Tranny Slipping in OD

98 Cherokee - 4.0 L - 4 sp Auto

My check engine light came on last week, at the same time the tranny started slipping when starting from a dead stop in 4th (OD). I have changed the fluid and filter, but there is no improvement. The old fluid was quite dark, even though I had the tranny flushed only 3000 miles ago. When I shift manually from 1st to 4th there is no problem. Any ideas?

First, I would find out what the code was, even if the "check engine" goes out, there is still a code. IF your tranny worked well, manually shifting then I would look possibly at your TPS sensor, this one sensor can raise all kinds of problems with shifting.
When you had it flushed, did they change the filter, and what fluid did they use? Was there a particular reason why you had it flushed? Mileage?

By all means download your trouble codes. The Throttle Position Sensor (TPS) can cause some grief with the tranny shifting. Also ...the Throttle Valve Cable (TV cable) could be out of adjustment ...the TV cable adjusts the internal operating pressures of the tranny based on how much you're mashing the go pedal ....an indication of load on the engine ...the harder you push, the higher the presures need to be for proper shifting. This cable is *not* a kickdown cable like you'd find on older automatic trannies. If the TV cable is not "synched" correctly to the throttle, you won't get the needed increase in operating pressures and the tranny can begin to slip ...keep it this way for a long period of time and you'll trash the tranny. To adjust the cable: push down on the locking tab with a screwdriver and pull the cable fully back toward the the engine. Release the tab. Next, you can either sit in the drivers seat and floor the accelerator or manually operate the throttle at the throttle body to the full open position. As you open the throttle fully (either method), the TV cable will ratchet out through the adjuster and set when the throttle reachs fully open. That's it ...end of proceedure. Give this a try and see if it helps any.....these are the "cheap" fixes ...after this you're looking at maybe the tranny computer or possibly the transmission itself having internal failures.

Mike
00XJ