Polar Bear

Hello M275 owners. I have the M275 E55, but they are similar enough in design in operation where they both have their own quirks. I don't know even if their is a correct answer to this, but I have had an S600 pretty much in storage since around 2012-2013 timeframe, when it had 34k miles on it. It now has about 39k on it, and I decided to enjoy it this summer. It has experienced Cylinders 1-6 being dead one time before, that was resolved by repacking the respective coil pack and new plugs. Unfortunately, that didn't last but a few months and it began misfiring upon startup in the morning. After clearing the codes, turning the ignition off 10 seconds and retrying (sometimes 3-4 times it would start and run without issue the remainder of the day. I then started leaving a trickle charger on it at night and I noticed when the charger was on it, it was start and run smoothly on the first attempt. It did have the original battery in it, so I replaced both front and rear batteries. However now, 1-6 will not fire according to DAS (and the way the vehicle run) for anything. Almost immediately after start, the Check Engine light is illuminated and it throws P0300 and 301-306. I just did another spark plug change with MB plugs gapped at .7mm, and reinstalled the coil pack that I replaced last night, and the insulators looked new and there were no apparent issues. Before starting, the ME272 reported no faults (no sensors disconnected, etc.) and I was hoping this would at least help the situation but it made no difference. I can only assume the transformer is bad at this point. I checked the voltages going to the transformer and it is indeed getting the 13-14 volts, however I have not been able to check the voltage to the individual ignition coil packs yet. The driver side (left) has never had any misfires, but the left 1-6 is always the one that continues to report 1-6 misfiring. Also I have never had reports in DAS that only on or two cylinders are misfiring - its either the entire bank or none.

From what the MB bulletins say, the starting process can lower the voltage and cause ignition issues because of cranking resulting in similar symptoms.

I did remove the cover from the transformer, and the electric smell was extremely strong. I don't know if this is expected or not, but I can understand why with it being sealed so long and getting hot over the years. Can anyone thing of anything I could be missing besides checking the voltage on the individual coil packs, which I intend on doing?

Thanks for any help!

RaceHorse

What do you mean by " repacking" the coil? Typo for replacing? If so, with new or a "do it yourself" rebuild kit? I would strongly recommend a new MB from the dealer. It seems there has been more problems with the rebuilt ones, not worth wasting time on and off with the install. Also go with "stock plugs"/ stock gap, even with a tune, I've always run stock plugs. Factory are Bosch, if you don't want to buy from the dealer. The voltage regulator would be the next thing to replace. Thats the protocol.

Polar Bear

It was indeed a typo. I looked at my timestamp and states 4:04am, so I guess that explains it.

I have done exactly as you have stated - OEM Mercedes/NGK Iridium Spark Plugs gapped at .7mm, cleared all codes with DAS before start attempt, and each time the same 1-6 issue. The coil has less than 500 miles, and was purchased new at the dealer. Which reminds me - when I purchased it I was told it had a 2 year warranty, now I am hearing 1 year??? Anyway I don't think it is the coil but rather the ECI unit.

I think Clark from v12icpack has really done his homework on the ECI and combined with his experience makes a superior product than the OEM ECI. According to EPC, all ECI modues now are listed as "rebuilt" and there are no new ones available any longer. I think since it is narrowed down to this side and nothing has fixed it so far, the ECI has broken down (or possibly the wiring going from the N/91 to N/92/1. I am going to try an ECI I think as I want to enjoy the car this summer. I will let you know my experience if I order from Clark so others will know what to expect, but I feel good about it.

Thanks

nishboo

Did this get resolved?