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Discussion Starter #1
I've had this problem for quite a while now...

Car drives fine for the most part, but sometimes if I accelerate hard, the throttle will die. I have to pull over and restart the car in order to get throttle back.

It's gotten to the point that it pretty reliably happens, so I just don't accelerate hard, I just accelerate moderately from stops and on entrance ramps and don't bother to change lanes to pass a slow car when doing so would require accelerating hard.

But obviously, driving like that is nerve-wracking—never know if the car's gonna lose power and I'll have to stop and restart...

Any ideas what the issue might be?

I've taken it to two different non-dealer places. Once was, I guess, when the problem first began, the car didn't have any throttle at all after starting up; they replaced the throttle body, and so the car operated, but as described above. Second time, they replaced something else that I guess solved a check-engine light issue but didn't solve the loss-of-throttle issue. These weren't mercedes-specific garages/mechanics, so maybe that was unwise to go there?

Any thoughts?
 

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Administrator 2009 SLK 55 AMG/Founding Member 2006
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When indicating that "the throttle will die", are you saying that the engine stays running, but the no matter how the gas petal is pushed, the car does not respond?

Tim
 

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Discussion Starter #5

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Administrator 2009 SLK 55 AMG/Founding Member 2006
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put into near empty tank as it says. it needs to be near the fuel gauge/filter
then proceed to gas station and get the proper fillup of either 91 or 93 (super) per your manual

RESTORE
• Fuel efficiency
• Operation of broken fuel gauge sensors
• Lost power and improve drivability
CLEAN
• Sulfur corrosion from fuel gauge sensors
• Combustion chambers, intake valves, and ports
PREVENT
• Engine knocks and pings, spark plug fouling and cold start issues
• Harmful sulfur components from attacking sensitive electronic fuel sending units
PROTECT
• Fuel gauge from malfunctioning by coating all metal surfaces of the car's fuel system.

:D :D
 

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For me, the "techron" stuff is the best for what you are asking about. It is worth a try at least. The smaller cans say they treat 12 gallons, so if you have a full tank then put in two cans......I can't believe everyone doesn't do this at least every couple thousand miles or so. We have some pretty high performance engines and the junk gas we get now is just that.......junk......The next tank, do as advised above, put it in just as you fill up. MAKE THAT TANK AN ETHANOL FREE tank of the highest octane you can get. Pour in your two cans of "techron" and then try to keep your engine in the 3k to 4k range........Best is to get out on the interstate or a road where you can run at a high RPM with a constant speed for maybe 50 miles or so.......BURN that carbon out of the cylinder, piston, and valves and flush that stuff out of your intake......God bless......Dennis
 

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Administrator 2009 SLK 55 AMG/Founding Member 2006
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Administrator 2009 SLK 55 AMG/Founding Member 2006
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I have just the same problem with my 98 230, find out that it was the MAF sensor that was full of oil! I clean that with "MAF sensor cleaning spray" two times and now the car accelerate fine!

Hop it helps!

/Björn
 

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Bjorn,

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Discussion Starter #13
I have just the same problem with my 98 230, find out that it was the MAF sensor that was full of oil! I clean that with "MAF sensor cleaning spray" two times and now the car accelerate fine!

Hop it helps!

/Björn
Interesting. I'll give it a try. I actually have some MAF cleaner from several years ago. If that, or the Techron, fixes the problem, I'll be amazed. Did you have any check engine or other warning lights on on the console? (I do not) What made you think it might be the MAF sensor?
 

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No engine light on, and when I stop and start my car the car goes well to the first hard acceleration. And then the motor feels like 100hp. But cleaning the did wonders to it! :)

Interesting. I'll give it a try. I actually have some MAF cleaner from several years ago. If that, or the Techron, fixes the problem, I'll be amazed. Did you have any check engine or other warning lights on on the console? (I do not) What made you think it might be the MAF sensor?
 

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Discussion Starter #15
No engine light on, and when I stop and start my car the car goes well to the first hard acceleration. And then the motor feels like 100hp. But cleaning the did wonders to it! :)
Interesting. Thanks for the info. I will spray some cleaner on my MAF on Thursday.

For now, I've added the Techron as others have suggested, and we'll see if that helps... Had never heard of it before, but glad to know about it now.

Will give an update on the problem soon...
 

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Discussion Starter #16
Ok, so I haven't had an opportunity to check/clean the MAF sensor. But I did try the techron and over the past couple days, I've noticed a big difference. Most importantly, I can accelerate harder without experiencing a loss of power (though I'm still hesitant to really press it hard and put it to the test), I get fewer misfires/stutters/sputters/etc. This stuff is magical! How did I go so long without knowing about Techron? jbanks15 (and others who chimed in about techron), you are my hero(s)! :x :grin:
 

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Discussion Starter #17 (Edited)
Okay so today I was able to test it out a little more and I still got the throttle failure. Just took a little harder acceleration this time. Or maybe I'm just not remembering clearly and it's the same amount of acceleration as before, and I'm just suffering from the placebo effect. Turned off car, turned on again, and test drove a little more and was able to get it to happen again. So still have the problem. Any ideas folks?

(Also, I did clean the MAF sensor. Looked pretty darned clean to begin with. Wondering how yours would have gotten full of oil or other gunk. What's up with that?)
 

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From my experience, it sounds like it could be your gas pedal. The R170 has a problem with the gas pedal not sending the correct position of the pedal via the drive-by-wire system to the engine computer. This happens on cars that have seen a few miles. It happens on mine when I mash the pedal. It somehow knocks a connection loose inside the mechanism that won't restore itself until you restart the car. This makes you lose all power and it ends up feeling like a roller skate.

Replacing the gas pedal assembly will fix the issue. Of course, I don't know 100% if this is the case for your particular situation or not, but from what you described, it sounds like the same issue I had.

I bought a new pedal from parts.com but never got around to installing it, it's just sitting in the shrink wrap still... I really should get it put in.
 

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Discussion Starter #19
From my experience, it sounds like it could be your gas pedal. The R170 has a problem with the gas pedal not sending the correct position of the pedal via the drive-by-wire system to the engine computer. This happens on cars that have seen a few miles. It happens on mine when I mash the pedal. It somehow knocks a connection loose inside the mechanism that won't restore itself until you restart the car. This makes you lose all power and it ends up feeling like a roller skate.

Replacing the gas pedal assembly will fix the issue. Of course, I don't know 100% if this is the case for your particular situation or not, but from what you described, it sounds like the same issue I had.

I bought a new pedal from parts.com but never got around to installing it, it's just sitting in the shrink wrap still... I really should get it put in.
wow, that's interesting. how'd you learn that's the problem? how much does the assembly replacement cost?
 

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It may be your gas pedal or it could also be that one of the indies replaced your MAF for a non original part that tend to give problems .
Try removing the connector from the MAF and testing the car on a short run , if it's better you know you need a new , original MAF ....
 
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