alkrstev

I've been having some serious issues with sluggish acceleration and little to no response when I push the pedal. Most times, the gas pedal is really soft. When I push it, it will not downkick, and the car accelerates very slowly (In D and S mode). It throws no CELs. I have to almost floor it in order to get a downkick (BTW i also have a new tranny, intercooler, and torque converter). If I floor it then everything is fine and the car is fast again. I do not think it is a bad IC pump, because it has already been replaced and the supercharger does not turn off, but it sounds like the car is searching for a gear(vacuum cleaner sound ) when I step on it half to 3/4 way on the throttle. For example if I am driving around 20-25mph and I step on the gas slowly 3/4 of the way, the car will struggle to get up to speed until I push it almost all the way (kick down button). On the highway, it is annoying when trying to pass cars, because it takes almost flooring the car. It has really been bugging me and I have researched everything regarding this problem, and concluded that the fix would be in getting new throttle position sensor. Do you guys think this will solve my issue, and if it will, how much does it cost? I would really appreciate your help as this is making me not like my car so much. Thank you in advance.

jimmyp

Sounds like your coolent pump

SilverBulletAMG

TPS (Throttle position sensor or something like that) - FrankW has a long thread on this I believe. Could be the pump if it's worse when car warms up.

CLKCLK

jk...

By the way, do you discover this problem after you have all these done or you just discover the problem by now? I mean it was running fine with all these new stuff before?

TopGun32

buy an OBD2 scanner..

if there is no CEL yet.. then check your IAT's.

TSP will throw a code and also bad wires or plugs..

SickSpeedMonte

You should be able to diagnose the TPS with a multimeter, no? It just outputs a voltage. Better than throwing parts at the thing.

boohooramblers

So, the issue seems to be the 'distance' traveled by the accelerator pedal?
i.e. Push a little - wimpy acceleration; Push to the kickdown simulator - the car takes off.
When you say the car accelerates very slowly, can we assume that engine speed (rpm) follows the same pattern?

Excuse the obvious, but......
Have you reset adaptations? (a.k.a. sneaky ECU reset)

The reason I ask is because:
If you normally drive like a granny, for 50% of pedal travel, you get 40% engine load 'released'.
If you normally drive like the 'Chicago-area-crowd' C32'ers, 50% pedal travel releases 80% engine load.
Thus, if the 'granny' mode is active, the accelerator will have to travel significantly more.
If your throttle body actuator did not open to the degree it should under WOT conditions, you wouldn't have normal power (however you say that you do when you floor the accelerator pedal).

If adaptation resetting doesn't do the job, then you could have an accelerator pedal sensor problem (sensor B37). Let us know if you need a schematic of B37.

alkrstev

I never really noticed the problem at the beginning until it really started bugging me. I thought because the c32 is supercharged, it is supposed to be like that. My brother has a C320 and the gas pedal is not like that, it responds right away and kicks down properly when pressure is applied on pedal.

alkrstev

Thank you for your response boohooramblers. I definitely do not drive the car like a grandma. I drive it very aggressively most of the time. The rpm's climb slowly under 50% or less throttle. I have done the sneaky ECU reset multiple times, and while the car responds slightly better, it feels like there is no torque at low rpm's (unless I start from 0, or use the stick). I have to push the pedal 3/4 of the way to get any response besides sluggish acceleration. Another concern is why is the gas pedal so soft? Could you please give me a schematic of B37? Thanks.

alkrstev

BTW, thanks to all you guys for the responses. Greatly appreciated.

boohooramblers

My understanding is that the accelerator pedal sensor (B37) is basically 2 glorified potentiometers that sends a signal to the ECU (as illustrated below) based on voltage.
This leads to the appropriate (or inappropriate) efferent signal from the ECU to the throttle body actuator (M16/1).

Out of curiosity, you wouldn't happen to have a 'SprintBooster' installed, would you?

alkrstev

No, my car is stock and I don't beleive it came with a sprintbooster from the previous owner. Where would the sprint booster be located if there was one installed?

SilverBulletAMG

Plugged in with the throttle pedal. Take a peek at the base of the pedal. Not likely you have one if it wasn't mentioned to you though.

alkrstev

Thanks again for that image Boohooramblers. I guess it could be the B37 sensor. But does it have anything to do with the softness of the pedal? I guess I am going to have to call the mb dealership and ask them how much it costs, but they will probably want to replace the entire gas pedal assembly.

alkrstev

I am going to check up on that as soon as I can. Probably this thursday, but I dont think I have one installed.

1qikctr

Hey boohoorambler, do you think the sprintbooster will effect the gas pedal? B/c when i had my TPS changed,( it was the complete set) they do not sell the senser by itself. Anwyaz.... just thought i thorw this qs in here, if the sprintbostet would effect the tps... since i have one in the car.

boohooramblers

The SprintBooster is, in essence, the world's most expensive potentiometer! (written from somebody who has one!)
The SprintBooster merely gives the 'feeling' of being faster; however, it doesn't do anything except 'amplify' the signal coming from the accelerator pedal sensor per unit distance traveled.
i.e. you get full throttle response by the throttle actuator (M16/1 in the diagram above) about 25% quicker (assuming you're 'giving it the beans').

Importantly, you can achieve the exact same result by making the accelerator pedal travel further the old-fashioned way!.
So....the SprintBooster basically tells the ECU that the gas pedal has traveled further than it actually has.

Gramma_Benz

I'm having my TPS fixed right now. I'm on vacation so I had my mechanic send out my TPS to BBA Remanufacturing for a rebuild. $400 for the rebuild plus labor. I think labor is about $160.

Let you know how it goes.

c32used

Very true but boy the Sprintbooster feels sooooo good

1qikctr

Thanks for the reply, So, the sprintbooster does not effect the gas pedal. I thought it can cost the TPS problems in the long run. Guess not from what your explan.

FrankW

you mean you are having the throttle body rebuilt? or the pedal sensor rebuilt?

anyway, as most of you probably already figure out. OP's issue is with the sensor on the pedal, not the throttle body itself. The issue I had which was mentioned threw bunch of codes which was related to the pedal as well as oil leak causing TCU to go haywire. For whatever reason I also got a new TB out of it.

FrankW

you mean you are having the throttle body rebuilt? or the pedal sensor rebuilt?

anyway, as most of you probably already figure out. OP's issue is with the sensor on the pedal, not the throttle body itself. The issue I had which was mentioned threw bunch of codes which was related to the pedal as well as oil leak causing TCU to go haywire. For whatever reason I also got a new TB out of it.

you can't get the sensor on the pedal by itself from parts, but if you do have warranty the dealership only replaces the sensor itself which makes you wonder why the hell I can't just spent less to get the sensor instead of the entire pedal.

alkrstev

I got a question FrankW, I still have extended warranty for another 20 days. My car is not throwing any codes, and mercedes says the car is fine and wont fix my problem with my gas pedal. How much does it cost to replace the entire gas pedal?

c32used

Sorry to revive this but I got the P0120 (Generic TPS/Pedal positioning sensor A circuit malfunction)and this thread being so long ago...I was wondering what exactly has to be changed? The accelerator pedal sensor or something else? BTW I do have a Sprint Booster.....but if I read correctly my problem isn't from that at all...I'm trying not to spend unnecessary money on parts I don't need...TIA

BTW since it's been 6 years since this thread was created do you still have to buy a full pedal or are individual parts sold?

c32used

P0120 (Generic TPS/Pedal positioning sensor A circuit malfunction)