Cylinder 1 & 6 Not firing
 

Recently, I have noticed that my 1994 Mercedes E320 Sedan is idling and running very rough. It appeared to be missing. Upon further investigation I found out that Cylinder 1 & 6 were not firing at all. I thought that the coil on sparkplug 6 has turned bad, so I switched the coil 3 with coil 1 on sparkplug 2 which was working fine. After the switch I noticed the coil 3 in fact is fine but the replaced coil on sparkplug 6, which was working previously on sparkplug 2, is not working and spark plug on cylinder 1 and 6 are still not firing. I am stuck now. Could you please help me with the diagnoses from this point on so that I can detect the problem and replace the bad part/parts, if any, and be able to run this vehicle? How do I perform the tests to nail down the problem? If you have a wiring diagram for ignition, that would be a big help? Your assistance in this matter will be appreciated.

coil,the wiring to the coil can go bad too.

I also around a 150,000 miles just replace mine,cheap on ebay,use only bosch.

Has the wiring harness been replaced in this car? They are biodegradable and all will fail at some point.

Did you move the plug wires and connector boot? These can fail open causing a miss fire.

Use an ohm meter to check. I don't recall the spec but I think that 12,000 is about right.

Has wiring harness been replaced???

I just went through this. I'd suspect the plug wires. My 1&6 cylinder wire had no continuity. Replaced all wires and it runs smoooooth :-)

At 150K, I'd replace all of the coils, plugs, plug wires and coil connectors and you'll be good for another 150K. (Assuming you have the updated harness.) And surprise, I've found very good pricing on genuine Bosch parts on Amazon.com. For instance, $110 for the Benz coil and $55 for the same identical Bosch coil from Amazon.
Anziani
'97 CL600