8th Dec 2008, 16:33

I`m also curious with the same questions directed toward the Nov. 24th posting.

I suspect there`s a lot more going on than just with the computer.

Too many people have had transmission flushes and fluid filter changes at the proper level with no change in performance. It was only when the solenoid was change out that it made a difference. Even though GM`s defective solenoid was used, it did at least temporarily solve the problem.

I am more inclined to believe that the Trans Tune product by Seafoam most likely corrected the problem by cleaning out any sediments, putting less stress on the solenoid.

If you`ve first tried to correct the problem by bringing the fluid level up, with also removing the battery cables for 5 minutes or more to reset the computer, without using the Trans Tune, I might agree that the computer is too sensitive.

The fact that you have to use the Trans Tune treatment still, leads me to believe that it is a solenoid problem. The higher the temperature, the more that the solenoid is affected, especially if the fluid is low.

Would like to read anybody`s comments if they`ve tried this procedure without the Trans Tune treatment. If so, it looks like a cheaper fix.

13th Dec 2008, 12:21

I've got an Impala (3.4 unfortunately) with 160k on it, and now it too has set the P1811 code. The tranny was flushed a while back and was working OK. I added a can of GM transmission seal conditioner (p/n 88861315 in Canada) and so far so good.

22nd Dec 2008, 19:34

I have a 2000 Park Ave with 40,000 miles on with the same problems, and was also curious if anyone else has tried the trans tune by sea foam & dis-connected the battery with any success? And if so, how long did it last?

28th Dec 2008, 10:16

I tried the unhook the battery & use 1/2 can of Seafoam on my 1987 Park Avenue, & have put 200 miles on it since, & so far no problems yet.

29th Dec 2008, 11:48

Well I talked to soon - it's just a temperary fix - has started doing the same thing again.

20th Jan 2009, 22:34

I have a 2004 Pontiac Grand Prix GT2, and at about 80k I experienced the same issues. Code 1811 Maximum Adapt and Long Shift.

I took the car to a transmission shop and had the transmission specs. checked out. Results: The PCM recorded that the code was set three times in one driving cycle while I was driving at the speeds of 10 to 15 miles per hour. Now that is consistent with my issue. The code is triggered by slow take off, extended loss of traction and overloading the car.

Example: if you're taking off slow and the car is trying to get to second gear, then you slow down or speed up, the PCM extends the shift time because of the slow take off. The way to repair this issue is to trick the PCM into thinking the car is shifting sooner. ZZperformance has a shift kit that you can place in the accumulator’s 1 and 2, which is assessable from the transmission pan. It is also a good idea to install the cooling pan that was designed for the 4t65e transmission.

Also, upon research and self lab testing, the OEM filter in the 4t65e transmission has a much much thicker pad in the filter, which allows more filtration and better shifting vs. the after market filter, which is very thin and allows passage of varnish and trash, which becomes lodged or clogs the PCS.

PS because my car is much newer than most, I have contacted GM and they are willing to repair this issue if your car meets the qualifications. But they are still yet producing cars with this issue.

3rd Mar 2009, 07:04

Except this winter, I have driven this faulty transmission for several winters. I live in Winnipeg and our winter is consistently cold. I have noticed that it never does the jerking when its very cold. As soon as the temp starts to warm up to about -5 celcius and above, it starts to jerk as it shifts. Just a thought, is there a way we can keep the transmission cool? Maybe it might make us happier drivers.

18th Mar 2009, 23:59

I am an old man & baby the throttle, & it makes no difference. When it gets hot, it slam shifts. 2000 Buick -- It has been doing it for 3 years!

19th Mar 2009, 11:54

I too have had the hard shifting problems previously noted by many others. Have 61,000 miles on my 2000 Buick Century. Problem is intermittent and goes away after the car sits for a while. Had the transmission fluid changed but it made no difference. Guess I'll just put up with this problem rather than spend a bundle for a repair at a dealer, with no guarantee that the same problem will not come back again.

21st Apr 2009, 17:07

I am amazed - I just typed 2000 Buick problems trying to find out what is wrong with my car - I have read all the entries and hard shifting is exactly what I have, and yes it is true, shut off the car and it resets itself. So guess what I am reading is true - guess it is something I need to live with until I get rid of my car. Thanks so much to everyone who has made entries, and sorry you are having the same problems as I am.

2nd May 2009, 02:15

I purchased a 2001 Buick Century last Tuesday from a dealer in Cincinnati. The vehicle has 125k miles on it.

On the second day of ownership, I noticed that after driving it for 60 miles, the transmission would hard-shift when taking off from a stop. If I parked the car for a few minutes and then continued driving it, the problem would go away. I will certainly not pay $600+ to have the problem corrected.

The car also has the SES light on the dash.. I wonder if this problem is setting off the light? The only other problem that I have with the car is a broken fuel gauge. As long as I use the trip-odometer I'm fine.

This is a very nice, comfortable car and I absolutely enjoy driving it. It is a shame that GM will not recall this issue, but given the financial problems they are going through and the economy, it will probably never happen.

Anyway, I will try the SeaFoam "cure" and see if that helps at all. Thanks.

7th May 2009, 15:20

2000 Century. Would shift harshly thru the gears. I took it to the Buick dealer and he knew immediately that it was the pressure control solenoid. A fairly cheap part, but the trans had to be dropped to get to the plate which the solenoid was behind. A mainly labor intensive job, especially at a dealer. Try stopping the car, turn off the ignition and wait a minute. Then start the car and drive. Usually this solves the problem for a while. I have been able to go 200 miles before it showed up again. I have had it replaced at 60,000 miles. 100,000 miles later it has shown up again. Same problem, same fix. I am going to a local shop for their estimate.