My 1992 Mercedes 600sel v12 has 2 cylinders misfiring causing a rough idle.
Almost everything has been checked and we are running out of ideas. We put in new spark plug wires, new injectors,new spark plugs, checked all the grounds, the air flow censor, etc.

Does anyone have any ideas?

Thanks

 

Are u sure ur getting a strong spark to all cylinders?

 

How did you determine that two cylinders were misfiring? Do you know which ones they are?

Do you have a multimeter?

 

Spark is a good question, I wonder about a bad coil pack.

 

Spark is good (that was our first thought), 3 and 10 cylinder are misfiring. The car was put on a tester for codes and the compression has been checked.
Thanks for the input so far...

 

Were there NO CHANGES AT ALL before and after you installed all those parts?

 

Yes, the car got a little better after each new part was installed, however, it is still running rough. We our hoping it isn't anything internal, such as piston rings, but we are out of options.

 

I guess I should have asked a different way. Were 3 and 10 misfiring before and after the plug and wire changes?

These plug wires are overly sensitive, IMO. I broke 3 or 4 when I changed plugs on mine. If you have a multimeter you can check the wires for 3 and 10 for resistance.

You can swap the coil packs for 3 and 10 to see if the misfiring moves with them. I'm assuming there are separate coil packs.

 

I HAD A 92 600 ALSO
HAD LEAKS AROUND INTAKE U CAN CHECK WITH ETHER TO SEE IF RPM CHANGES
INJECTOR HARNESS HAD SHORTS AND FINALLY THE MASS AIRFLOW WIRING HAD SHORTS
THE INSULATION MB USED ORIGINALLY IN THAT CAR WAS UNABLE TO TAKE THE HEAT

 

IF YOU DO GET IT RUNNING WELL AGAIN I HAVE A SET OF POWER CHIPS THAT RAISE THE HP UP TO 450
LET ME KNOW IF YOU HAVE ANY INTEREST