hey everyone

i think for once i have a real problem. Took the bonnie over to get oil change and had the guy look at the engine. My mounts are perfectly fine, however he says i need to visit a transmission shop. The hard shifting is due to an Pressure control selenoid, and i searched that info on the sticky on BC and sure enough the symptoms are accurate.

Problem is ive been driving it like that for say 7 to 8000 miles because we figured it was the mounts for a long time. is it a simple $580 fix like the sticky says, or is my tranny due for some major TLC??

I'd say take it to a tranny shop just to be sure. The thing they don't tell you is that a PCS failure feels JUST like a tranny with bad fluid. I thought it was going on with the Impy, but I flushed it, and the symptoms went away. Have them look at it and see what'* up.

yeah it is headed there, however i think the tranny fluid is ruled out. it has probably 9000 miles on the new fluid. it was flushed a few months ago with a new radiator.

thanks!!!

I've been dealing with the same thing for about 5k miles. The first thing I did was change fluid. That helped for a while. Then I changed fluid and added Sea Foam Trans Tune. Again, it helped for a while. The way I changed the fluid was to suck it out the dipstick tube, so I only got about half of it.

What I understand, is that the Pressure Control Solenoid can get sticky due to the fine debris that comes off the clutches as they wear. This is apparently why changing the fluid worked for a while. Since I didn't change the filter, the new fluid probably didn't stay clean for long.

Yes, but was the filter changed too? After my experience, I wouldn't jump to that conclusion.



I looked at the Transgo Shift Kit on eBay and they claim to fix this problem with their kit. I ended up with the Thrasher Kit (which should be very similar) and installed it yesterday (along with the filter it came with). I will bet LOTS of bucks that my PCS symptoms are gone for GOOD! :o The cost is $90 plus fluid.

From what I have learned, the sticky PCS causes the clutches to slip too much. The PCM notices this and goes into a protection mode (excessive clutch slippage causes excessive wear). This protection mode is to shift hard as to not allow for excessive slippage.

The Shift Kit tightens up the shifts so there is a lot less slippage. The experience of driving the car is overall more solid. Even if your trans was fine, I would say add the shift kit because it makes such a huge difference in the feel of driving the car.

See my post:

http://www.bonnevilleclub.com/forum/...ic.php?t=80707

Another option to try, is to have your PCM re-flashed with an update. I visited a tranny shop a month ago and they said there is an update that supposedly addresses this issue. They quoted me $145. I haven't heard if it really works though.

If you ever experience the intermitten hard shift problem it is recommended that you get the tranny serviced ASAP (the pressure control selannoid which I haven't replaced yet) however in the interim I have found that if you pull over and turn off the car for as little as 20-30 seconds and restart the hard shift problem goes away.

For me the hard shift is a very intermitten problem which apears to coincide with an above average engine tempurature, on particularily hot days or when I have driven it hard for a while.

This can work because the hard shift is caused by the PCM commanding minimal slippage as a precaution, after it senses excessive slippage. Shutting down and restarting, essentially re-boots the PCM and can reset the commanded minimal slippage shift.

Apparently, the Pressure Control Solenoid is used to regulate the fluid pressure that controls the clutch engagement. With age, the fluid builds up a fine contaminate from the wear of the clutches and this can cause the solenoid to be sticky (for lack of a better term). This can then cause the clutch engagement to be less than ideal and the PCM will detect it.

My experience was that, as the transmission reached the upper end of its normal operating temperature, the effectiveness of the fluid was slightly reduced and the problem occurred.

It seems the Shift Kit takes away the critical nature of the slushy shift that GM intended, and therefore relieves the burden on the solenoid. There is a world of difference in shift quality after the shift kit.

whos ready for what happened today???

2 mechanics have looked at my car. It had 2 problems.
1.Hard Shifting 2. Constant vibration when driving down the road, even on cruise control.

The engine as expected is fine. as it should be, its a 3800 series. As for the transmission (if anyone wants to tell me the tranny name that attaches to the L36 it would be appreciated) as for the tranny, its filter was changed and new fluid was put in. This was NOT a flush, thats the worst thing to do to a trans, i learned that with the 1992 about 3 years ago.
So now it shifts perfect, its amazing what a filter and some fluid can do.

The vibration is due to something in the wheels..either the hub or the bearing. Thats on the laundry list for next week.
I am keeping the 2001 Bonneville after all of this. 1. Its half way paid off.... 2. I took it to GM today and they offered me 4500, and another GM dealer said 4400 dollars. And when it was pulled away both times, it hit me that ive got a nice car, just maintain it.

Anyone have any good forum links for discussion on wheel hubs and bearings. im gonna look and see when i get time. I think ive repaired every part of the car, lets hope one day its done.

It'* a "4T65e"

Keep in mind that when you change fluid, you only change about 60% of it. So you still have 40% of the old stuff. I would drive for 1k miles and change it again, that way you have about 85% new fluid. Also, it may be that your harsh shifting will return shortly (as mine did). If it does, I recommend the shift kit for $100 - $110 instead of the Pressure Control Solenoid for $580 or more.

Have you checked the wheel balance? A bad bearing will likely make a LOT of noise before it sets off a vibration.

brand new tires...im sure the wheels are balanced. its been doing it before the new tires too.

as far as the fluids concerned...it had a radiator leak for the transmission line and i probably pourned a few quarts into that transmission until it was fixed. ill look into the shift kit.

You said you've repaired nearly every part and yet you still think it'* a nice car? Agreed they look great and have a great engine. That'* it. Mine has part after part go. Still sitting with blown tranny. Bad shocks, Wheel speed sensor/hub gone, noises/vibrations. Eletrical problem with no power to 3 doors, leaky trunk. The list goes on. They are cosmetically a price of crap and have been very half assed designed. It is by far the worst pontiac I have ever owned and the worst car in general. This is GM'* Road version of a 26 ft boat. A money pit, beleive me. Had a trans-am for 10 years. Spent a total of $2K on it in that time. Had a Sunfire for 9 year. Spent $956 in that time. Had this for 16 mo and have a total of about 4K so far with another 9K still owing on the loan. You might want to consider the $4500 fast