DJ BIS

The lady took the 2009 C300 Manual 6-Speed for a ride, got into a little battle with a Xion TC that whooped her ***.
She is no wimp, having driven a few V8's in the past, I'm pretty sure she knows how to put the pedal to the metal, and has the tickets to prove it, lol.

Her reasoning for losing against a 4 cyl? "I think that little Xion had a Turbo! That's what TC means, right? Turbo Charged..." and "The stupid car (benz) kept cutting out and throwing me off every shift!!!"

So I asked:
"Like what? Was the car's RPM limiter kicking in?" (basic assumption...)

She said: "Is that what that is?!!!!"
Me: "Maybe, let me take it for a run..."

Indeed. Second and third gear high-RPM pulls are all I needed to do in order to feel the horrible jerking as the fuel is cut-off and the stupid RPM limiter kicks in... Not even reaching the red-line! WTF?

I mean, I can understand MB trying to protect the engine at RED LINE RPM, but 5,500? Pshhhhhh.

What is the consensus when it comes to this? Is this engine unable to reach Low Red Line without exploding? Is the factory RPM limiter low by default and way over protective? Has anybody been able to change it easily?
Would you recommend against modifying the limiter?

I don't know, it's just false advertisement in my opinion.
If my instruments tell me I can reach a certain level of performance from the engine, I expect to attain it and not be rattled scared into accepting something lesser.

My lady will now be seeking sweet revenge from all "Turbo Charged" drivers. lol

thesaintusa

There is something wrong with the car if it cannot hit the red line.

If the ECU is limiting the maximum RPMs that can be reached it is because something (sensor) is telling it to do so.

Antique-Ace

Let me first say that I do not condone street racing.

That being said, the "TC" in "Scion TC" does not stand for "turbocharged". I think you will find the majority of Scion TC's on the street are not turbocharged and have the stock NA engine (1st Gen: 2.4 liter I4 2AZ-FE producing 160 hp and 163 fl-lbs torque, 2nd Gen: 2.5 liter I4 2AR-FE engine producing 180 hp and 174 ft-lbs torque).

There are several forced induction mods for the Scion TC with one of the more common ones being the TRD (rebadged Vortech) supercharger kit which is listed to boost engine output of the 2AZ-FE to 200 hp / 185 ft-lbs torque.

Ders

I've got the same car. I know what you mean about the RPM limiter but I only notice it when in neutral. In neutral I can only rev it up to ~5.5k like you said. However if I'm driving I have no issue getting well above that in any gear.

DJ BIS

Cool facts list. Maybe the weight advantage was on his side? LOL

DJ BIS

In contrast, we have never needed to rev the car to red-line while sitting on the driveway. I need that to happen when I'm actually driving the car.

Are there any other manual transmission drivers that can provide their feedback?
This is really bugging me now.

DJ BIS

Anybody else that can help? Would be nice to know how I can remove this "RPM Limiter".

vipsa

Get an ECU flash. All of the ones I've seen not only remap your fuel/air ratio, but also remove the RPM limiter or at least raise it above the stock level.

DJ BIS

I take it that it is not a procedure that Mercedes Benz does... I have to take it to some tuning shop? (I have no idea where I would go to in Delaware).

If I did not want to flash it, there is nothing the dealer can do for me?
Or any electronic tools that allow me to raise it myself?
Ugh, why was it set up like this to begin with?

thesaintusa

To clarify,

When in gear and driving you cannot go above 5500 rpm?

dudeitsmattx

If you are driving in gear and your car won't go over 5,500 RPMs there has to be something wrong with the car. That is not normal at all!! In park and natural yeah but not in gear driving down the road.

DJ BIS

I can't say its always exactly 5500RPM, but close. Could be a little higher, around 6000...

thesaintusa

Something is wrong with the car. Codes?

aamirani

Doesn't sound right, get it checked out by the dealership or your mechanic.

MDMercedesGuy

A few things to add

• Unloaded revs are bad, hence the 5,500 RPM limiter standing still.
• The C300 is not that fast of a car - even with a manual. It is heavy, and out of its element when being asked to do something as incredibly stupid as street racing.
• The rev limiter is there for a reason - we're not talking an engine with lightweight internals here that is made to scream. Cutting off at 5,500 is early - but we're talking 1,000 RPM top the factory limiter. You're way past the torque peak and almost reaching the HP peak at 5,500 - there isn't much more to give.
• Did I mention that street racing is beyond stupid?

Skyline45

Hmm, never seen this happen before in my car. While I never really "gun-it", partly because the C Series is not really designed for speed with the exception of the C63 of course, when I do get into it my RPM's climb higher than 5.5k. In both Auto and Tiptronic mode. Granted... it does take awhile to get there in Auto mode >.<

DJ BIS

Point taken. You advise me not to be stupid and hurt somebody or damage anything by pushing the engine past what it can currently achieve. I am cool with that. I don't condone street racing either. Nobody is making it a practice here. I also don't enjoy stressing the vehicle.

But from a technical perspective the question still stands. Why does it do this when it shouldn't?

DJ BIS

Correct. This is a manual trans. Not that it will make the difference regarding this limiting issue... just looking for some ideas.

I appreciate all the feedback!

thesaintusa

Take it to a shop / dealership as it is not normal to have the RPMs limited below the rev limiter.