I've been having this problem since the end of the summer. Had my tranny 4L60E tranny rebuilt in May and it worked fine all summer. End of summer i would start to get hesitation in the RPM's right after it shifted into 4th gear when cruisin, like going into 35mph or 45-45mph. Revs bounce up and down for a sec or two. It would only noticeably do this when the car was warm.

Tranny place fixed the tourque converter and the leak and said it should fix it, it didnt. They couldn't really pinpoint it. THey say now that PCM needs to be flashed or its a hangin valve in the tranny.
I havent been back to them because I have been busy, but they were going to take the tranny out and check the valve to see if it's the culprit.

Now, i guess since its almost winter it doesn't do that exact thing anymore. When it shifts into 4th now, it takes a sec to drop to the lowest REV. Drops to 1700 then to 1500 when it should drop straight to 1500.

Just wanted to let you guys all know the specifics of my problem. If any knowledable tranny guys are reading, lemme know if a hanging valve in the tranny sounds right or if its the PCM or something else.

 

Sounds like the torque converter clutch is coming on after the 3-4 shift, that is what is supposed to happen. What is yours doing that is different?

 

Well, i don't know too much about how torque converters work, but when i said before that they fixed it, they told me that they recalibrated it.
Also its just what i was saying, the split second after it would shift into 4th gear (i guess overdrive gear) it would start slipping. Revs would bounce up and down and the car would not have any real pick up. The car was fine for about 3 months after the rebuild. Its just a stock 4L60E tranny.
I don't know what else to say, that's why i am askkin for help.

 

It might be the torque converter clutch. Try touching the brake pedal when this happens and see what are the changes if any?

 

I'll try that and watch closely, i have to wait for the car to warm up. From what i can remember though i think if i hit the brakes during it, the bouncing just stops and the car slows down like normal.

 

The car just slows down like normal...i didn't notice anything.

I feel this hesitation most when i'm going up hill, feels like car is just stumbling when its in low 4th gear. Feel like i'm not going anywhere.