Recently, in my good friend’s car with about 90k miles on it, (he doesn’t abuse or neglect it) he started getting the “GM morning sickness” as I used to call it… But his car is doing it warm or cold, shudder and slip leaving from a stop, and he has to feather the throttle and keep a light load.
He put up with this for a while before I noticed it one day while we were riding around.
He did some research, and found several people had had improvement by adding the Lucas trans treatment, so one afternoon, we sucked out about a quart of the fluid (I had serviced the trans about 2 years ago, but now he only drives about 400 miles a month.) which didn’t seem to smell or look burnt, and refilled with Lucas.
He drove it for a few weeks, saying it was slipping less, and was acting a bit better, but today I noticed it wasn’t slipping as much, but wouldn’t go into overdrive unless under almost zero load, and the lockup would only kick in intermittently.
Also, I noticed the speedo would drop almost to zero when it started to slip.
One other thing that has been constant throughout all of this, when climbing a steep hill, such a residential area, the car will no longer downshift from second to low gear.
I know the speedo is not cable operated like older cars, so the fluctuation is giving me hope, and I’m hoping it is something besides a complete rebuild.
I am just curious if anybody has experienced this being hopefully just a solenoid of some sort, or am I correct in my opinion I gave to him that it is on it’s last legs.
The speedometer dropping to zero is a major clue. I’m suspicious of the vehicle speed sensor (VSS) It is one of the sensors controling shifting in addition to sending a signal to the speedometer.
My wife had a similar problem with her '94 Olds Cutlass Calais and the problem was fixed with some advice from @transman618 . He suggested pouring in a can of Berryman’s B-12 Chemtool. I did and the transmission worked perfectly for another 10,000 miles. It’s still working because I speak to the woman who bought the car from my wife from time to time. I gave the transmission the treatment over 4 years ago. It works. Thanks @transman618 wherever you are. BTW…disregard the fact that this treatment is made as a fuel treatment additive.
If the vehicle speed sensor is acting up it will effect the transmission shift points.
PURPOSE:
The Vehicle Speed Sensor (VSS) provides information to the PCM for control of transmission Torque Converter Clutch (TCC), speedometer, odometer and cruise control.
OPERATION:
The VSS is a Permanent Magnet (PM) generator that produces a pulsing A/C voltage whenever vehicle speed exceeds about 3 mph (5 Kph). The A/C voltage level and the number of pulses increases with vehicle speed and is converted by the PCM to MPH (Kph). A VSS buffer is incorporated into the PCM for operating the instrument panel speedometer and odometer.