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Discussion Starter #1
Let a friend take my S430 for a spin the other day and he floored it a few times. I started experience acceleration problems maybe because I was low on gas so i filled it up and it went ok but now when i floor it I no longer feel that rocket take off its smooth. Is there anything wrong with my car? Or is it normal?
 

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W221 & Audio Moderator
2013 S550
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I trust that you used the proper grade of gasoline when you refilled, so I'll move on.

First, check to see that your friend did not set the transmission control button on the console - the one labeled "S" and "W." It is a plunger switch, not a rocker switch - it moves straight up & down, and will change the indication on the lower right side of the instrument cluster. If he changed it, slap him upside the head. It wont hurt anything, but he should keep his hands off the adjustments in your car.

If that doesn't fix it - Your transmission adapts to your driving style, automatically. Your friend's rough driving may have caused an unwanted adjustment. You can continue driving, doing nothing, and it will eventually readjust to your style. Or, you can reset the adaptive feature using the "Resets" link in the W220 S-Class Encyclopedia sticky toward the top of the W220 forum page.

Once you reset, if you do, it will again take some time to readjust to you.

Try those things and let us know how it worked out.
 

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Discussion Starter #3
Hi thanks the for reply. Do you mean the button labeled C and W? Doesant seem like hes touched it haha. Still hasnt fixed it though may try resetting the transmission however before I do, do you think that the quality of fuel may have an impact? I previously had Exxon Supreme in it but I was forced to fill up with BP Ultimate that time. Thanks
 

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W221 & Audio Moderator
2013 S550
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Yes, that's the switch. Some model years had different labeling, and you didn't provide your model year (something we'd request you add via your user control panel; also at least the continent you live on - it can affect an answer).

Fuel quality can have an impact, but if you are using the proper octane rating there would be no short-term difference between the brands you used.
 

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2004 S430 4Matic & 2001 SLK320
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It might be your mass airflow sensor is going out. My SLK just did this to me, and I am waiting for it to happen on the 4matic now. It started out months ago, as you mention, some sluggish responses. Then it started running rough when at idle, for instance at a stop light. Then it became hellishly sluggish at take off from a stop then shot out quickly like something got stuck. I took the sensor out, blasted it with cleaner made just for that (get at any auto shop. Pep boys, autozone, napa, etc.... for about $10) That made a difference for a couple of weeks. So I knew it was the sensor, when the problems came back, did not clean it, just ordered a new one from autohausaz instead.
 

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I'd double check the transmission mode switch position. Depending on year it's either S/W or S/C, but the function should be the same. "W" or "C" causes the car to skip first gear and start in 2nd. It also causes the tranny to upshift more quickly. All of these things sacrifice some performance for economy, especially off the line.

On my S500 there was enough torque so that performance was excellent in the "C" mode and I never used "S". Going from the 500 to the 430, putting the 430 in "S" gave it the same performance characteristics as the bigger V8.

I doubt fuel is the issue, although some cars will step down engine performance as a precaution if it senses fuel of a lower octane than it wants. I'm not sure if our cars do that, but something to consider.
 

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W221 & Audio Moderator
2013 S550
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corkshoppe, of the buttons on the right side above the radio - the Central Locking Switch, the Antitheft Alarm System tow-away function, the Parking Assist Switch (if you have Parktronic) and the Rear Window Sunshade, which one is "like launch control?"

Or are you talking about the Eject, Telephone, Dolby, Tape and Display On/Off buttons above the COMAND screen?

A bit more precision would be helpful in seeing how your post had anything to do with Puckfack's question, or any of the responses.
 

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2003 S500 (255,000 miles), 2015 ML350 4matic (66,000), 2009 S550 4matic (110,000)
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TPS

Check OBD for P0123 ... throttle error. I have experienced this in "C"omfort mode when I kick it down. It defaults the computer to safe mode acceleration which is painfully slow. A simple key off and back on resets.
 
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