Hesitation in reverse only???!!! WIERD

I have a 90 4.0 AT W/ NP231 29 spline 8.25 about 4.5" lift and 31's
My jeep has been sitting for about 3 days, got in this morning, started fine, I put it in reverse and its fine @ idle speed but once I hit the gas it hesitates. I figured it may just be cold and had been sitting a few days. But once in drive it seemed fine. I drove to work with no problems (about 30 miles or so) when I went to back up it had the same hesitation. I have done a lot of automotive work and have never heard of this. Anyone else???

Might check the fluid but I would say the trans is going out. ...Ours had that problem and we had a leak around the tourque converter. Suburban did the same thing and it was a crack in the housing.

the fluid seems fine and i checked all lines connectors. It doesn't slip and reverses fine till I tap the gas, can that still be the trans? it doesn't seem to bind up or anything just acts like poor fuel pressure or bad spark.

also has no leaks unless internal.

Sounds more like the torque converter..

i will check it out thanks

I've seen the CPS or O2 wiring burned through on the exhaust and the engine torques a different direction in reverse, causing a short.

Not so weird....mine does it too....90 XJ AW4 242j TC 21 spline..........e-1 tells us that is tranny on its way out.......the tranny works fine...no slippage, leakage......ENGINE will not take gas in reverse, will idle in reverse ok....but hit the gas and it will hesitate or die......mechanic thinks maybe TCM prob, TPS has been replaced.....maybe converter locking/unlocking....doesn't seem like it though.....in shop now for TC and flywheel replacement....will keep you posted.

definitley let me know, my jeeps off the road cause I don't have cash to try replacing the TC or TCM unless its the problem.

anyone?

check your tps.

My 1996 4.0 auto is doing the same thing but in DRIVE!

I have new:
battery
iac
plugs, wires, cap and rotor
ign coil
both O2 sensors
fuel filter
air filter
clean throttle body

I put a fuel pressure gauge on it - and it held 49-51 psi the whole time = i dont think its a fuel pump

PLEASE HELP

OK. i just installed a brand new CPS and the problem got WORSE!?

now it barely runs at all....park, neutral or drive.....


HELLLLLLLLLLLP!!

My 90 with AW4/ 242tc used to do the same thing. Brought it to the shop to have the TC replaced (to lazy to do it myself), when he tore apart I got a call from him telling me I had a badly cracked flex plate. Replaced the flex plate and TC, it was in better shape than my old one
The only thing I can think of that could have corrected the problem is, the CPS was removed(and cleaned up) and reinstalled , the flex plate was replaced, a bad flex plate can make the CPS act up, and the day b-4 it was brought to the shop I adjusted the TPS back to spec.
I'd look to one of these.

ok. I decided I was better off with the old CPSas the new one (standard brand) wasnt working AT ALL!- Jeep dealership was closed on Sunday today.

I checked the old CPS with a meter and it was within spec (O Ohms between pins B and C or the middle and right if you are looking at it with the clip on top).I then wiped down the old CPS and installed that back on.

the jeep runs good again! maybe not perfect....but a lot better. no more hesitation in drive.

I noticed the way the OEM has the CPS wire harness run it was REALLY close to the exhaust manifold....and I think when it got hot (very quickly) it would throw off the CPS.
I think perhaps when it was in DRIVE, as opposed to neutral or reverse, that the engine might have leaned over to the one side a bit and made the exhaust heat problem even worse.

I took the Jeep for a quick drive and it seemed to be fixed. I hope so, because I need it to get to work tomorrow.

Tomorrow I will return that $88 CPS back to the store.

Could a little bit of dirt on the tip of the CPS and hi heat on the wiring mess up the way the engine runs this badly?? guess it did...?

NOTE: when i reinstalled the sensor, I added some heavier duty split wire loom, and re-reouted the wire harness as far away from the exhaust as possible...which was difficult because the wire harness barely reaches where it has to plug in!