Anytime I set my cruise control, the RPM's bounce up and down. It seems like the motor doesn't know which gear it wants to be in.

So far, I have replaced the TPS, cleaned the MAF, PCV Valve is fine.

This issue also presents itself when I'm cruising about 50mph and my foot is barely on the gas (just trying to keep speed).

This is really irritating - any help is appreciated!!

 

Iv had a prob similar to yours. Came to find out it was my crankshaft position sensor. It has a crack all the way through. If its the same you would need to get the relearn process done. Hope that helps and good luck

 

Might also be the torque converter locking and unlocking. Are you sure its only doing this in cruise control? When i had this problem, it was worse in cruise...guess it was more sensitive with throttle control.

 

Sorry, I must have left that part out - it seems to be exacerbated with the cruise control, but regularly occurs when driving down the highway.

At 60mph with my foot barely on the gas, just to keep speed, it sounds & looks like the tranny has trouble deciding which gear to be in.

It is at this point that the cruise also gives trouble, leading me to believe that it likely has nothing to do with the CC module.

The CEL is also not illuminated. (could it still give a code without the CEL on?)

 

Prolly want to start with the TCC solenoid. Search around here...there are posts. I think you only have to drop the tranny pan to access.

 

dropping the tranny pan - does that require more than just draining & removing the pan bolts?

 

I'm not even sure if this makes sense; hopefully one of you experts can weigh-in.

I've continued having the lock-up issue. There are a few gas stations here in town that sell "100% gas" (from what I understand, they can still have a small amount of ethanol and call it 100% gas). Anyway, in an effort to see if I could get better MPG, I decided to give it a shot. $58.00 and a full tank later, I've been driving for about 40 miles and noticed the lock-up issue appears to have gone away and the tranny shifts normally.

Does this even make sense?? Is there any way the quality of fuel would affect the lock-up mechanism???

 

I know the original op was back in Feb but If your having fluctuations in the tach when driving at normal speed, check to make sure your trans is full of fluid. Trans low on fluid ack's as if the motor needs a tune up.

 

Great new ladies & gents.

it appears my issue has been fixed and here's what I did:

At the same time as my "lock-up" issue, I was having issues with my shift indicator & mileage lights flickering. This past weekend, thanks to another post on here, I took apart my instrument cluster and re-soldered the ground points on each of the display mechanisms.

Low and behold, the flickering has stopped and to my pleasant surprise, the shifting issue has been resolved!

I took it to the local (reputable) transmission shop for an evaluation and he just called to tell me that his tech had driven it 5 times without being able to reproduce the issue. I told him about my recent repair and he indicated that they very well could be related since "just about everything grounds through the instrument cluster".

I thought you all would like to know...

Does anyone think these are not related and merely a coincidence?

 

Oops, forgot to mention this very important part: They added 1 quart of tranny fluid - it was low....