I have had my SLK 230 for more than 2 years now, and it used to run perfect until two months ago when I parked it for two months (in a humid place).
since that time, when I step on the gas, the engine does not accelerate immediately as it used to be, and then slowly starts to rev. (without the powerful acceleration that it used to do). I have a 6-speed manual tranny, and the same thing happes every time i shifted (as soon as I take my foot off the accelerator pedal and back on it again, even if I put the gear on idle). This goes away when I turn off the engine and wait for a minute or two before starting it again. This problem started happening occasionally since coming from my 2-month vacation, and now it is happening almost always even when I re-start the engine. Note that the check-engine light never came on for this problem.
I read several threads about similar problems, I checked and cleaned the MAF sensor, but it made no difference. I also heard that the accelerator pedal might be the problem. Any advise is really appreciated. Pictures and some details to do it my self would be great as well.
Here is an update on how I solved this problem: At first, I took the advise of most bloggers who faces similar problem, and I changed the MAF sensor. The problem was not solved. Then I found out that the problem can also happen when the gas (accelerator) pedal sensor is not working properly. In the automatic transmission models, that sensor can be replaced by itself since it can be removed from the accelerator pedal and a part can be bought for it. In my case, I had a 6 speed transmission, and accelerator pedal in this case contains the sensor in its sealed harness. So I had to buy the whole accelerator pedal from the dealer (approximately $200). I changed it, and the problem disappeared.
Here, it is good to mention (as many of you may know) that accelerator pedal is not a mechanical one, it is in electrical one. This means that when the pedal is pushed, the sensor measures the pedal position and supplies the controller with the proper signal to control the throttle. So changing the accelerator pedal was a breeze. First, slide out the pin in the hinge to remove the upper part of the pedal. Then remove the cap covering the screw that holds the pedal base to the floor. Remove the nut and the washer, and slide the pedal downwards to disengage the top part of the pedal. Remove the sensor wire harness and the gas pedal will be fully detatched. Replace it with the new pedal, and do the same procedure backwards.
I hope this helps those of you who faced or may face similar problem.
A pity you did not get any replies to your original post. Great that you still came back and provided this feedback that others may make use of.
The pedal should have redundant position sensors and a fault code should appear (at SDS if not on the cluster) if the two are not giving the same info. Was your car diagnosed by SDS? If yes, I guess you did not get any error codes (at least stored codes should have existed).
I can faintly remember someone else reporting an issue with the accelerator pedal, probably on the W211 section that I follow more. But I don't remember any of the symptoms.
Well, unfortunately, I kept checking for replies for a while. Afterwards, I took the car to a dealership just to read any error codes that might exist (eventhough there were no warning lights of any sort lit). After hooking it up on the computer, they found code "P 2002" with the following description: B37 (Accelerator Pedal Sensor) Hall sensor2, a short circuit to ground/open circuit wiring (PO222).
Before then, I thought that the "check engine" light or similar dash lights would go on if the computer sensed any error codes, but now I know that not every error code triggers such lights. I was happy to see the car back to normal after replacing the gas pedal.
Thank you for your comments, and I hope some one would use the information posted on this thread.
Ron.
Last edited by ermq : 07-19-2008 at 11:43 AM.
Reason: correction
Linear Mode
