Mt 1997 E420 is running poorly, rough and loss of power, also poor fuel millage and the smell of raw fuel in the exhaust. I started having these problems at 154K so I had the 150K work done at an indy. Plugs, boots, and all 4 O2 sensors replaced.

I am at 168K now and all problems have returned. Codes show cylinder 2,3, and 8 missfire, multiple missfires, and rear back O2 sensor failure.

I I found all this returning odd but I did use an indy I had never used before, generally I do all my own work after warrenty but got lazzy. So I pulled and replaced all plugs (copper ones spaced correctly now) the indy had installed platnum plugs in an amazing aray of poor gap settings. I also replaced the 3 boots. The O2 sensor erros I figured was just do to raw fual because of the missfires so I have not replaced it yet.

Unfortunatly this didn't correct anything so I went ahead and replaced all 3 ignition coils. This also has not solved anything. I can't see an O2 sensor causing all this and while I didn't get a code for it this seams to me the next thing to replace is the MAF. Ideas?

 

Check fuel pressure...sound like a fuel problem to me!

 

Unfortunatly I don't have live capabilities on my scanner, I am looking at finding a new scanner preferable one that links to a laptop.

I have not thought of fuel presure issues, is there a test I can do for that?

The wires to the coils are original.

Thanks for your time guys.

 

I had the same issue spent over $800 trying to fix at indy's with no luck to finally be the wires.try taking one of the wires on a cylinder that is not complaining with one that does; and see if the issue follows.