Novak Conversions Jeep Wrangler TJ engine mounts

2000 Jeep TJ Engine Stalling Issues

nfaust1257

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Jan 2, 2025
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Location
Ohio
I recently did a few different projects on my 2000 Jeep TJ 4.0L Automatic, one after another. Changed out radiator (old one was leaking), transmission pan (old one dented), cleaned battery terminals, new spark plugs and engine oil change. While doing this work I was able to start the jeep in park / neutral with out problem.

HOWEVER, my issue started a few days later when I decided to go on my first drive since doing this work. I started my Jeep and put it into R, to which I was able to move about 100 ft before the engine stalled, I started the Jeep back up and drove it 100 ft back into the garage and turned it off. A few days later I went back out to the garage to investigate what the issue was. I started the Jeep and put it into R, it stalled right off the bat. I started it again and put it into drive it stalled immediately. The Jeep can only start and stay running in N or P, it idles well and will not cut out in those settings, I give it gas and the engine responds to it well. After a few times of the engine cutting out the check engine light came on. I do not have a reader but have one being shipped overnight from Amazon. Ill be using it to read the code and will report back first thing in the morning.

After reading several articles on this website I decided to take the throttle body off the Jeep and clean it, the IAC control + housing. After re-assembling, I started the car and till had the same stalling issues when putting into gear. I did some more reading and found out that some people were diagnosing this same issue as a Torque converter problem on their Jeeps.

Once I read more about what the Torque converter it had me thinking that maybe I had caused this issues + broke the TC when working on my transmission pan. I say this because when replacing my trans fluid pan I opted with the new high cap skyjacker pan as it was the only pan I could find for my transmission. After reading reviews I was told it would fit fine. However I found that in order to get this pan to fit in-between the transmission and the skid plate I had to remove the skip plate bolts, which I found out to my amazement was also the transmission mount. The mount dropped with the plate for a while before I was able to get a jack to lift it back up. After getting the transmission pan in, I bolted the skid plate back up to the frame. This period where the transmission was un-supported has me thinking that maybe I had put to much strain on the TC and "locked it up".

My questions to the group would be:

1. Do you agree that this could be a torque converter issue?
2. Could I have damaged this part when I changed my transmission pan and accidentally left the transmission un-supported?
3. Any advice on what you would do next to start diagnosing or fix the problem?
 
Morning, the transmission oil was filled up all the way (correct level) with ATF+4. I found the code that is causing the check engine light this morning, as P1391 (image below of code). After some reading I am going to be replacing the crankshaft and camshaft position sensors. I saw that Chris posted the below two links on how to go about the replacement that I will be following. Ill have updates by next week on if this fixed the issue or I am still searching for my culprit.

Jeep TJ Wrangler Crankshaft Position Sensor Replacement
Jeep Wrangler TJ Camshaft Position Sensor Replacement
IMG_9738.PNG
 
I ended up taking the leads off the battery yesterday to rest the the computer, I wanted to see if I was to restart the car would any codes be thrown. To my surprise the Jeep started right up and without issue. Since disconnecting the battery, the code P1391 has not appeared again. As it stands the jeep has no codes and will start and idle, however once put into D or R the car stalls. There is no jerking movement no indication that it has even shifted, only that the engine cuts out.

I think this is now beyond my skill set and have called a transmission specialist to help out. On Thursday I will have the jeep towed to the shop for a diagnostic and repair, they informed me that if it is a torque converter issue they will most likely decide to rebuild and replace the full transmission at around a 3K cost (over the phone est before car has been seen very rough quote) best case is I messed something up when I lowered the skid plate and they just need to re-line it or the torque converter is locked up. Hoping for the best here as this is my first Jeep and only been able to drive it about 50 miles.
 
If the engine is starting and idling properly it's unlikely a sensor is the cause of your issue. Before you drop possibly $3K I would go back over your work and take a look see. I'm thinking when you dropped the trans unsupported something got messed up and is in a bind. Support the trans, remove the 4 trans mount nuts at the skid plate and then drop the skid. Look around to see if there is something obvious bent, wires pinched etc. Check the driveshaft yokes and u joints. Check the shift mechanism linkage, both trans and transfer case. Something might be bound up. You could disconnect the driveshafts and see if it will shift into drive / reverse without stalling. Perhaps start first by just jacking up the rear wheels off the ground, make sure you are in 2 wheel drive, chock both front wheels, then start the engine and put it in drive and see if it spins the rear wheels, or stalls out.
 
I ended up double checking all my recent work as suggested. It came down to the radiator cooler lines being plugged. I found that the used radiator that I installed must have had a bad transmission cooler. Once the trans cooler lines were unplugged from the radiator, I was able to put the jeep in R and D without stalling. I bought a new radiator and replaced the broken one. This fixed my major problem of stalling when put into gear. Now I am working on fixing the next engine issue. Its hard for me to describe but when put into D and the Jeep will move forward, if given a little gas I can accelerate. However, when trying to get up to any reasonable speed and pressing on the gas the engine seems to stop responding and maintains a lower RPM, then stalls out. I can restart the engine no problem, I found it interesting that when in N I can press the gas and rev to a high RPM, but when in gear it seems the Jeep will resist and stall.

To work on fixing this problem I replaced the camshaft sensor, cleaned IAC and throttle body then did a intake manifold leak test. Leak test came back good and the camshaft sensor replacement did not fix the problem. I double checked the engine oil level and Trans ATF+$ level both which were good.

This weekend I plan to replace the crankshaft sensor, test the fuel rail pressure.

Other tests and work I plan to try include: TPS sensor replacement
 
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Novak Conversions Jeep Wrangler TJ engine mounts