1995 Cadillac STS stalls at low RPM

ALDRUMM

MEMBER
1995 CADILLAC STS
V8
FWD
AUTOMATIC
202,000 MILES

When the car comes to a stop and then the gas peddle is depressed to continue but an immediate stop is necessary, the car, in most cases stalls. During this process, the gas peddle is trying to move to compensate for this stalling situation. Generally the car does stall, although not all the time.

We have put a new fuel pump, fuel filter, EGR valve, new spark plug leads. Problem still exists. While it is not the end of the world, the car runs fine on the highway, or going up a hill with your foot firmly on the gas. It's only at this low RPM and the depression on the gas and then the sudden having to stop right after that movement, that the car stalls. It is somewhat of a safety issue, so we would like to get it solved. One other thing.I did install a device in the air breather boot about 2 years ago that purports to give better gas mileage. There was no problems after this installation. The problem did start about 1 year ago, and has been getting a bit worse ever since. Although we had it in to a GM dealer today, and the mechanic could not get it to stall. I don't know if he was able to duplicate the exact situation for the stall. Any ideas?

1 Reply

FACTORYJACK

MECHANIC
4,159 POSTS

If the throttle switch in the ISC motor is showing that the throttle is at rest, when it is not, the shaft will retract fully. The PCM(ECM) thinks that since the throttle switch is showing the throttle at rest, it should be in control of engine speed. Since the engine speed is high, it is going to keep retracting in attempt to make a change. If fully retracted, the throttle plate closes fully and a stall is the result. Once the speed is shown too low, or 0 at stall, it extends to try and bring the speed up. It sounds like a faulty ISC.