I have a 1991 buick century with 160,000 miles. It wasn’t driven for about a year and about 8 months ago I changed the plugs, wires and oil and it has run great since then…until yesterday. Now, everytime I slow down to come to a stop (or below 20mph) the car jumps and jerks and acts like it is wanting to lock up and stalls. It starts back up put everytime I put it in drive (just drive) it stalls again. I end up having to put it in neutral, rev the engine, then put it in drive real quick. Talking to my dad, who I got the car from, he told me it used to have this same problem and that is why he quit driving it. We have a couple of theories, but ANY help would be appreciated. Thanks!
My theory is a torque converter clutch that is stuck on, leaving the converter in lock up mode.
It would be kind of like trying to come to a stop with a manual transmission, leaving it in gear but not depressing the clutch.
The problem is most likely with the Torque Converter Clutch solenoid sticking.
The TCC solenoid is what directs the hydraulic pressure to engage the TCC. If this solenoid sticks to where it doesn’t release the hydraulic pressure from the TCC, the engine stalls because it would be the same as stopping with a manual transmission in forth gear without stepping on the clutch pedal. The engine shudders and stalls. Then when the engine is started it runs as long as it isn’t put into drive. Again, if the TCC solenoid is sticking, this would be the same as trying to start out with a manual tranmission in forth gear. The engine stalls. But if let everything cool down there’s no problem.
The cheapest thing to try to remedy this problem is purchase a can of Seafoam TransTune add the entire contents into the transmission fluid. The Seafoam may dissolve the gum and varnish that’s causing the TCC solenoid to stick.
I had the same problem with my 1990 Skylark about four years ago. It was doing the same thing, and replacing the torque converter clutch solenoid was the solution. My car has the TH-125C three speed automatic transmission, and replacement was as simple as removing the side cover, which was easily accessible on my car, and removing the old solenoid and installing new. Took about an hour and a half. I can’t speak for replacing the TCC solenoid on the 440-T4 four speed automatic, which was available in your car, as I have never done one, but the three speed is easy to deal with, and shouldn’t even cost too much if you have a shop do it.
Thanks. I know the basics so I’m not as knowledgeable, but my dad has the same theory.
I had the same problem with my 1992 Century about 9 years ago. It was a torque converter lockup problem. A simple transmission job solved the problem. There is a temporary fix you can try. My mechanic showed it to me. He showed me an eletrical connector going into the front part (towards the grill) of the transmission. He said it controls the lock-up mechanism. Simply disconnect it. Your highway gas milaege will worsen, your check engine light will come on but you won’t stall. He told me he’s seen many old GM cars with that connection missing because the drivers don’t want to go for transmission repairs.