Why won't it go?

[Mike]

My friend has put a 4" lift and 33" tires on a 6-cylinder TJ with automatic tranny. Both diffs are open; no lockers. She thinks that the diff gears have been upgraded but I am not so sure. Anyway, she has trouble occasionally on uphill grades and in getting over obstacles. She can give it gas (even flooring it sometimes) and the tires don't spin or even move. The engine is straining but she isn't going anywhere. Any ideas on what the problem might be? Seems like if the gears needed to be upgraded, it would at least stall... ???

[Mtbikbob]

I am not a auto transmission mechanic, and I'm sure others will chime in with good things to look for. However, if it is doing this on inclines only it could be fuel related. What year jeep? Carburated or injected? Could be just starving for fuel. Check the obvious items, such as engine oil, tranny fluid. Not sure about jeeps all together yet, but in a chevy engine, low oil levels will keep the engine from revving.
Good luck.

[Dukes69]

Auto trannys wont allow an engine to stall, or rather they are not suppose to let them stall. First find out what gears the Jeep has. *Most* auto TJ's have 3.73's, which isnt a horrible gear for an auto on 33's, but it would be good to upgrade to 4.10 or 4.56. check the gearing and post back.

[mr.wolf]

how well does it run while driving normaly down the road?

[swbooking]

Seems like its the torque converter, i drove a ford focus for a while and on an incline sometimes if i was flooring it, it would like let go and the motor would rev but it wouldnt go and i just had to let the RPMs come back down and then itd grab again. I dont think its fuel cause the said the engine is still straining meaning its on and go, no fuel would = motor off.

[Mike]

Thanks for the ideas so far. Rather than clipping everyone's post, I'll try to respond by the topics by person:

Bob: She had just had the vehicle serviced and the fluids should have been checked according to what she told me. I took her word for it. The engine is injected and I didn't notice any roughness in the running of the engine. Jeeps with high mileage are prone to fuel pump problems, but hers isn't high mileage (unlike mine).

Duke69: She doesn't know what gears she has. A friend thinks that they were upgraded but no one knows for sure (purchased used). I think that the gears are stock. The reason I think that is that she needs a lot more momentum to get over obstacles than I do with my 4.56 or a friend's Rubi with 4.11s.

Mr Wolf: (Cool Handle) She uses it as a daily driver and hasn't complained of any daily use issues. But I need to ask her specifically. I'll see what I can find out.

swbooking (Allen): I have been leaning toward the torque converter on the grounds that if the engine is spinnning but the tires aren't, the only thing that is in between that will let the torque release is the torque converter. I have not had any dealings with torque converters in the past so I am not familiar with there workings. Any insight is welcome.

Thanks for your thoughts, and look forward to your responses,
Malachi

[mr.wolf]

Thanks for the Handle Comment.

[mr.wolf]

I'm a autotech student, in the middle of the taking autotransmission class, so just ask away on some stuff and i might be able to help.

[swbooking]

My uncle has a Tranny shop in Hawthorne, its not too far from you, im sure he could check it out for you. Let me know.
-Allen

[Mike]

Okay... I My Spaced my friend and she says that she bought it new in 2004 (sorry, I thought it was used). She had a friend in the industry do the lift and other work but I am pretty sure that she is still pulling on the stock 3.73s.

So Duke69, does this help? I know that she needs a lot more momentum that I do (with 4.56s) to get over the same obstacles. Could the auto tranny let the power slip that much with lighter gearing?

(For Bob) As for the fluids, she had just had all the fluids checked at a service prior to our last run. She does not have any trouble on paved roads at starts or any other time.

Mr. Wolf, could you check on a couple of things: Can a torque converter go bad? If so, what are the signs?

I really appreciate the input. My friend 'wheels with us on a regular basis and she is a pretty good driver. I hate that her rig sometimes doesn't react like she wants and needs it to do.

[Dukes69]

So Duke69, does this help? I know that she needs a lot more momentum that I do (with 4.56s) to get over the same obstacles. Could the auto tranny let the power slip that much with lighter gearing?

It might be better to have your friend join here so we can get the details from the source. Not saying you're doing a shitty job, but it might be eaiser.

All the problems you have listed are side effects of large tires and improper gearing. I had an 88 cherokee that had 33's and 3.55 gears. when heading up a hill I had to build up alot of speed (75 MPH) and MAYBE I would crest the top doing 35-40. Thats just how it works.

[mr.wolf]

The only components in the TC that can go bad are the stator, and the Lock up clutch if applicable, and the tranny will go out before this happens.

[Mike]

Thanks!

Thank you to everyone on this.

Duke69, I will try to get her to join the forum and pursue this herself. She loves Jeeping as much as I do so I know that she would like the site. I just need to convence her to not be shy.

Mr. Wolf, that helps. based on what you are telling me, the TC should not be an issue. I will try to get her to tell everyone about the issue herself. If not, maybe I can get her to go to Allen's uncle's tranny shop. Obviously, the one she is usng can't figure it out.

Thanks again to everyone.

Malachi

[swbooking]

Just let me know man and ill give him a ring.

[Dukes69]

I just remembered something, When I first got my TJ it had a horible grinding sound, which I was told was the tranny by the previous owner. So I too it down to AAMCO for one of their free trans checks. They said nothing was wrong with the trans, but the rearend was hosed. I don't know if AAMCO still does this, but its worth a shot.