I need some expert help to figure out what is happening. I have a '01 SSEI with nearly 100,000 miles on it, mostly highway, and just in the last couple hundred miles, the shifting between gears is real abrupt. It only seem to happen when the car is fully warmed up and driven for a while. If I stop and turn off the car, and then come back just 5 minutes and start driving, i can hear the tranny whine with the engine, and it shifts hard between gears. Every gear feels about the same, but fourth feels the worst. Manually downshifting is scarry. I have taken it to the dealer, and they found no codes, no wear. They flushed the whole system, and replaced filter. The even cleared the ECM, as they though there was something corrupt, and reloaded some profile into the ECM. It works fine first thing in the morning, heading in to work, but slow down, stop at a few light, and then it will starts. The dealer said to give it two weeks to relearn our driving habits, but this whining does not sound good. Any Ideas? Fluid pressure? Fluid pump? I'm already out of $350.

Thanks.

I'm assuming your out of warranty? When you say they found no wear are they talking about anything in the tranny pan? No shavings or anything on the magnet? How was the fluid? You say you have 100k on it, did you get regular filter changes and flushes at the proper intervals?

You mention the down shifting as 'scary', does this mean the engine is braking the car but it sounds rough?
When it shifts hard is this during acceleration or steady throttle posistion?
With your milage and the service men not able to locate it try this.
Perform a stall test to make sure the noise is actually coming from the converter:
Place your foot on the brake.
Put the gear selector in DRIVE.
Depress the accelerator to approximately 1,200 RPM for no more than six seconds.
A torque converter noise will increase under this load.
If there is no diff in sound then I would suspect the Control Valve Assembley?

I have had two fluid changes. First was around 40,000, and this one at 98000. We drive alot of highway miles, and believe the 20-30k mark is a little excessive. My '90 Bonnie LE has almost 400,000 miles, stock tranny. Changes are at 50,000 and never had a problem.

There was no metal shaving in the pan, according to the tech. The noise follows the engine RPMs, at least when it in neutral, but I sure its also in park, and it only starts when it engine is at 195f, and has been sitting, running. If I were to drive my usual 50 miles to work, the tranny will shift perfectly smooth the whole way, speed changes don't affect it, like slowing down for traffic, and then speeding back up. But sit idling for a while, like a couple of minutes, and the noise will appear and the gears start connecting hard, not slipping, just not smooth.

The sound is kinda of like the sound the SC makes when it winding up.

There was a note in the service manual about excessive miles and the linning of the torque convertor breaking down causing slipage and harsh (rapid) shifts. That is why I asked for the tc test. It also could be a contaminated control assembley but with a recent flush that should be ok?
I would take it to a tranmission shop and have them go over it. It may be something simple like an o-ring on one of the servos but with no codes and erratic operation they may not find anything the same as the tech.
Keep us informed as this is becoming a more common issue around here?

Thanks for the advice. The Torque converter sound very likely, especially with the conditions that seem to promote the problem. So, it could be like debrid floating around inside of the TC, it has insulation? I listened to the engine during the test you requsted, but it hard to hear without a load on the tranny, and going down the road. It has a harmonic, higher then normal pitch, usuallly noticeable at 20-30 mph, or 2-3k. In fourth gear (45mph), quiet, after a fast hard shift.

My wife was driving it today, over 100 miles and it was smooth all day. She stopped by the house to pick me up for dinner, and in 10-15 minutes it was sitting off, in the yard, when we left the house, it again was changing gears fast and hard. Maybe its me in the car. But, it calmed down after traveling at highway speeds (50-60).

Was this info in a service notice, like a SB, as I would like to have the dealer tech look into it. I say dealer as I already has spent the money, and they should have looked into this if its was a possibility.

I realize that I may be ahead in mileage to a lot of folks with '01 bonnies, and this could be a good heads up for those that reach this mileage. Will be glad to gave the gory details when I can get it looked at again. Everything mentioned so far has been very helpful. You guys are great.

Hey. I just wanted to let you know you're not alone. I have an '01 SE that just turned over 109K. It is doing the exact same intermittent shifting as your SSEi. It only happens after the car is warmed up, and some days it drives perfectly. Up until yesterday, it has not thrown any error codes, but finally did throw the SES light on while on my way home. I'm having the codes read tomorrow. Another problem which may or may not be related is the car stalling. I could be driving along and all of a sudden nothing. No power steering, power brakes, nothing. I get the car pulled over and it takes a few tries to get restarted, but eventually starts and I'm on my way. Also in some instances, the engine has not shut off but the tachometer all of a sudden reads zero. Its been to the shop many times with nothing to show for it but an empty wallet. If you figure out your shifting problem let me know. Thanks.

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Thanks,
Tracy