Rough Shifting Transmission

I have a 1999 buick Regal - 63K miles in excellent shape overall. In the past month I have been experiencing an intermittent(while driving) hard shifting. Usually, the tranny has been very smooth.

Once I turn the car off all is well, until the next time which has yet to be predictable.

Any assitance would be greatly appreciated. Am I in for some trouble or a reasonable fix?

Thanks,

Scott

You should take a look at this thread in the Century section.

http://www.automotiveforums.com/vbulletin/showthread.php?t=179354

Have you checked the transmission fluid lately?

I have a 1999 buick Regal - 63K miles in excellent shape overall. In the past month I have been experiencing an intermittent(while driving) hard shifting. Usually, the tranny has been very smooth.

Once I turn the car off all is well, until the next time which has yet to be predictable.

Any assitance would be greatly appreciated. Am I in for some trouble or a reasonable fix?

Thanks,

Scott


Scott,
I have a 1999 Buick Regal with the same problem. I have been doing some investigating and have found out that this is not unusual for Buick Regals of this time period. There is an earlier thread from a 2000 Buick Regal owner that is having the same problem.

Our hard shifting problem is also intermittant. I checked the fluid level and it was fine. We have had it to a transmission shop and they couldn't find anything wrong.
I intend to check all of the electrical connectors on the transmission as this is what it sounds like to me. I'm an Electronic Engineer and I've seen this type of problem happen on other mechanical/electronic equipment. I'm almost thinking that there is a major design problem here that GM isn't addressing.

Scott,
I have a 1999 Buick Regal with the same problem. I have been doing some investigating and have found out that this is not unusual for Buick Regals of this time period. There is an earlier thread from a 2000 Buick Regal owner that is having the same problem.

Our hard shifting problem is also intermittant. I checked the fluid level and it was fine. We have had it to a transmission shop and they couldn't find anything wrong.
I intend to check all of the electrical connectors on the transmission as this is what it sounds like to me. I'm an Electronic Engineer and I've seen this type of problem happen on other mechanical/electronic equipment. I'm almost thinking that there is a major design problem here that GM isn't addressing.

The problem with the intermittent rough shifting is not limited to 1999 Regals. However, I had the same problem with my '99 LS. I've seen and heard of model years 1997 - 2003 acting up on the 4T65-E and 4T65-E HD trannies. I believe that there is a GM TSB out for 2001 models where they recommend disconnecting and re-connecting the 20 way cable going to the tranny from the ECM/PCM. The connector is the big gray electrical plug on the driver's side above the tranny side cover.

To this day I really don't know what corrected the problem which included a whining sound in addition to rough 1-2, 2-3, 3-4 upshifts only. No DTC codes set. BTW - It wasn't the PCS (Pressure Control) solenoid/valve.

I have a 1999 buick Regal - 63K miles in excellent shape overall. In the past month I have been experiencing an intermittent(while driving) hard shifting. Usually, the tranny has been very smooth.

Once I turn the car off all is well, until the next time which has yet to be predictable.

Any assitance would be greatly appreciated. Am I in for some trouble or a reasonable fix?

Thanks,

Scott

Have you change the transmission fluid and filter? If you have over 63k mile on the car, with the same fluid, the transmission fluid might be broken down, and not working properly... I have a 1990 Buick Regal, and I recently had my transmission fluid change, and it made a big difference on how the transmission progresses to the next gear. There use to me a slight hesitation going into the next gear, now it progresses smoothly with no hesitation.


Ajscottjr

I finally figured out our problem with the intermittant shifting transmission. It was a poorly gapped spark plug. At 89000 miles I decided to do a spark plug change. Five plugs were gappped at .060" One plug was gapped at .069". It looked awful. I replaced all of the plugs and the problem has gone away. No more jerky transmission shifting. I would have never guessed that a bad spark plug could cause this type of problem. What gets me is that the Buick dealer couldn't have figured this out.

Harpoon5.2

I finally figured out our problem with the intermittant shifting transmission. It was a poorly gapped spark plug. At 89000 miles I decided to do a spark plug change. Five plugs were gappped at .060" One plug was gapped at .069". It looked awful. I replaced all of the plugs and the problem has gone away. No more jerky transmission shifting. I would have never guessed that a bad spark plug could cause this type of problem. What gets me is that the Buick dealer couldn't have figured this out.

Harpoon5.2

Thanks for the feedback. What about 1 1/2 years later? The thread is now too old so I'll have to close it.