90) that are Bluetooth and the SX($50) wired version for use on most mobile/laptop/tablet devices and OBD apps. Those are much less expensive than I figured they would be. I will order the one you linked or the LX tomorrow, and start logging when driving.
I remember paying a few hundred for an OBD handheld that had a record function that was trash, and it eventually bricked too. I appreciate the info and will update here as changes are made.

Thanks fella
 
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Ultimately data is going to solve this...and a good reading of the data is cheaper than sensors that are arguably usually worse than the originals they're replacing.

-Mac
 
Novak Conversions Jeep Wrangler TJ engine mounts
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