dmingo777

I recently had the valve body replaced on my 05 SL500 7-speed transmission. Ever since, the smooth shifting and acceleration have been replaced by erratic shifting and slow/delayed response. When I slow down for a stoplight or corner and try to accelerate, the car hesitates to engage and has several times led to dangerous situations. After almost a full second of delayed response (feeling like a lifetime), the car finally bolts dangerously ahead. I'm sure that my moment of panic causes me to press the accelerator harder.

In addition, the car shifts harder and the smooth transition between gears has disappeared. Normal shifting use to happen between 2000 and 2700 RPM (for my driving style), but now shifts prematurely into a higher gear, losing the power curve. This is frustrating.

This amazing car has always given me the performance I needed to get out of tight spots and operate with great confidence. The once immediate response is now sluggish. I have taken the car back to the dealer twice to have the speed sensors reprogrammed, assuming that something within the transmission was at fault.

Now I'm wondering if the problem could be the car's throttle actuator. As I think about this, the engine doesn't respond to my foot's position or pressure on the accelerator; the delay to rev up has put me in harms way several times. When I need to shift down to a lower gear, I have to manually do so as the accelerator doesn't respond to my foot the way it use to. Could this be a misbehaving throttle actuator? If so, why hasn't a malfunction shown up on the dash or on my diagnostics meter?

Any help?

Rudeney

You need to resync the accelerator pedal with the throttle body. You can try the steps below, but I am not sure they work on the R230. If not, it has to be done with SDS.

1. Make sure everything in the car is turned off and closed.
2. Turn the key to position 2 so all the dash lights are illuminated.
3. Press the accelerator fully to the floor, depressing the "kick-down" button.
4. Hold he pedal for 5 seconds and continue to hold it down.
5. Turn the ignition switch back one click to position 1.
6. Release the accelerator pedal, but leave the key in position 1.
7. Sit quietly and wait for about two minutes - do NOT open or turn anything on.
8. Listen for a "click" or "ping" noise form the dash.
9. Start the engine and drive the car for at least five minutes.

Ghostty

The reset function works, as I tried myself a while ago, but forgot the step I was missing - leave the key for 2 mins or so.

Didn't know it synchronizes the gas pedal, I used it for erasing the transmission memory, as its function drives me nuts! Nobody drives around town flooring the gas pedal on daily basis, so the transmission learns that, and when you, while driving, floor the pedal - it will not downshift nor raise the rpms above 3k! Imagine that feeling when you need to suddenly accelerate.... Hate it!

Thank you again, Rudeney

Rudeney

My understanding is that procedure does nothing for the TCU - it just re-syncs the throttle. But maybe by doing that, it somehow erases the throttle-to-TCU mapping. I tried it on my MY2011 SL550 and got nothing. On the MY2002 C240, it makes it drive better for a while. I never notices any differences on the CLK550. I was poking around in SDS and it has a throttle sync function. I may try that someday as I sometimes experience some oddities accelerating at certain speeds in certain gears. Then again, I am thinking of getting a Sprint Booster because I'm just tired of the whole 2-second delay when pressing the accelerator.

tandan

Rodney, thank you. Your timing is exquisite. I just got my car back from the dealership and it felt lethargic. It was like I was in comfort mode rather than sport. I was thinking about doing an ignition ecu reset but was not exactly sure about the sequence. I followed your steps and the monster has returned. God I love this car!

Ghostty

You might be right - it might just be a regular resync of the pedal. Now regarding your cars - do all of them have the same 7 gear transmission? I have doubts that your MY2011 SL550 has a 7 speed, more likely a 9 speed. And the C240 should have a 5 speed (?). I know for sure that it works with the 5 and 7 speed transmissions. Maybe they updated the TCU for the later years, so it gives no results for the later models.
And for me it does make a difference in driving styles, just like tandan mentioned - comfort vs sport.

Aaaand what is a Sprint Booster?



Regards.

Hary Gahtoe

Before i start I have to say this first;
There are always Alt Right types who will shove their opinion down everyone's throats and shout you down like some guy Alec Baldwin portrays. Unfortunately there is such a person on our forum who vehemently denied any usefulness of any form of signal amplifiers which is what the units function is.
Don't take my word but don't allow someone else to bully you and diminish your right to choose either

Now, that we've cleared the air
I HAVE one. Used it for >6yrs. Caveat being it truly wont "up" the HP/TQ BUT.....
It will access more power, faster the engine and trans has, that the ECU PULLS OUT of the calibrations and allows the throttle to operate pretty much instantaneously.

I love how it makes the car react. It speeds up the initial signal to the DBW throttle but tapers off so as not to cause an overly twitchy feeling higher speeds

Truth; I get instant off line snap and can spin the tires right up to second gear. Without it. I could stab the gas and all I got was a bog; little squeal, that was it. And yes i tried a re set many times to no avail.

I have no affiliation with this manufacturer or receive any compensations i just feel others need to know it works on my car

Rudeney

The C240 has the 722.6 (5-speed), the CLK550 had the 722.9 (7-speed), the SL550 has pretty much the same 722.9 as the CLK550, except that it has the "sport shift" option with manual mode.

Hary's post explains the Sprint Booster. I have not tried it yet, but I think I might. I get really annoyed with the throttle delays, even in sport mode. My friend Yidney over on the W209 forum puts it this way:

Like Hary said, the Sprint Booster doesn't increase HP. It simply improves throttle response by remapping the signals from the accelerator pedal to the throttle body. If you read the information on the Sprint Booster website, it seems that this problem is not specific to MBZ - many other makes with throttle-by-wire systems would seem to be affected.

Ghostty

Sounds like really fun to put it, because waiting in line for some throttle response is not that fun...

but $300 for something like that? Bit overpriced?....

Rudeney

One word: Capitalism. If I had invented the thing, I'd probably charge top dollar for it, too!

Ghostty

Now $240 it's already better


http://www.ebay.com/itm/Sprint-Boost...p=mtr#shpCntId

Hary Gahtoe

That's a better unit and < $$$ than I paid 7yrs. ago

I know; to someone who hasn't used one $240 sounds like a lot but after you buy one, nobody could offer you enough cash to part with it. It makes a good car an awesome car.

HKS also makes an adjustable unit for 3SG"s Evo's & STI's but not sure if they do German

Rudeney

It's coming from Greece, so with with international shipping and (potential) customs fees, those of us in the USA are likely better off buying direct for $289 with free shipping:

https://www.sprintboostersales.com/S...r_V3--SPRME033

Ghostty

ordered. Paid. $240 ��

P.S.

I'll spend the extra $60 for a tank of gas to go somewhere