M104, 95 E320 "Missing" or Rough running

[Jim Villers]

I am now at a dead end.

While driving to breakfast this morning, the engine began "missing"; running very rough. After getting home, I pulled the plugs with hope of identifying the problem cylinder. All six plugs looked the same. I checked the resistance on the plug wires and "plug stub" and they were 1.5 to 2K ohms (within spec).

I then checked the fuse on the over voltage protection relay and it was good.

I also checked for malfunction codes; pin #8 (HFM-SFI) responded with one blink (no malfunction). The check engine light is not lit.

The wiring harness has been replace on this car.

The only other clue is that the exhaust smells rich.

Could this be an over voltage protection relay?

Anyone have other tests or ideas?