I had just bought a slk230 (98) and i noticed if i excelerate fast my check motor light comes on, And it runs real rough i was wondering if any one knows what this could be ? I disconnect the battery for a few mins and the light stays off til i do it again ...

 

Hi if you read General Tech

SLK 230 hesitation - it may help (posted yesterday)

basically try cleaning the intake and breathers with electrical cleaning spray before spending a lot on parts and labour

Common problem with this model

I use Mobil 1 engine oil and run car with oil level a couple of milimeters below the max level to reduce the effect of oil mist in the intake system

 

too many things can result this like a stuck open egr valve.
but the weird thing is ur check engine light is not suppose to vanish after the disconnected battery. u need to scan ur car with the mercedes DAS scanner b4 u start buying senseless parts.

 

My 2000 s430 started misfiring and got so bad had to tow it. Turns out one whole bank of cylinders was misfiring (left side). Problem was a plugged catalytic converter (there is one converter for each side of the engine).

 

Post some codes