Hello,

I have a 95 SL500 that was running good when I came home Thursday night. Friday afternoon when I started the car it seemed to be running rough, I just thought maybe it was cold from the temperature drop. As I drove there was and still is a noticeable drop in power as if I'm using 6 or even 4 cylinders. At one light I put it into neutral and put my foot on the accelerator to keep it idling. I removed the old F8DC4's and installed Platinum +4's and now my check engine light comes on. The car runs a little smoother but I still have no power, could this be a coil problem?

Any help is greatly appreciated.

Thanks Dave

I wonder if it could be a o2 sensor or clogged cat. converter ?

consider checking the diagnostic codes

The same problem happened in my 93 280E,I replaced the fuel filter and mixed one 500ml bottle of STP injector cleaner and filled up the fuel tank.After few days the problem completely solved.You can try this out.Good Luck.
MBZ.

I hate to be a wet blanket, but my 94 600Sl got very ill starting the exact way. Turned out to be failed wiring insullation on the harnesses to the electronic throttles. It started as power loss at high rpms cutting out like clogged fuel filter, then it went into limp in mode (check engine light, max rpm in gear 1400, etc.)

Detailed diagnostics said both electronic throttles bad $4300 + labor etx. I drove it howm , pulled them to see, and found the wires in th eharness cables were bare, sitting in a mush of duts that used to be the insullation.

Thanks for your replies. I read up on a good shop in the area and had to have my car towed in. It turned out that one ignition coil went bad and was causing the rough idle and loss of power. This workload was too much for the other coil which went and I guess fried the ignition control unit in the process. After having these parts replaced the car runs good except for a slight miss every now and then at idle. Maybe it's just a loose or bad plug wire.

Dbiad

Have the trouble codes checked if the "check engine" light is on. PO 0170 sounds like the problem you described. If so have the self adaptation checked to see if it's lean or rich. If lean you'll either have a vacuum leak or most likely a bad MAS sensor.

I'll bet your lingering problem is related to the platinum plugs you installed!!!!! But in BOSCH Copper plugs... the right ones that should be in there.
Do a search and you'll find out why the platinum's aren't good for Mercedes engines... I think little particles actually tend to break off, or something similar.

Good luck.

__________________
2006 E350 w/ 155k miles (Daily Driver)

Previous:
1993 300E 3.2L Sedan w/ close to about 300k miles
2003 E500 Brilliant Silver (Had 217k miles when totalled!)
1989 300E with 289,000 miles (had for <1 yr while in HI)
03 CLK 500 cabrio (Mom's)
2006 C230k (Dad's)
1999 S420 (Mom's/Dad's)
2000 C230k Sport sedans
2001 CLK320 Cabrio (Mom's)
1995 C280 My First Mercedes-Benz... (155k miles. EXCEPTIONAL AUTOMOBILE. Was Very hard to let go of!)