Please help. My wife and I have a 1986 Cutlass Ciera with an engine size 4 -151, 2.5L engine with 41,749 orginal miles. The car belonged to my wife’s mother and when she quit driving we had the vehicle shipped to us in Kansas.
Right after the transmission shifts at around 30-35 mph it locks up (for a lack of a better word.) This lock up can continue to about 40 mph. It feels like it ‘misses or hesitates’ until I let off the gas and increase speed again by going faster than 40 mph. The GM service department said there was a recall sometime ago to solve this problem but the fix was only for the larger 4 liter engine and to use this fix would damage the cars engine. They said it was not a transmission problem and that we will probably have to ‘live’ with this condition which is more a nusiance then anything else. They go on to say this condition will not harm the engine. Are they right with their answer or can something actually be done to fix this problem? Other than this the car runs great. It has been tuned up, all belts and hoses replaced, new thermostat, etc. Also, when we turn on the ignition, the engine would race at 2,000 rpm until we let it warm up and then put it in gear at 1000 rpm. A new thermostat has helped keep the idle from going so fast when we start the car. Is the fast idle normal for this age of a car or could something be done for this also. thank you.
Transman is the best to answer this but I believe what you describe is a shutter during the torque converter lock up. This was a common complaint in the 80’s when they were trying to improve gas mileage by taking any slippage out of the transmission as soon as possible. It would be more noticeable with a smaller engine. So guess the answer is to live with it.
The higher idle at start up could be due to a dirty idle control solenoid so you might want to have that checked and the throttle body cleaned of carbon.
My wife’s '87 Chevy Celebrity with the 2.5L has the same issue only instead of 40 MPH her’s does it at 35 which is really annoying considering the speed limit in most towns is 35 MPH.
While driving as you normally would, when this problem occurs lightly touch the brake pedal while continuing to accellerate. What i mean about lightly touching the brake pedal is to use your left foot and just kinda rest it on the brake pedal. not enough to apply brakes but enough to turn on brake lights. This will cause torque converter clutch to disengage.