w204marianne

Hi all,

First time posting here. Took out my w204 2011 C350 4MATIC to a parking lot last night after figuring out how to enable Dyno Mode via the secret menu. This was my first time trying to intentionally slide a car so I was just trying to practice.

Anyways, sort of got the hang of it the first few times. I have an auto transmission so I was really just flooring it with sport mode on, followed by jerking the wheel right or left and then fluttering the gas pedal. Something weird occurred twice though: after flooring it, the throttle output was severely reduced afterwards. Even putting my foot down would barely give the car any go at all, it was pretty much just crawling. I turned the engine off and restarted it, which fixed this issue immediately.

However the second time this occurred, upon restarting for the second time the check engine light came on. This morning I found out it was likely the gas cap that came loose, as I tightened it and started the car with no engine light on.

Is there something about Dyno Mode that limits throttle output after a huge throttle input? Has anyone experienced something similar and do you know why?

FYI - last night I turned dyno mode off and let the engine cool off once the check engine light came on. After starting it again the light was still there, but the engine sounded completely normal, acceleration was fine (even after flooring it, which I did multiple times to see if the car would start to crawl). No weird noises, car drove fine.

Odd Piggy

Dyno mode turns off ESP/ABS/BAS and the front/rear wheel speed comparison logic. Everything else should work as designed. It is intended for only 2 situations: 1-performance testing with the car secured to a dynamometer test rig; 2-straight line acceleration testing in a controlled environment. Both of those are to obtain information for optimizing engine parameters. Something else put the car into limp mode. The loose gas cap won’t do that. Maybe the transmission saw something it didn’t like, or maybe the cats overheated. The car is probably fine.

w204marianne

Thanks for the reply,

Still newish to car lingo, by cats do you mean the catalytic converter?

But good to know. Maybe the transmission didn't like me turning sharply as I was flooring it; I'll try giving it a bit more running room before turning.

Odd Piggy

Yes. Cats = catalytic converters.

BTW - be careful in that “secret” menu (the engineering menu). There are settings in there that can really mess things up.