My "87 S4 was doing something really weird last weekend. When coming to a stop and disengaging the clutch, the RPM would drop very low and sometimes the car would stall. Then, to make matters worse, every once in a while after the stall I would turn the key and . . notyhing. No lights, no sounds, no starter. It was if the battery was dead. So, I would disconnect the battery ground, wait a few minutes, reconnect it and . . . power! Interior light on, can starts right up. Weird.

It this a classic symptom of my ECU going? Or something else? Thanks.

 

No, the ECU wouldn't kill the whole car. Check the engine to frame ground. Positive battery cable connections at both ends. Study the battery cable along the chassis. Wiggle the cable, wiggle the ground cables. Wiggle the battery posts firmly (could be broken internally) to see if you can replicate the power outage. If the ground cables look at all ratty, replace them. Remove and wire brush all the main positive and ground connections.

 

Thanks for the tips, Bill! I will try them out this weekend.