My jeep has no power, why (rookie needs help)

[onyx maximus]

I have a 88 Jeep Cherokee with an 89 4.0 and trans in it with about 130,xxx miles on it. I has 3in of lift on 30, I have replaced starter, radiator, power steering pump, water pump, alternator, o2 sensor, basic tune up stuff and many more small things and it ran great for awhile, but now after about 35mph it belay wants to move, ill floor it and it will reeve up for a bit and then make this no power moan sound, I took it to a shop to have the transmission rebuilt and that didn’t help, I don’t think its a fuel problem but not sure taking it in today to get fuel pressure test and vacuum test, does anyone know what’s wrong with my jeep.

 

[bigdaddyjlove]

Problem is a little vague.

Fuel filter? (pressure could still look fine, but no flow)
Main bearings
Accessory bearing going out? (A.C., P.S. Alt.)
Just low compression?
Burned plug wire or two?


Any more detail you can give will help

 

[bigalpha]

TPS?

 

[onyx maximus]

I will start trouble shooting more tonight, some more info when I put it in 3rd it does fine and it has a new fuel filter. Is there a way to test the TPS or see if its not working, don’t really know much about it, but the main problem is when I have it in drive I can floor it and it will barley move, but other times it will do pretty good. The motor sounds great, doesn’t nock or anything, thanks keep the advise coming.

 

[bigalpha]

I don't like to be "that guy", but search for the TPS testing procedure.

 

[antalus2]

mine has just started doing the same thing,, its a 1990,,, i havent done anything yet but i was thinking fuel pump.. itll be interesting to see this thread.

 

[joe_peters]

Unplug the TCU and drive it, shifting manually, and see if the problem persists.

 

[winterbeater]

I have a 88 Jeep Cherokee with an 89 4.0 and trans in it with about 130,xxx miles on it. I has 3in of lift on 30, I have replaced starter, radiator, power steering pump, water pump, alternator, o2 sensor, basic tune up stuff and many more small things and it ran great for awhile, but now after about 35mph it belay wants to move, ill floor it and it will reeve up for a bit and then make this no power moan sound, I took it to a shop to have the transmission rebuilt and that didn’t help, I don’t think its a fuel problem but not sure taking it in today to get fuel pressure test and vacuum test, does anyone know what’s wrong with my jeep.

Sorry to bum you out, but my advice is to not try to make your own diagnosis. It already cost you a tranny rebuild. And you obviously don't have either the desire or capability to test it yourself. Find a good mechanic you can trust and let him figure it out from scratch. Making guesses and telling the (hopefully) trained and experienced mechanic what to test or repair will just be wasting your time and money. If YOU want to test and replace things yourself, this forum IS the best place to come for advice. You might even be able to ask for advice on a good XJ mechanic in your area. But let him do his job without your interference.
:soapbox:

 

[JJacobs]

Ditto.. instead of taking it to a shop and telling them which tests to run, just have them diagnose it. No offense but you're all over the place here and replacing every part on it doesn't help resale value much.

 

[magimerlin]

Keep in mind at about 35mph is when the torque converter locks up going into overdrives. After you "floor it" and the rpms settle and you are still over 35 mph it will go back into overdrive and lock the converter up causing a drop of about 300-500 rpms.

Instead of putting the shifter in "D" try putting it in "3" and see if it still does it.

 

[JJacobs]

Torque converter lockup and overdrive gear are two completely different things.

 

[magimerlin]

Torque converter lockup and overdrive gear are two completely different things.

Sorry...... I was tired when I wrote that so let me rearrange a couple of my wordings.

The torque converter locks up at around 35 mph or so that's a giving while in the overdrive gear selection. This only happens while the gear selector is in the "overdrive" spot. So try and put it in the gear selector "3" spot, overdrive and the torque converter lock-up will not happen in this gear selection.