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Discussion Starter #1
Yes I know this is the w126 forum but as many of you know I own a w208 CLK 430 too. I have been having what I suspect is ECU or TCU issues . When I reset the computer there car goes like a Ferrari for 500km then starts to bog on acceleration. It will rev to 3000 but doesn't feel like its accellerating like it should and it will bog under full throttle.

I have reset the ECU, changed fuel filter... This issue only arrises when the computer has completed it's learning stage.

Is there a way to permanently keep the car in learning default mode? Can a used ECU be hacked to work in your car?
 

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Discussion Starter #4 (Edited)
sorry I am dumb I don't have a check engine light unless i really floor it while it's bogging
500km after the reset it will run weaker and really hesitate on acceleration not to mention refuse to kick down. Stutter stutter stutter high revs are not met with equal acceleration
 

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Check on the W210 forums. A couple of E55 owners discuss a similar situation. I would also check your air mass sensor, it may be telling the computer to lean the mixture. I have a 1997 E420 which has the M119 engine so this may not apply, but for me I had a similar issue where a huge vacuum line that goes to the air mass sensor had rotted away and the car felt anemic. Once I replaced the line, the car ran like a scalded cat.

No CEL, I was tinkering around that area and found the line in that condition.
 

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I had something similiar with a R170. Floored it, sped up fast, and then it bogged down. It turned out to be the MAF. I code a CEL light though. It might be worth the time to remove the MAF insert and clean it with CRC mass air flow sensor cleaner. I am assuming you have the original MAF in there right now and not an ebay cheapee. It wont hurt anything to clean the MAF but it seems like it would kick a code.
 

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Discussion Starter #9
Nope they switched the MAF and it cost me $600 only to find out 500km later it was back to zero :-(
At one point the MB Star diagnosis said 2 coils were acting up, but when ever I do the reset it runs like charm.
 

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The coils should kick a misfire code. Any chance your CEL is not working? If you have an OBDII scanner, you can pull pending codes as well.
I think that he's going into the system using the MB diagnostic ports so he's getting a lot more detail then OBDII would read.

Maybe also worth looking at what your 02 sensors are telling the computer.
 

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Discussion Starter #12
I just bought a reader, it's getting no codes yet because I reset the ECU by detaching the battery but sure as sh!t it will act up in a week or so.
 
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