94 850 stalling

[rlwhalen]

My 1994 850T with 155,000 miles on it developed a dangerous problem. When stopped at a traffic light or during deceleration at high speed on the highway, the rpm would sometimes drop and the car would stall unpredictably. It was usually easy to restart by shifting into neutral and cranking it over, but on the highway, it was a serious situation. After this happened on an elevated two lane highway, I was reluctant to drive the car anywhere where it could not safely be pulled over.

The fuel pump and fuel injection system seemed fine, and when running normally, the engine was very smooth. After reading about MAF problems here, I pulled the MAF unit and cleaned the sensor using an electrical contact spray cleaner. I also checked the throttle plate and spray cleaned it also.

This totally eliminated the problem. I will replace the MAF at some point soon since it is original equipment, but the idea that the MAF does not affect driveability is just not correct.

[rspi]

Do you have a CEL? If so you need to check the codes.

The MAF can cause stalling. It controls air to the motor.

Also, what does "seemed" mean?

[rlwhalen]

The CEL was not on, but the problem was intermittent. The fuel pump had been replaced some years ago, and it was running normally, supplying gas to the fuel rail. That's why looking at the MAF or throttle plate made sense to me. I suppose another culprit could have been the idle control valve, but it also had been replaced 3-4 years ago. At age 19, there seem to be as many electrical gremlins as mechanical ones, if not more.

[rspi]

All because a part was changed 3 months ago doesn't mean it's not failing now. I had a ETC that lasted an entire 3 weeks.

Random stalling with no codes is more likely a bad fuel pump relay.