Losiracer2

Good Job! I like how you logically progressed through all the problems and started with each subsystem in the car to rule that out.

It does make me worry about my 97 ECU now, which may be causing my shift solenoid issue CEL P0770. I really hate to do all that work, especially since the previous owner before me said he changed it out not too long ago (unfortunately received no records with the car however). But with my car having about the same mileage as yours, 276k, and being from a hot desert climate, it might have compromised the integrity of the soldering connections and the caps may likely be on their way out.

What is your background if you don't mind me asking? Engineer of some sort?

M4rk

Thanks, guys! I am happy to share and also very glad the car is back to normal.

@Losiracer2: Cyber security, actually - ethical hacking/pentesting.

dicer

With the first post I thought you determined the crank sensor was okay.

M4rk

Or so I thought as it was providing a reading. Only after the sensor was removed and cleaned, RPM reading during cranking stabilized, versus the fluctuations I observerd prior to the fix.

I am talking about reading constantly jumping between 90-140 RPM, versus 160 +/- 1 after the fix. Live and learn.

dicer

Its one of the first things to suspect with no start and sporadic running, ie dying at stop lights etc. It is a known problem on early 2000 Mercedes cars, and I've had to replace one onetime because of sporadic running problems. In your video, it sounded just like my on 1990 when I put an ecu that was not in good shape in to try it.
That is why I so strongly suggested the ECU, and of course depending on what circuits are bad in a bad ECU it can do what ever a bad crank sensor can do, and of course anyother sensor as well.