Mike Williamson

A few weeks ago I was driving down the highway at around 70mph, and the car shuddered. I actually thought I’d run over something in the road, but there was nothing there. A few minutes later, it happened again, coming out of a speed zone. In the next speed zone, while slowing down, I noticed the car slowing down more quickly than normal, as if I were in a lower gear. I then realized the engine rpm was about 1k higher than normal. Pushing the Overdrive button had no effect on anything. I pulled over and shifted into Park and then back to Drive. When starting out, it felt like I had no power, almost as if the transmission were slipping, but the engine wasn’t revving high like it should when slipping. I parked the car upon arrival at our destination, and then test drove it a bit later, and it was fine, and pressing the OD button had a normal effect on the engine/tranny. On the drive home, it shuddered again, twice, in quick succession, but drove fine the rest of the way home, just at higher rpm (3200rpm at 70mph, or 2700 at 60). Over the course of the following few weeks, it happened intermittently, and nothing environmental seems to affect it. It happens when it is cool, when it is hot, when it is dry, and when it is wet. Sometimes it will happen when I’m driving down the road, and sometimes it will happen from a dead start, without the shuddering. It seems as though I’ve lost the highest gear or two. Sometimes it will only shudder once, and the engine rpm is then higher, but not as high as when it shudders twice. I have found that when it happens, I can pull over immediately, shift to park, turn the car off, start it again immediately, and it is fine. This seems to indicate to me that it is something electronic that is not allowing the transmission to shift properly, or causes it to lose its ability to remain in the highest gear or two. Of course, I’ve checked the fluid and it is fine, not burnt smelling, and filled to the proper level.
Any suggestions? I’ve already talked to one shop, and they didn’t seem to know exactly what it could be, but immediately went to the option of replacing the tranny…something I’d like to avoid if this can be fixed by replacing a part. I’ve done a little reading, and one possibility seems to be the Governor Pressure Sensor. Another possibility might be the TCM?

ol"blue

Welcome to CF. Since purchasing our '04 GC new, we had to take it in under warranty twice to have the TCM "reflashed" because of shifting issues, and issues with overdrive not engaging. Everything has been fine since then. Even though you say the fluid doesn't look/smell burnt, it could still be a good idea to change the fluid and filter, just don't do a flush. When they do a flush, small particles can be flushed through the trans and can block the small passages, causing issues or damage later. Plus, many times the filter isn't changed when doing a flush. Our '04 WJ now has 112,000+ miles on it, and we've changed the trans fluid & filter twice since new. Cheap insurance.
WJ transmission service & maintenance. >->http://www.wjjeeps.com/service/transmission.htm