Hello everyone! I have a 1994 Pontiac Bonneville se with 120k miles. Every now and then I will have the check engine light come on and for a split second while driving and my speedometer will jump by about 20 mph for a split second. the car sound dings and I lose power for a split second when it does this.

Other times it will stall when coming to a stop and when idling at a stoplight. Any ideas?

Sounds like an electrical ground problem somewhere. How old are the battery cables and battery?

Battery is maybe a year old now? Battery cables are original except that a battery cable saver was put on to replace the corrosion on the end of the cable.

When it stalls is it just like flipping a switch ... it doesn't stumble or hesitate, just shuts right down?

Pretty much, no warning, it just shuts off. Sometimes after I restart the check engine light will be on and then I have to turn everything off, open the door, and then restart. Sometimes its a few months and then sometimes it'* the next day that it starts acting strange again.

Crank shaft position sensor.

When the CPS fails there is no spark at all, and the failure will be intermittent. In early stages it can fail and recover so quickly the engine will stall and re-start on its own right away. It can also fail where the engine will stall, but restart after a few minutes. It can also fail where the engine won't start, but 10 minutes later it will.

The CPS is located behind the harmonic balancer (crankshaft pulley). You access it through the front passenger side wheel opening. The hard part is getting the balancer off, changing the CPS itself is simple. Not an overly difficult job, and we have a write up on the forum on how to do it.

Here is a link to the writeup on how to change the CPS:

https://www.gmforum.com/mechanical-1...sensor-279066/

Damn, just got the balancer replaced last year too.

That still doesn't explain why my speedometer jumps when the check engine light flashes does it?

That'* why I was suspecting a ground issue somewhere.