I've been working on a newly acquired E320 and so far it's taken quite a bit of time to diagnose a mis-fire condition. Here's where I'm at now and I'll give the history of what I've done in a second...

Ok:

• Turn key on... hear fuel pump pressure (pitch changes a little bit as it sits key on... not sure if that means anything)

• Start Car (starts easy)

• Car runs smooth for 3 seconds or so then begins mis-firing consistently.

So Far:

• OVP Relay had a bad fuse. Changed it drove it and read the codes. Got:

1. Code 4
2. Code 13 (Lambda Rich Limit)
3. Code 23 (Coil for 3 and 4 mis-firing)

Changed:

• 6 New Bosch F8DC4 Spark plugs (non resistor copper)
• 3 New under coil spring boots

Still misses. I really wonder if it's an electronic problem because it runs smooth for 3-4 seconds EVERY TIME and like clockwork resumes the miss.

I sort of thought fuel filter but it performs under high load (up hill floored). I wouldn't think that'd be possible if it wasn't supplying enough fuel to idle right.

So far I'm pretty stumped. I'll cut the wire harness wrap in a few spots just for a visual. But I don't know what else to check. I don't think a bad coil would let it run for 3 seconds and then cut out Every Time.

But of course... I don't know anything other than basic gasoline operation. I don't know squat about the Lamba system or how this engine runs (computer control) etc.

__________________
-E300d '99 350k
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-TDI Jetta '03 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
-300sd '80 300k
-7.3 Powerstroke Diesel 15P Van 500k+ miles
-190d '89 Non Turbo 2.5 5cyl 240k (my first MB)
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