First time here. Great site.
I have a 97 SE 89K miles. The last couple of summers I have noticed a little surging when I hit hills at cruising speed. Someone described it like having a fish take your bate. Deallership did diagnostic. Had me change plugs/wires and I also replaced one coil. It doesn't seem to be electrical. I am convinced it is the locking torque converter slipping or disengaging and reengaging. The RPMs jump 300 to 400 and back constantly on hills. THe AC on or off has no effect. I was told I could disable the locking converter, but they couldn't tell me which pin to pull on the trany wire haness.
Changed the trany fluid. This seemed to help for a couple thousand miles, but then it came back. Any Ideas??

I would greatly appreciate any input.

Todd

Welcome to the forum, twilks! I'm sure we can get you in the right direction on this forum. My first thought was the wires/plugs, but since you all ready replaced them, I'm at a loss. You will have to check to see if your bonneville is throwing codes. This will tell you what to focus on.

If you are unsure of the code meanings, the Rat and Wilwren will be able to decifer them for you.

Good luck, and welcome again!

And jrs3800, speedguy, deathrat, or 99bonnevilleSE will be the best tranny guys if it goes that direction......Get us some codes. Makes it easy.

Someone had the same problem with the locking torque converter. If you search the forums, you will find the thread. Or DeathRat might be able to point you in the right direction.

The 2 most common problems are the TCC Solinoid & the Valve Body Gaskets! Either way YOU'VE GOT TO PULL SOME CODES HERE FOR US TO HELP YOU BETTER!

I am very impressed with this site and the instant replys. At the same time it makes a back yard mechanic feel ignorant. Regarding pulling codes, is this something the dealer has to do or is there a proceedure for reading blinking lights off the dash??
Please advise.

I agree! A mechanic did this on my father-in-laws GP. It wastes gas and was the 'cheaper alternative' than the repair. Our Bonnevilles were designed to run efficiently while giving us ample power. If you pull the pin, it will not be doing its job efficiently. In the long run, it will cost you more in gas than it would to just fix it properly.

Good luck.

Try your local Autozone store for a free code scan. If it comes up clean, it may be as simple as a mis adjusted or flaky brake pedal switch. This switch on the brake pedal cuts off power to the TCC when the brake pedal is applied, but it can be loose, bad or out of adjustment and the TCC will go on and off as the car shakes over bumps in the road. I experienced this on a 96 suburban which uses the same system on the TCC. You can check it out easily by kicking the brake pedal while on the freeway at cruise speed, in OD and watching the tach. If it jumps up when you kick the pedal sideways, (not down) look further into it.
Good Luck

I have a 94SSE and been trying to find the same problem for four months. My transmission failed and I had it replaced by one from the junkyard. The 2K RPM surging problem is now gone. To me it seems that the problem was the tranny. I had no fault codes just the problem.

Good Luck
Joe

Remember our transaxles are very picky about fluid levels and on top of that they were built to only last so long. The stock performance capability of the 4t60-e and 4t65-e are both slim to non. So then add years being driven by a dad or granddad and then thrown to a young driver. The problems that come up are normal. Now there are options that can lead you to a performance transaxle that will take abuse on a regular bases with alot less problems. I know that a new intense or ASG transaxle is not cheap but in the end either is swapping in new yard transaxles every 2 years. So if you can save for a performance transaxle you will not have to worry about it unless you decide to bolt a 500hp engine to it. I know the plight of the average Bonneville owner is repair after repair but this site covers every repair solution there is and in the end it comes down to buying quality replacements or properly managed units. If you buy a stock transaxle you will want a big transaxle cooler you will want a shift kit (4t60-e kit coming) and you will want to change fluid often and if you can handle a bit more cash a limited slip will help alot too. Those are the options. If this is confusing or you need help either e-mail me or you can find my phone number on my site.

Ty