UPDATE: 3/9/10

Changed the plugs to F8DC4 Bosch copper non resistor and the springs under the coils. Here's what I notice now. Turn the key to on for a second, start, runs smooth for 3 or 4 seconds then resumes missing. It does this every time I repeat the procedure.

I just bought my first Gasoline powered Mercedes (94 E320). I got it for $200 thinking that if it's trash (has 200k on the clock) I can use the W124 parts for something eventually. Heck, my climate control unit is needing to be changed on the 87 and that alone would cost me half of that used.


Anyways, before I go gutting anything, this 320E is a nice car. I did a little bit of a search and I don't think I came to any conclusions. It seems like plugs, wires, coils, and harness are the main mis-fire culprits.

Here are my symptoms.

1. Rough lopey idle (obviously missing)
2. Unburnt Gasoline smell until the cat warms up. Then MAJOR rotten egg smell
3. Some white smoke (not sure if it is the unburnt gas hitting the cat or a bad head gasket)

Here is what I found so far:

• Autolite Spark Plugs (obviously someone has given this a 'tune up' a year or maybe couple years ago)
• Here's the weird part, I couldn't even see the spark plug in cylinder 3 and 4 they were so covered in carbon. It almost looked like the soot and semi burnt fuel had gotten past the spark plug.

So here's what I did:

• Cleaned the spark plug well out and cranked the engine over a little to blow out the soot (thick grainy soot and lots of it. Enough that initially I couldn't even get to the hex on the spark plug with my 16mm socket).
• Cleaned the connections up

Then I started the car and it ran smooth as a top. UNTIL... I put it in reverse for my test drive and then the miss came back. I figured, oh a little soot or something so I gave it a good incline Italian tuneup. Still missing. Put it in park and still missing.

I've done this twice and same result... good wire and plug clean up and runs smooth then misses.

Could it be that as soon as I put it in gear that it's not getting enough fuel or could being in gear effect something electrically with my spark? Or something else???

EDIT 03/03/10: Update, OVP Relay had a bad fuse. Changed it and the ABS light went off and check engine light came on. Codes read and posted later in this thread. Still misses regularly. Every so often it will smooth out but mostly missing. Codes cleared and we'll see which ones pop back up.

__________________
-E300d '99 350k
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-F250 '96 7.3
-Dodge Ram 12V
-E320 '95 200k
-E320 Wagon 1994 155k
-300d Turbo '87 187k miles
-E320 1994 200k
-300d Turbo '84 245k (sold to Dan62)
-300d Turbo '84 180k
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