C200 Stalling when revving
 

Good evening!

I recently switched a faulty coil along with the PMS ECU on my benz c200 -96. The car did run on four cylinders again, however another problem occured. The car idles pretty low at 5-800 and has always done that. The idling is pretty stable, moves up and down just a tiny bit but doesnt stall at all. The problem is when I press the gas pedal too quick the car instantly stalls. When I press the gas pedal veeery slightly it does rev up like normal and does not stall when I release the throttle. It's only stalling when I press the throttle too rapidly. Can this have something to do with the new ECU? (I can add that the car showed these symptoms with the old ecu this winter when it was very cold outside, but just for 10 brief seconds after first startup in the morning. Usually when I had backed up out of my lawn with very moderate throttle the issue dissapeared.) Anyone knows if unplugging battery for 30 mins can do the trick? Someone mentioned about reprogramming the new ECU or can there be other issues that match these symptoms? I'd really like to get the benz back out on the road again..

Sincerely, James

James,
Welcome. :)

Yes, you can do this. disconnect the battery overnight and then reconnect in the morning.
Others have done this with positive results. Keep us posted.

Did disconnect it for two hours with no luck. Maybe you have to have it disconnected for a longer amount of time?

James...... (in bold above) ;)

haha alright, thank you!! Will do as we speak and reconnect first thing when I come home after work tomorrow :) Will be aprox 20 hours!

Good day again. Just came back from work, plugged in the battery after 20 hours with no luck. I've noticed that the car's having trouble starting everytime the engine is cold. Takes me three tries everytime. After the first startup it does start like normal again. I also noticed from revving it to high RPMS (achieving this by very moderate throttle. Once I put a millimeter too much it stalls) I saw little bit of anti freeze coming out of the exhaust... Another thing I can add is that if I put the old ECU back in, the car runs on 2 cyls as expected, but does not stall when revving!! I think the car goes into some "limp mode" that maybe needs to be re-programmed ?

Does anyone have a clue what this can be?

Many thanks,

James

Forgot to mention that I only switched the faulty coil that ran cyl 1 & 4. Harness was good. I did not measure resistance on the remaining ignition coil but since its up running on all four with this ECU I dont think thats the issue. I just thought it's always good to give lots of info for easier troubleshooting. Maybe the ebay seller gave me a faulty ECU, and that would be totally devastating...

Scan for saved codes and post here.

Will do. I've come to the conclusion that it may the Throttle Position Sensor. But scanning first would be a smart idea.

Agreed to the scanning. Always a good, smart investment if you're going to DIY and/or ask for assistance on these forums.

Crank position sensor (CPS)..... that's what Western Hemisphere drivers call it. :)
Could also very well be the MAF too, or vacuum line leak (that you can't see), cats....