I have a 2001 SLK 320 with 61K which I purchased several months ago with a check engine light lit. The owner told me that is normal, and will need to be reset at some point but was not a problem. The car has been running great until this past week. The car is hard to start and back fires until I stop the car, shut it off, and restart. The car then runs great. I also noticed that the lit check engine light flashes occasionally when this happens. I know I need to get it in for service, but does anyone know what would cause this rough running? It is like something gets reset after I turn it off and restart. During the latest cold spell, I would think it would be the opposite. I would appreciate any suggestions.

Thanks,

Jeff

 

Get the OBD codes read then we can advise what is up.

If the Check Engine Light CEL is ON there is a problem. That's what it means.

Stuart

 

Dumb question for a novice at this. How do I obtain the OBD codes?

 

I had a similar problem. Every time the Check Engine light was reset, it would come back on. Engine started running rough at start up. Took it to several shops trying to get it fixed. Turned out that a metal chip was caught between the engine block and the manifold. Over time the metal chip worked its way into the cyliner cause water to enter the cylinder. Not enough to smoke but enough to caus ethe engine to misfire especially during start up. Ended having the engine block planed off to remove the score that was causing the water leak.

 

Not a dumb question.
Sorry different people have different understanding dependent upon experiebce.
Since your car is a 320 it has OBD On Board Diagnostics with the 16pin trapezoidal connector.
The socket is located adjacent to the bonnet pull behind a flap.
Any OBD II scanner can access the codes so any garage should be able to help or you can buy yourself a scanner 50 to 2000USD dependent upon functioanlity etc.
Codes will look like P0170. These codes identify cause of problem...Not what is wrong. Experience is required to convert the code definition into what has gone wrong.
CEL ON = Problem which may or maynot be noticeable to the driver.
The scanner can reset the light (turn it off) but if the fault remains it will come back on again. Simple really!
Get the codes and we will try to help further.
The codes are a step towards the solution and sometimes aren't very helpful but its the first stepo.
The other gut who posted had his CEL come on due to misfire. Misfire could be caused by 1001 things (I exaggerate a little). Turned out to be a head gasket problem (unusual) in that instance.
Stuart

 

Thanks for the additional information. Sounds like it is time to get into a shop.

Jeff

 

If you have an AutoZone nearby, they will check your OBD code free. Most shops charge 1/2 to 1 hour labor.