S420 1995 running rich
 

Having problems with my new '95 S420, 177,000 miles, unknown prior maintenance. Engine light came on, started running rough, rich and with practically no power car stopped. Get it home, check the distributor caps, worn with massive arcing, don't believe they had ever been changed. Replaced both caps and rotors, cars idles nice again, engine light still on, still running very rich, strong gasoline smell from the exhaust. I check the LED/button code reader get codes 4,5,6,7, and 25. Clear each code individually restart engine four times after letting it idle for a couple minutes in between each start. No codes recur, after three days, however still running rich, no power at all. Any ideas?

Those codes are:
4 Air injection system faulty <--- broken vacuum lines??
5 Exhaust gas recirculation faulty <--- EGR sensor or line plugged?
6 Idle speed control faulty <--- could be ETA . .Menu#24??
7 Ignition system faulty <--- ditto above.
25 Knock sensors faulty

You can codes from my page, MENU#6 (Diag Module).

Check MENU#24 for ETA problems and how it starts. . . :rolleyes5

Bad coil
 

Good news, turned out all it needed was a coil for one side of the engine, replaced the coil runs perfectly!