mmcfearin

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?

Plutoe

How old are you wires?? Do you have live data capability on your scanner??

MASTERBENZ

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

mmcfearin

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.

Plutoe

Although thoughtful, fuel pressure testing is not easy without the actual values and tools for the locations to be tested.

I would at least start to test the condition of the wires. However I do not have the values. Get a new one and check it's value. Rail and injector fuel pressure issues will normally produce faults. I would also check my coolant sensor----use your AC value test to check that! Just don't get suckered in to a new MAF!!

erashid

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.