shifting werid

when im at crusing speed my cherokee makes a skipping action like it wants to shift but i wont. its really anoyying when driving and its starting to worry me. anyone have a clue what could be going on?

What year and motor?

yeah mine does the same thing. It almost feels as if mine is trying to shift into OD but then gets confused and stayes in 3rd. Im not sure if this is what it is doing but I have always felt it right around 40-45mph...havent noticed it at speeds much lower than that. I have a 4.0 and aw4.

My 88 4.0, used to go thunk thunk thunk at around 2000 RPM, I won´t share all the things I checked, but it turned out to be the 02 sensor was leaning the motor down to much at that RPM in high gear (fairly low vacuum). Noticed it the most when mildly accelerating in high gear. Almost felt like the TC was locking and unlocking.

so you are saying that the oxygen sensor was at fault? I know mine needs to be replaced because at idle it was running rich and it just hardly passed emmissions as it was high on Hydro carbons and my gas milage is down the tubes. hopefully once that is replaced everything will go back to normal!

scase86 said:

so you are saying that the oxygen sensor was at fault? I know mine needs to be replaced because at idle it was running rich and it just hardly passed emmissions as it was high on Hydro carbons and my gas milage is down the tubes. hopefully once that is replaced everything will go back to normal!

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It´s what was causing my problem, motor would lean out and stumble at around 2000 RPM, sometimes pop a little out of the TB. I checked a whole bunch of stuff, just on a hunch one day, popped in a spare 02 sensor and the problem disappeared.

My guess is it is a bad tps. The tps has two connectors one for the engine control and one for the transmission. Remember the tps is basically a potensiometer. Think of it as the volume control on an old radio, you get bad sound, cracking noises.

Torfinn

its an 89 4.0 also on the side orig tranny with around 180 on it

i am not familiar with the tps....could someone tell me where it is and is it an easy fix for me to do?

TPS adjustment is easy to do, but hard to explain. Your gonna need an accurate digital volt meter (one that will measure to at least one decimal point or 1/10th of a volt accurately) and maybe an old style ohm meter with the analoge (needle type) pointer, which is used for one test.
Half of the TPS (outside) is for the transmission control unit and the other half is for the egine controller.
Search TPS adjustment, there has been a few posts that explain it much better than I can.
If your 02 sensor is probably bad, it will pay for itself pretty quick in gas savings. I just changed mine and am saving about $3-4 a tank. MY 02 sensor will pay for itself, in like three months, of driving.
I recently had a TPS, where the connector contacts were oil coated, it was shifting into the same gear at different speeds, kind of erratically.
I had one TPS that had a hitch or dead spot in it, (in the motor controller half) which was at about 1/3rd throttle opening. If I accelrated quickly I wouldn´t even notice, if I accelrated slowly and/or was cruising at exactly the right speed, the motor would kind of loose some umph, kind of hestitate.