New To me XJ Trans drag

Hola, So I just bought a 90’ XJ from a friend. He took a motor and trans from another XJ, same year and had them both rebuilt and installed himself. The Jeep ran last back in 2014. I literally drained the bad fuel and replaced it with new gas and it fired right up. Took it for a drive around the block and about 800 ft into it, it died but immediately restarted albeit a little rough. I assume it was still working out the old s**t gas. Bottom line, I put it back into drive and now it drags hard like I have the E brake on. I can put the trans on 3rd or 1-2 and it drives fine. But in drive I have to really gas it to get it to move at all ( like the Emergency brake is up ).. Reverse is good. Just let off the brakes and it’s rolls on it’s own through all the gears but Drive.

Any ideas? I’m no trans expert but wondering if it’s maybe a cable setting or of something got clogged and I need to take it in somewhere.

Thanks

90’ XJ 4.0 auto

Start with the basics, check all the fuses, make sure the trans is full of fluid, make sure the fluid is the specified Dexron-III/Mercon and NOT ATF+4, check all the wire harnesses to the transmission for chafed or melted wire insulation, and rodent damage. Make sure all the wire plugs free of corrosion and are firmly connected.

If transmission will shift manually 1/2 - 3 - OD, suspect the Transmission Control Module, wiring issues, or perhaps a faulty trans solenoid.

One would think this is my first time in any forums! I found the issue. The TCU was simply not there. I bought the Jeep and the interior is completely out of it. I did see that big ole plug dangling there but yeah, after searching I see what it is. Thanks for the reply though!!

Thanks for getting here with the cause.

Base2Final said:

.... I found the issue. The TCU was simply not there.

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Very suspicious.

Did you put in a TCU and drive it? I have driven with the TCU unplugged. I do not remember that I had any issues with it in D. And yes I drove it over 1200 miles. I could be wrong as it has been 3-5 years ago. I would suspect the NSS.

75SV1 said:

Did you put in a TCU and drive it? I have driven with the TCU unplugged. I do not remember that I had any issues with it in D. And yes I drove it over 1200 miles. I could be wrong as it has been 3-5 years ago. I would suspect the NSS.

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Yeah I drove it around my block for about a 1/4 mile. It died likely due to working out the bad fuel left in the fuel lines/filter from 2014 lol

I restarted it then put it in D, it wouldn’t drive for s**t. Drive fine in 1/2 and reverse.

I just bought the Jeep from a friend. Everything under the truck is new. Motor, trans, transfer case etc. he had gutted the interior and most of the dash and lost interest in the project. Lucky for me! Picked it up for a song but, now I’m picking up the mess. After searching I found the TCU still bolted to the dash that was in a pile in my garage lol

Plugged in, drove it again and shits normally through all gears now


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FWIW. I have since reinstalled the original trans, topped it off and she’s a runnin’ again.

Well kinda. Shifts good and all anyways but that’s for a different thread. Appreciate everyone’s help


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My wife's TJ had a clogged cat. Showed the same symptoms your describing.
If you can remove it easily, do it and go for a short run.
Hopefully that's not your issue, it was close to $600 for the replacement cat.

2003 TJ 4.0

SleeperXJ said:

My wife's TJ had a clogged cat. Showed the same symptoms your describing.
If you can remove it easily, do it and go for a short run.
Hopefully that's not your issue, it was close to $600 for the replacement cat.

Click to expand...

No cat on this heifer


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