When I am accelerating in the Bonny my engine is shuddering. I leave it parked in the garage all week. When I got it out Friday night to drive it around I had no problems. Then on Sat. I was driveing it and it started to shudder. I have 42k on it now. I thought it may be bad gas from sitting all week so I put in some water remover and injector cleaner. Filled up with premiuum like always with no change. Any ideas would be grealty appreciated. Oh yea and no check engine light. :(

Between what speeds do you notice the shudder? I'm not sure if this relates to your particular problem, but we had a discussion not to long ago about Torque Converter Shudder.

http://www.bonnevilleclub.com/forum/...pic.php?t=5086

I'm sure the Guru'* here will be able to help you diagnose your prob.

If it is torque converter lock-up , I had the same thing. My husband and I bought the car (same as yours) last summer, and while it was under warranty had every little thing fixed. One of the things that bugged us was the shudder. It was very slight, but we felt it when going between 45-60mph uphill (the bigger the hill, the bigger the shudder). However, if we pressed the accelerator or let off a lot, it would go away.

We were told that it was because the tranny needed to be flushed , so they did and it didn't help a bit. We brought it back and they took it for a longer drive and determined that it was the TC, and they replaced it. A few days later we brought it back because it was still there (though not as bad) and they ended up replacing the software with either an update or the 2001 Bonnie software (not sure, they never really explained it). That completely took care of it. The mechanic said that it was a flaw in the 2000 design and that Pontiac was well aware of it at this point, but that since it causes no damage, they don't worry about it unless someone wants it fixed.

He might have just been blowing smoke up our , but I hope this helps a little.

It happens at all speeds especially at between 35 to 45 with the O/D on while under a load like going up a hill. It also happens the whole time I am accelerating. If I put it to the floor it will shudder the whole time untill I level it off and just maintain speed. I am not sure what to make of it. I am taking it in tomorrow to have it looked at. It acts and sounds like an engine that is backfiring through the intake manifold. I know that is not the case.

I had a similar problem (transmission shudder) while climbing long gradual hills at speeds of approximately 65-70mph. I took the service advisor from dealership up onto I-95 (I figured the thing wouldn't shudder because I'm trying to demonstrate it to the advisor, but it did shudder), he ran diagnostic on the transmission and I think he was able to take control of certain functions with the lock up. Anyway long story short, they replaced what they refer to as a valve body in the transmission. This resolved the shudder problem. markwb

I took it in for service, and they diagnosed that it was a corroded coil and corroded plug wires. Which I am kind of embarrassed about. It is my understanding that these cars are not supposed to need a tuneup for 100k. I dont agree with that anyway, I was planning on replacing the wires and plugs with HIPO units later on. I just assummed that they were good because the car idles fine, and at 42k they should at least be good. Anyway that is the problem I have yet to test it because. have not replaced the coils, wires, and plugs yet. I purchased a Hi performance coil pack from Jegs, and I plan on getting some Accel wires. with the Iridium plugs.

I would not waste any money on high performance coil packs. The stock coil packs work great, and high performance ones make little or no difference at all. Go down to the autoparts store and pick up all 3 of the coils, they should be pretty cheap, don't waste your money on the high performance crap. The fact that the fastest Grand Prix guys run stock coils may make your decision a little easier. (They all run 11'*)

It does not suprise me at all that the coils and wires are corroded, and since that is the case good luck getting them off. The stock wires are very difficult to get off with only 42 miles on the car, let alone 42,000 miles, and in many cases I have had the stock wires break apart while trying to get them removed. (2 of them broke on our '00 SSEi)