1999 Regal GS Transmission trouble

I grew up in a Buick family and love my 99 Regal....however, lately it's been giving me problems. The first thought was clogged fuel injectors because of a slight "chugging" at intermittent times. But now the car seems to shift harder than it used to and it "chugs" when it shifts into 3rd gear.

The transmission has never been serviced (shame on me) so I am taking it in tomorrow for that - but I wondered what you guys thought about what the problem is and what I should do. Suggestions?

The car has 91K miles and is in good condition otherwise. The only other problems I have had has been with the supercharger.

I grew up in a Buick family and love my 99 Regal....however, lately it's been giving me problems. The first thought was clogged fuel injectors because of a slight "chugging" at intermittent times. But now the car seems to shift harder than it used to and it "chugs" when it shifts into 3rd gear.

The transmission has never been serviced (shame on me) so I am taking it in tomorrow for that - but I wondered what you guys thought about what the problem is and what I should do. Suggestions?

The car has 91K miles and is in good condition otherwise. The only other problems I have had has been with the supercharger.

Do you ever get a SES light? I'd start with the basics such as spark plugs, wires, pcv valve, air and fuel filter. The 4T65E-HD tranny is sensitive to engine conditions such as misfire, etc.

With 91K miles it wouldn't hurt to run some fuel injector cleaner through the system like Lucas and get the ATF and screen filter service done.

Is your CAT convertor the original?







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No, the SES light never appeared.

Checked the plugs, wires - they're fine. PCV valve, air and fuel filters have all been changed recently. The injectors have been cleaned too.

I had the transmission serviced and filter changed this morning - I'm curious to see if this makes a difference. Fluid was clean, no metal.

The CAT convertor is the original.....

Thanks for responding - I've exhausted all the things I know to do.

4T65E's are notorious for hard shifting problems.

Do a search on "4T65E harsh shift"

OK, I researched what you suggested and that is exactly what my car is doing. Here's the problem, I am not knowledgable enough to know how to complete any type of mechanical repairs and the mechanic I normally take this too looks at me like I am from another planet. Aside from taking the information I found and insulting him, I don't know how else to explain it.

If this is truly the problem (and it sounds 100% like it) I feel like I've wasted the $$ I've spent on other maintenance.

If this is a trans problem, a trans capable scanner will pick up a code such as 1811, or 1870, which are solenoid and/or valve body problems.

I guess im a little too late but i was going to suggest not to have trans. flushed...i hope they just dropped pan and replaced filter and fluid...Like suggested, you need to have it scanned...sometimes there will be no SES light.... Maybe it is kicking into 4th gear too soon

The harsh shifting occurs due to a line pressure problem (high) which is a typical and known problem on 4T65E and 4T65E-HD trannies. There is a high probability you have a sticky or defective (PCS) pressure control solenoid. P1811 long shift adapt errors have been addressed by GM Technical Service Bulletins for the past few years. Normally replacement of the PCS takes care of the problem but not always.

You have nothing to lose at this point and if you haven't done so try some tranny additive such as Lubegard, Sea Foam or Trans X. It may or may not cure the harsh shifting problem but then again you never know. These additives haved works for others that own Regal and Century and that includes me. Best $7.00 I ever spent on a car repair. Good luck!

BTW - Is your torque convertor locking & unlocking properly?

Thanks bnaylor for the suggestion on lubeguard - that seemed to make a difference for a while.

I still seem to be having trouble and the computer will not detect any problems. I did find that the wrong spark plugs were put on the car last time, so those have been changed.

I find one thing and then the car is ok for about a week, and right on schedule this morning when I let off the gas it gives a mild jerk, more than the normal change.

Any suggestions? I'm at my witts end.

Thanks bnaylor for the suggestion on lubeguard - that seemed to make a difference for a while.

I still seem to be having trouble and the computer will not detect any problems. I did find that the wrong spark plugs were put on the car last time, so those have been changed.

I find one thing and then the car is ok for about a week, and right on schedule this morning when I let off the gas it gives a mild jerk, more than the normal change.

Any suggestions? I'm at my witts end.

If the Lubegard made a difference for a while then it indicates that there are issues with certain solenoids and the valve body. It sounds like the TCC apply solenoid is acting up. That jerk could be the torque convertor clutch (TCC) locking and unlocking. The '99 version of the 4T65E tranny also uses a TCC-PWM solenoid to control the torque convertor in conjunction with the TCC apply solenoid. If it's solely due to high line pressure, it could be the pressure control solenoid (PCS).

It's more frustrating because you are not getting any tranny DTC codes. Most people that I worked with on similar problems wound up taking it to a tranny expert. Changing the solenoids out is not easy or typically DIY. The solenoids along with the valve body are located underneath the side cover assembly of the driver's side of the transmission and requires major disassembly/removal of parts to get at it. I'd have the PCS, TCC and TCC-PWM solenoids replaced. Good luck!






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Ok, I am going crazy. After two months of no shifting problems, it's back. I took it to the mechanic again today, again no codes, no problems with the torque converter locking/unlocking according to the trans. comp. Yet while nothing showed, my car has been doing this constantly since Tuesday morning, 1/10/06. It even did it on the way to the mechanic's this morning and on my way back to work this afternoon.

Does anyone have any other suggestions of what to try before I pay someone an insane amount to remove the transmission and check solenoids, etc.?

Could this have anything to do with power issues? I just don't know what else to do. Help, please. Thanks, I'm frustrated.

Someone who is familiar with diagnosing driveability and trans problems needs to drive this car under the fault conditions to feel what is happening, if it is a trans problem only a full function trans scanner in the hands of an experienced trans tech will reveal the problem.

Someone who is familiar with diagnosing driveability and trans problems needs to drive this car under the fault conditions to feel what is happening, if it is a trans problem only a full function trans scanner in the hands of an experienced trans tech will reveal the problem.

Earlier he mentioned the super charger as the only other problem, but no one said how they interact. Worth looking into.

Does anyone have any other suggestions of what to try before I pay someone an insane amount to remove the transmission and check solenoids, etc.?

The tranny does not have to be removed to replace any of the solenoids. In your case either the PCS, TCC and TCC-PWM solenoids are probably the cause. Labor should be around $500.00 and each solenoid runs around $50 each.

I've replaced solenoids in a 4T65E and it took about a day DIY. The solenoids and the valve body are located under the side cover located on the driver's side of the transmission.

It is not going to fix itself and will probably get worse once the weather warms up.

On my 91 Regal GS the shifting smoothed out and the hesitation/chug cleared up with a set of new wires, plugs(the correct ones) and what the hell new coils. All my choice. Per the mechanic, wire's showed signs of arching, plugs had very little nipple left to them. Shifts so well now I need to get the transmission mount replaced.

Just an update.....I had the PCS and TCC solenoid replaced today and it shifts very smooth. Thanks for the advice from everyone. However, I received bad news when I picked up my car this afternoon. It is not engaging into 4th gear for the most part. I do not do a lot of interstate driving, mostly local, so I haven't really noticed any problem.

So now I must decide whether to rebuild the transmission or with almost 96k miles go for something else. Any advice is appreciated. It seems like all I do is ask questions but I do appreciate it. Thanks.

Did they replace the 3-4 shift solenoid. I believe there's a 1-2 and 3-4 shift solenoid so if you're not going from 3-4, the shift solenoid would be the first place I'd look.

Sorry to say this could have been avoided by getting a full scan done by a trans tech, the trans scanner can command shifts and confirm solenoid operation and gear engagement, pinpointing whether there is an electrical or mechanical problem.

Definitely not good news without overdrive. Fuel economy will take a big hit.

I agree with StevePT that it is probably the 3-4 shift solenoid. A rule of thumb is to change out all solenoids once the effort is made to go into the side cover to replace the PCS and TCC. It's funny that the 3-4 would act up after a TCC and PCS solenoid are replaced. The 3-4 shift solenoid is located at the opposing end of the valve body. I do not believe that it is a major mechanical problem that requires a rebuild.

Another suggestion is to disconnect the 20 way electrical cable (umbilical) to the tranny and reseat it. The lows that control the shift solenoids pass through that connector. It is removed when any side cover removal work is done.