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2001 E430, 2015 GLK350
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Discussion Starter #1
2001 E430 with 80k miles. I'm experiencing an intermittant problem, sometimes if I "floor" the accelerator pedal the car doesn't respond...it slowly and I mean slowly ramps up in speed. It only seems to happen if I give it full gas, partial acceleration happens normally. No CEL or other indications of a malfunction. Any ideas??
 

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'01-E320 & 02-ST2
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31,631 Posts
Check for codes...always, always, always the best place to start for a driveability issue.
 

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2001 E430, 2015 GLK350
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32 Posts
Discussion Starter #3
Check for codes...always, always, always the best place to start for a driveability issue.
I absolutely concur with that statement. I just will not have the time to do this until the weekend. I'm pretty sure there will be no code though...I checked for stored codes a few weeks ago after changing a MAF sensor and there was nothing there other than the MAF codes. I'm pretty sure this is a problem with the throttle by wire setup...has there been any common or known problems with the TBW system?
 

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2001 SLK 320(217K Miles), 2002 E320 Special Edition(183K Miles)
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3,467 Posts
I checked for stored codes a few weeks ago after changing a MAF sensor and there was nothing there other than the MAF codes.
Where did you get the MAF from? If from EBay, it most likely the MAF that's bad.

The TPS *Throttle Position Sensor) will throw a code if it is bad. It has dual circuits, so you should get normal acceleration even with 1 circuit bad, albeit with maybe a half to 1 second delay while the computer decides which circuit to trust. If both are circuits bad, it will not move at all, just stays at idle.
 

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1999 E55, 2001 E320, 1990 560 SEC, 2004 ML350, 2001 ML55, 1995 S500, 1998 SL500, 2010 E550 Sport zoo
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7,035 Posts
I would suggest you do a "soft" ECU/tranny reset procedure and see if that changes the performance.
 

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2001 E430, 2015 GLK350
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32 Posts
Discussion Starter #6
Where did you get the MAF from? If from EBay, it most likely the MAF that's bad.
I bought a new Bosch one from Autohaus, so I'm sure it's not the MAF.

I would suggest you do a "soft" ECU/tranny reset procedure and see if that changes the performance.
That's a great idea, I'll give it a shot but my gut feeling is that this has something to do with the TBW system. Has there been any known issues with this system?
 

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2000 E320
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131 Posts
I bought a new Bosch one from Autohaus, so I'm sure it's not the MAF.



That's a great idea, I'll give it a shot but my gut feeling is that this has something to do with the TBW system. Has there been any known issues with this system?
Gulfstream, I think we have the same situation. After changing MAF my car is a bit slugish sometimes when I accelerate, It even puts me in a limp mode when I floor it. Mine threw a code at me Throttle Valve Actuator. I did reset it and it hasn't come up yet again. Im waitin to see if the Check Engine is going to come up again, I usually don't floor my car, even if I want to somehow something blocks my acceleration.
 

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'68 280SE (w108), '72 280SE 3.5(w108), '88 560SEL(w126), '97 E50 (W210
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Just a shot in the dark, but if you haven't changed your fuel filter yet, you might want to.:) I've had the same symptoms lately, hesitation for a second or two when I floor the accelerator, then a sudden rush of speed. The behavior disappeared after I replaced my fuel filter. The old one (about a year old) was really dirty. Hope this helps.:)
 

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Dallas, Texas
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I absolutely concur with that statement. I just will not have the time to do this until the weekend. I'm pretty sure there will be no code though...I checked for stored codes a few weeks ago after changing a MAF sensor and there was nothing there other than the MAF codes. I'm pretty sure this is a problem with the throttle by wire setup...has there been any common or known problems with the TBW system?
What are MAF codes?

Electronic accelerator uses triple check to make sure all is good. Values from two internal potentiometers are compared. If there is more then 1 degree of throttle angle discrepancy it throws code and goes into limp home mode.

Third check is plausibility. Using internal map ME compares values of throttle angle, pedal value sensor and air flow. If values don't make sense it goes limp without the code. Typical cause of such situation would be plugged up air filter, restricted cats, low fuel pressure and unresponsive MAF.

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1998 E320
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I had the same problem as you a while ago. There was something wrong with my catalytic converters. The more I tried accelerating, the slower it did. But when I lightly stepped on the gas, it would accelerate better. Because it was a problem for me getting onto the freeway, I brought it in to the dealership as soon as I could to have it fixed. After replacing the cats, my car was back to normal again
 

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2001 E430, 2015 GLK350
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Discussion Starter #11
Finally Found The Fix!!

I know this is an ancient post but I finally found the problem after 4 years. It was the accelerator pedal sensor. I bought a new one for $125 and the problem is solved. It's located above the L/H fender by the brake master cylinder and takes about 5 minutes to change. P/N is 012-542-33-17. The funny thing is that the replacement part was made by Hella in Germany and it had the MB logos dremeled off, so it was an OEM part. So, if your car goes into limp mode when you floor it but otherwise drives normally this is your problem.
 
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