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.
sounds like the MAF. I've been experiencing the same problems. I've tried the CRC Cleaner and it worked for a bit but the check engine light came back about 2 weeks later. I have yet to replace the MAF.
Vehicle: 99 SLK230 18x8.5 all around, MAF Relocate & few other goodies (RIP); 81 CJ7 (Fully MOD)
Location: MD
Posts: 222
Similar to what I have a while back. I did the following just to find out what happened:
I replaced the fuel filter. It was dirty to begin with, so worth changing. Location of it is underneath the car, right in front of gas tank (do search on replacement of fuel filter).
I cleaned the MAF w/ cleaner.
Have AutoZone to read engine code (free), good way to find error code.
Do search on crank sensor here, maybe related (not sure).
Finally, I found out from dealer that it's a bad K40 module. Part is about $140 or you maybe able to fix it (do search on K40 relay).
This car is very easy to work with and you'll find good resources here to troubleshoot it. I drive the SLK more & harder now after that K40 replace and enjoying every bit of it Someone may have different input about your SLK.
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.
Could also be the fuel injectors. Get a can of seafoam from an auto parts store and dump that into the gas tank on about a 1/4 full gas tank. See if that helps, its about $5 and it may solve your problems. I had a project car of mine sit for about 6 months without being started and a half tank of gas in it. When I went to start it after those 6 months it was the same problem. Turned out to be that the fuel injectors were gummed up from the fuel sitting in the lines for so long. So emptied the tank, cleaned out the fuel injectors, new fuel filter, and fresh tank of premium gas, and everything was back to normal.
Someone may have different input about your SLK.
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