2003 SLK running issue
 

Greetings All.
I have a 2003 SLK 230. 85000 miles. It was running fine till the other day. I was pulling out of my driveway and the car stalled. It restarted however it was running rough. Then it would smooth out and run rough again. I connected my Maxi Check scan tool and found a P0340 code camshaft position sensor. Thinking I found the problem I replaced it. There was no change, and no codes were set after that part replacement.
So today I ran the car and the same lumpy idle. I will run smoothly then the idle will drop and almost stall. I did note that as it warmed up it seems to get worse. Start running rough then stall out. It does start back up. It will run very smoothly for a minute or two then start acting up.
I also checked the fuel pressure, it is a steady 50 Lbs. During the summer I replaced the K40 relay, filters, fluids, and spark plugs. The car has been wonderful to drive.
FUEL SYS A – CL-Fault
FUEL SYS B –
SHTFT1 – (-2.3)
LONGFT1 – (6.3)
O2S1 1 – (.775 V)
SHRTFT1 1 – (-3.9%)
O2S1 2 – (.0440 V )
SHTFT1 2 – (99.2%)

Can someone please help me to go in the right direction.

What is mileage? I'd be looking for vacuum leaks first.

I have a 2003 SLK 230. 85000 miles.
I have checked for vacuum leaks but I will check again.
Thank You

So today I ran the car and its running fine again. Went for a short ride and it started acting up. got home and just let it idle. (BTW I did try to post a video I cant seem to get it to work). It would shutter and almost stall then smooth out. The engine light came back on and it shows Cyl 1 and Cyl 2 misfire. No CPS P0340 code. I think the misfire codes are due to the poor running condition at the time. I have done nothing more at this time. Later today I will Reconnect my Maxi Check and monitor the MAF sensor I believe it should give a steady reading if working correctly. I checked for vacuum leaks. I found nothing.

Anthony Cerami
Author
Here is an update for today. VIDEO on my Youtube page https://www.youtube.com/watch?v=kuYK6u6Haj4 There is a noticeable rattle when accelerating and decelerating. The MAF is steady. You can also see the timing. on the scan tool.