TonyRome

Hello, I own a 2011 C300 Sport. Last week my tachometer started bouncing rather slightly, but noticeable. I'm also feeling the car "lope" or sorta hesitate.

I own an iCarSoft i980 and pulled the following codes;
0524 - Diagnosis of tumble flap...
5945 - There is an internal fault in the control unit "N30/4 (Electronic Stability Program Control Unit/. Stored
5001 - There is an internal fault in the control unit "N30/4 (Electronic Stability Program Control Unit/. Stored
7208 - Check codings in control module Engine Control module

I believe the stability system codes are due to a fault I had previously when I got my ABS module wet. The ABS light came on until I dried out the the module connections. As for the 0524 code, I've seen some write ups and videos related to the C350 cars, but not C300. Could this be causing the RPM bounce & hesitation issues?

I also have a hard start issue that occurs periodically. I believe it's fuel system related, but need to pressure test the system.

ItalianJoe1

Your car has the tumble flap unit, yes. It usually doesn't affect idle, but it depends how/where it failed, it may be leaking or half closed and causing you to get the erratic idle.

TonyRome

My idle is fine/steady, but when I drive at a sustained speed it bounces.

Alfadude

When you say it "bounces" how do you define that? Are you talking the tach jumps back and forth 1K or more RPMs even when driving at a steady state or are you talking the tach needle moves slightly, like less than 50-100 RPMs, but it moves enough that you can see it is not 100% steady even when driving at the same speed on the highway? If it is the latter, I can see that mine does that even though I can't perceive any issue or change in performance. I was thinking that was just how the tachs on our cars worked. Not 100% certain on that, but can't say that I ever really looked on other cars I owned. I just happened to notice on mine when I saw something that another member posted about that and then I checekd mine and saw it did the same thing.

pezzy669

My '09 has a slight bumping around (50-100 RPM) at any speed from idle in park to steady freeway cruise, I have just chalked it up to normal older age operation. Don't think its anything to worry about, just an annoyance for observant types.

michail71

It could be a vacuum leak perhaps even unrelated to the codes.