I'm not going to rule out the ignition system but it feels like it is highly unlikely to be the cause of the issue here. Any minor issues within the ignition system will become significantly worse with increased load. I'm not an expert, so I may be wrong. In my case, the misfire completely disappears when at full throttle.

I got my coil packs rebuilt from Clark, and I haven't heard of other people experiencing a similar issue using his coils. He also tests the coil packs on his own car before he ships them out, so I'm sure he would have noticed a slight miss at idle and done something about it before he sent them out to me. Again, I may be wrong, and this may be a one-time mistake, but I kind of doubt it given his track record. I think its something else.

This issue is definitely bugging me. My G wagon idles smoother currently. That really shouldn't be the case.

 

I agree the V-12 SHOULD idle as smooth as if not running. Mine do.

Just sharing my frustrating experience resolving a identical problem on my 95 Infiniti Q45, which has a very similar 'misfire detection' system---measuring the 'conduction' across the spark plug gap after combustion--just like this MBZ system.
That engine, after 14 years and 140K miles of fault free service---- would say 'detected misfire cyl x' and then shut off traction control, ABS, and Dynamic Stabilization systems saying communications with ECM not working right, and had a rough idle which vanished at just cracked off idle (the TPS switch just open). I changed the offending spark plug twice--no joy, swapped spark plug locations, changed ignition coil--3rd new Dealer sourced one tried worked. I had tried as you--changing everything, many different injector cleaners, air leak hunting--no injector swapping because 10+ hours to get to fuel injectors 'down in the valley' before finally finding a new ignition coil that worked right. Tech at Dealer where I finally took the car said he sees this quite often when the problem crops up--- swapping out new parts to find one(s) that work. Manufacturer (Nissan-Infiniti) says to replace all 8 ignition coils when the fault happens on a single cylinder. That is $1800!! Swapping coils proved the 'new coils' were not working right. I was unable to figure out why/what NEW OEM ignition coils would 'detect misfire' etc. I at least had the Dealer Tech keep swapping out the single NEW OEM coils until one WORKED. They returned the trial ones to stock as NEW saying they would likely work fine in another engine. Go figure?

In your situation with 3 adjacent cylinders offending, I suggest looking for something in common to them--manifold runner, vacuum line, injector power supply, branch in fuel rail (debris partially plugging line?), power transistor in the ignition coil assembly (talk with the guru who fixes the coils) do the 'propane' leak test to rule out intake leaks, snaking the test hose everywhere. I am assuming you have performed a compression test--the 'cranking' speed diagnostic test not spark plug removed one. Also check the O2 sensors out carefully--the injection times on each cylinder and trim values on each injector.

SOMETHING is not right--but what? Leaking cylinder head gasket? Broken head bolt? Plugged oil line to valve lifters" Plugged/not working right 'oil squirters' to underside of pistons? I am leaning more and more toward a weak power transistor or out of tolerance capacitor on the coil pack circuit board.
.

 

Clark likes to hunt down problems like this - if you’re able to take your car to Sacramento he may be able to help

 

TWC=three way converter = partially blocked/fouled catalytic converter

 

Alex, have you replaced the ignition transformer also?

 

Yeah the transformer is good. I even tested a different one and the same issue persisted.

I realized I'm making a very good point here in my own thread about how awful this coil pack design is. I'm having a misfire problem and cannot pinpoint it, and I cannot rule out the coil packs very easily because of their horrible interconnected design. If this car had a normal coil pack design, I could have swapped the misfiring cylinder's coils individually onto a different cylinder and see if the misfire code followed it. It's a very basic diagnosis method for tracking down stubborn misfires like this, but you cannot even do that on these cars! It facilitates even more guesswork and frustration.

Anyways, since every fuel injector isn't interconnected on a single printed circuit board and ran by an unnecessary complex system designed by hamsters, I can swap each individual fuel injector and see if the misfire follows to the other cylinders. If not, I'll give a shot at changing the front o2 sensors. After I try those and still have no luck, I'll send my coil pack back to Clark and see if he finds anything wrong it it. If the coil pack checks out fine, then I can only think of a small top-end mechanical issue or tiny (and hardly detectable) vacuum leak. If not any of those, I give up. I'll settle for a "smooth" V12 that idles like an old truck with a hole in the distributor.

The car consumes absolutely no coolant and a very minimal amount of oil, so I will rule out any "major" engine issues like bad head gaskets or broken head bolts.

 

I have great sympathy and empathy with your frustrating hunt for the trace idle misfires. I was never able to pin down and 'cure' the identical problem in my Infiniti Q45 --other than a great Dealer Tech swapping in/out a number of brand new coil assemblies until one worked. We could see the fuel short term 'trim' move back and forth a single unit in time with the roughness, but could not see any change in the injection time. We were not able to 'tune' the ECM 'map' to give that injector another millisecond of fuel injection at idle.
I wonder if you can 'tune' a slightly higher idle speed and smooth out that marvelous engine.?.

 

I agree the coil pack is a pain in the **** but Clark at V12icpack.com solved my misfire. Interestingly, my 2007 S600 has used two coil packs in 75K miles but both on the left side only. I also replaced the VT with one of Clark's. Very satisfied.

 

Hello Alex...not sure if you are still interested...but for anyone who is, John Cribb solved this issue for our Ferrari 12 cylinders. This MAY work, or some similar concept. See this link
https://www.ferrarilife.com/threads/...the-550.14000/

 

That is really interesting - if I had a twelve-cylinder, I would really investigate this set-up.

 

My previous message didn't get posted;

The coil pack that Mercedes is using has feedback on the ignition, which is not passive.
Therefore without any trickery, I think it's rather hard to change this to a regular coilpack setup.

 

Sure you can get lifetime replacements for the coilpack from Clark or fcp Euro. My question is for how long? I can't even find a place that sells the rubber insulator boots that go inside the coilpacks. Clark won't live forever and fcp Euro will eventually run out of stock. What happens then? We need something more universal because parts shortage will be an issue. Right now m y friend and I are building a 1995 nissan 240sx and 2 months ago we couldn't find an oil pan, New or used. It can't be that hard. I mean the coilpacks just send electric pulses to the spark plug which the sparks the engine. I'm sure normal coilpacks just have the transformer built in. Can't fault codes be removed through ecu tuning? Somebody please figure out how to run individual coilpacks on the m275 and save us from having to junk our car in the near future

 

I agree, but Clark is not the only one to repair these coil packs.

I've successfully repaired my voltage transformer and have the knowledge to repair a coil pack too.

 

Majority of us don't have the skill to desolder and re-solder chips or surface mounted resistors. We can all twist some wire together though. If someone could figure out how to wire up some individual coil packs that would be awesome. If not I might end up putting in a stand alone ecu. I mean for the price of one coilpack you could almost buy a stand alone ecu and wire in individual coil packs of your choosing

 

Not to jinx it, but my S600 goes through a coil pack or two about every 50K miles. If you are worried about parts shortage, you can ask Clark to sell you two coil packs now and not have to worry about it for another 5 - 7 years.

 

I am not junking my W221.

 

I believe I speak for most of us when I say I'd like to keep my s600 until I die. So what do I do 10-15 years from now? Parts shortage will be a very real issue for us in the near future. As I mentioned before, I can't even find those red rubber insulated boots that go into the coil pack. I was forced to reuse my old ones when I changed the spark plugs. I can't find them for sale anywhere. You would think something they tell you to change everytime you remove the coilpack would always be in stock but that's not the case. I actually got conned out of $80 from a fraudulent website that said they had it in stock. I am already feeling the pressure of the parts shortage problem. I am seriously considering buying a stand alone ecu and be done with it. Only thing holding me back is the can bus system. I can't afford $10,000 for the ecu that speeddriven used that has can bus communication. I'd probably go with haltech but what functions would I lose? That's my dilemma and also why I'd prefer is someone just figured out how to use individual coils.

 

When you buy one of Clark's coil packs, he equips them with new silicon inserts. I would never re-use an old insert. I think you are inviting an electrical short. I think the short answer to your problem is a parts car.

And I plan to keep my S600 for the next 600-700 years. I plan to pump the last gallon of petro chemical from the Earth.

 

Does somebody know or the motor control light automaticly turns off after fixing a issue whit coil packs or does it have to done manualy
mercedes don't want to work on my car after I did the coilpacks my self because I removed the intercooler pipes I wanted to bleed the coolant system

 

It'll clear itself after 3 cold starts and engine warmups

 

The answer is, it depends. If all you had was a CEL due to a bad coil pack and you replaced it with a known good coil pack, you should not need to erase the codes. If you are getting codes from another problem, or if you used a cheap coil pack from China; you need to rethink your desire to own a W221. Sorry to be the bearer of bad news.

 

Yes indeed I bought cheap Chinese "redone" coilpacks and cheap bosch o2 sensors chinese reverbisched voltage transmitter and original spark plugs tha car was running totaly better except I didn't run 3 warmups just 2 warmups, I just also changed the valve cover gasket As well , no matter what I will just rest off my life drive m275 I just wanted to see or it will work like this if it doesn't I just let it fix by mercedes ,I drove also 5k miles whit the broken coilpack whit fault code 3008 but only slow I drove car was fin it's was a c216 thanks for reply

 

dank je wel

 

My car is running better than ever after visiting Mercedes. I asked them to vacuum the intercooler system, but they said they couldn't because of an engine issue. They claimed the engine was running rough and couldn't vacuum the system due to the engine light. I told them the engine is in pristine condition and that the engine light was on because I hadn't cleared the fault code. I explained that I removed the coolant hose myself and went directly to them, so I was sure there was no overheating.

They said it was a lot of work and quoted me €700 to remove and refill all the coolant. However, after picking up the car, they probably realized I own six Mercedes and have spent over €20,000 on parts with them, so they ended up charging me only €150. Once I got home, I cleared the engine light and took the car on a 150-kilometer test drive, hitting 260 km/h (160 mph). It drives better than ever with two Chinese coil packs (€1,000), 24 OEM Mercedes spark plugs (€600), a Chinese voltage regulator (€400), four Bosch O2 sensors (€350), two OEM valve cover gaskets (€150), and a day of my time.

I'm also grateful to those who continue to buy their coil packs from Mercedes for €2,500 (the current price), keeping the brand strong. However, I prefer to invest in my own life rather than someone else's. Special thanks to Tim for the quick help. If any issues arise again, I'll report back to the forum. I just want fellow M275 owners to know that the engine does run, and there's nothing worse than having a non-running V12 in your garage—it's almost like having a cheating spouse or something!

 

Great news on the repair. I have to confess my suspicion on the Chinese parts but success is good! I routinely replace the coil packs every 40K miles but I purchased an upgraded Voltage Transformer from V12icPack.com to replace my OEM VT at 45K miles and now have 102K miles. Suggest you consider ABC filter and fluid change and auto trans oil and filter change especially if you do not know the history of the car. Good luck and keep us posted.