Hey Guys. I used to have a '91 Xj and I was lurking around on here for a while. I sold that, moved to NC and bought a '96 Sport. It just had the engine replaced. 108K on the Engine, 126K on the Chassis. Automatic .

I took it for a Test Spin before I bought it. Looked it over good, and it drove great. I went to take it home 2 hours later, and low and behold. It wont shift out of 3rd. It redlines and bounces me back and then refuses to accelerate. I tried putting it in 4wd "sometimes" and all I had was a ridiculous amount of clunking coming from the bottom. I stopped. Through it in 4wd "All the time" and it shifts fine up past 3rd. Any ideas? I just moved and I'm tapped financially.

 

Ok, firstly, it sounds like you have some confusion between Part-Time 4wd and Full-Time 4wd. I'm assuming your transfer case is the NP242, which has positions marked for 2WD, N, Full-Time 4HI, Part-Time 4Hi and Part-Time 4Lo?

Part-Time 4wd means you can use it some of the time. It does not mean that the Jeep shifts in and out of 4wd on it's own. Part-Time 4wd locks the front and rear axles together and should never be used on dry pavement or where traction is guaranteed. Doing so will probably lead to driveshaft binding during turns, or if your tires aren't the same size, ect, and isn't particularly good for the transfer case. Driveshaft binding will make horribly loud banging noises.

Full-Time 4wd means you can have it on while driving down the road, the transfer case will allow some slippage between the front/rear axles so it doesn't bind up. However it isn't recommended to drive in 4wd if you don't actually need it.

As for the not shifting, I'm not sure. Could be the transmission range sensor, but I'm not really sure. It's also possible that the transmission downshift cable is too tight, you could try disconnecting it from the throttle body and seeing if that has an effect. Most likely you'll have to take it somewhere to have it checked over. These transmissions are pretty bullet proof, so it's most likely some sort of sensor.

 

Ok, that makes sense. Would the part time bind just back up on the pavement? I hopped in it to run down the road to the store and see if I could coax it into shifting up for me. I had left it in 4wd full time because that had stopped the slipping. However, When I got in to go take it out, the 4wd fulltime light had gone off even though it was in 4wd. I threw it into 2wd, and then 4wd FT again and it read simply 4wd PT. I couldn't get it to acknowledge I was in 4wd FT. So I threw it back into 2wd to try it and now it's shifting fine.

Could this be an ECM issue from when the engine was swapped?

 

If you don't live on a muddy or gravel road don't use any 4wd! Your probably binding
up the transfer case so bad that the transmission is being effected.

 

Then you don't have a trans issue. Try adjusting your t-case linkage, and check the bushings for it. Wouldn't hurt to check/change the t-case fluid either. JMO

 

Yeah that's what it sounds like to me, if you are selecting 4WD FT and it's showing as PT, then the linkage is probably out of adjustment.

And yeah, driving on pavement in Part-Time can cause it to bind. If the front wheels spin faster or slower than the rear, either because of turning or slightly different tire sizes, it'll bind since the tires can't slip like they would on a looser surface.