'94 E320t Problems - Where Do I Start? - PeachParts Mercedes-Benz Forum

latief · #1 05-20-2010, 10:20 AM

Just to be sure, cut a small bit of insulation in the channel the holds the wiring going into the coil area. that is the area most-likely to be affected if the wiring has not been changed. if you see crumbled wiring insulation inside, then you will need a new harness.

the smaller wires near the oil filter are for the lower wiring harness. not-essential to engine performance, and you could rebuild your own easily....

good luck !

daddi · #2 05-20-2010, 09:04 PM

HARNESS

RobertFini · #3 06-26-2010, 01:48 PM

Okay, so I finally got around to checking the new codes after clearing the old ones more than a month ago - good call latief!

The only codes that came back are #5 on the DM (EGR faulty) and #13 on pin 8 (O2 control system operating at rich or lean limit). So it looks like my problem is in the EGR system.

I'll do a forum search and see what turns up, but if anyone has any suggestions in the mean time let's hear them!

Best Regards,
Rob

RobertFini · #4 08-04-2010, 09:53 PM

I must give enormous credit to Arthur Dalton for helping me through this, with innumerable private posts back and forth - thank you for your patience, Arthur.

The old plugs were the proper Bosch F8DC4 units, and while they had obviously seen better days, they weren't in terrible shape so I cleaned, re-gapped and reinstalled them. The car ran very well, much better than before, but there was still a hesitation and surging under full throttle.

I had cleared all the codes and decided to ride it out for a while to see if any codes came back and whether the drivability improved. They did and it didn't, in fact the drivability deteriorated to the point where the car was chugging and missing and making me so disgusted that I must admit that I harbored thoughts of switching to a Toyota (not really, but almost) and continuously cursed myself for violating my own Prime Directive about nothing being as expensive as a cheap Mercedes, so I decided to try replacing the plugs as a "what could it hurt" step while I prepared myself for having to get deeper into this problem.

After a futile search for another set of the Bosch F8DC4 plugs, Arthur advised that some guys have had success with NGK BP5ES plugs, so I placed an order for a set down at my local NAPA and waited for them to arrive. Finally, they showed up and when I tried to install them, I found that they could not be installed because they require a 13/16" socket that won't fit down into the plug tube.

Drats - foiled again!

After some more research, Arthur forwarded to me a copy of the NGK part number decoder and we identified the part number for the 5/8" socket configuration: the BCP5ES.

Another wait while my local NAPA ordered the new ones, and when they finally arrived I gapped and installed them and it worked like you wouldn't believe! The car now runs like I knew it should, pulling like a freight train with nary a stumble or a cough all the way out to redline under full throttle. The kinship to my C36AMG is very clear, once again.

Who woulda thunk all it would take is a $12 set of plugs?!?

Thank you , Arthur!!!

Best Regards,
Rob