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Gas is new and i only use chevron 91.
i just pulled apart the car again.... swapped o2 sensors.
no change, stil right side bank shuts down. I would have thought it should switch if the right one was bad. Im talking about the pre cat o2 sensor. I left the air filters and intercoolers disconnected and still the same. I hit all the wires and the plugs that i could get to. No difference. The car does seem to run a little longer on 12 when the secondary air pump is running but it still shuts down when it gets to idleing with it running. Still no new codes, just immediately p300-306.
Well i would be lying if i didnt wish i had a 3rd one laying around. I was reading about fcpeuro on some forums saying they will return it if it doesnt solve your problem. I also found this awesome writeup on the m275. Its too big to attach but i bet if you search it you can find it. I think anyone with this engine should at least read it once.
its called "m275 initial training". Ill update with a link if i can find it again.
just put the car back together still same issue. I moved my car and noticed there was a good amount of abc fluid. Looks like my abc pump is out now too. Its leaking around the rear seal. Is it possible my pump was straining the motor and causing the misfire? I was having abc issues before this misfire started. I really am at a loss here. I cant even drive this thing to trade it in. Looks great but man im over it.
Well i would be lying if i didnt wish i had a 3rd one laying around. I was reading about fcpeuro on some forums saying they will return it if it doesnt solve your problem. I also found this awesome writeup on the m275. Its too big to attach but i bet if you search it you can find it. I think anyone with this engine should at least read it once.
its called "m275 initial training". Ill update with a link if i can find it again.
SL55, Opel GT, 70 LT-1, BMW 745 turbo, MRoadster, 49 Stude truck, 69 Z/28, Ferrari project
I don't have near as much experience with MB as Nick and many of the other guys on this board. It is sometimes really difficult to diagnose an electrical problem even with the car in front of you, and almost impossible from long distance.
I believe you have eliminated the O2 sensors by swapping from side to side. Also believe you have eliminated the coils and the plugs. You do have something going for you though, in that you can get it to repeat, apparently either idling down (even in park or nuetral, or by dropping it into drive). Because one bank quits either way (letting it idle down OR dropping it in gear). When I first read that one bank went dead when you put it into drive, I was thinking you might have a bad electrical connection, and that the slight torquing of the engine made that bad connection disconnect for a second. However, then you said it does it just letting it idle down. I think that eliminates the torquing theory, and at least in my mind, may eliminate the poor connection theory.
I can only see two things: 1. The VT module is bad, or, 2. The VT module is not getting an adequate votage signal at very low rpm. I would check your actual voltage upon start up, keep the volt meter on it while it idles down and see if it drops. A week alternator output at low rpm can wreak havoc on things that rely on a very constant voltage input.
Assuming that the voltage output from the alternator remains good at low rpm, I would try another VT, as others have suggested.
After this much work on the ignition system, I would try something else, just to ease some doubts. I have a mechanic's stethoscope - a listening device that has a long slender metal rod as the sensing probe that feeds sounds and vibrations into tubes leading to earpieces. Totally non-electronic, just a stethoscope that is optimized for mechanics. https://www.harborfreight.com/mechan...ope-63296.html
I have never even seen a Benz V-12 up close, so I don't know how practical this is...
With the engine running but misfiring, I would listen to each of the fuel injectors in turn. You can usually clearly hear the clicking of the injectors using the stethoscope. If all of the injectors click identically, you have just eliminated the fuel system as the problem. If some of the injectors are not clicking, your electrical or computer problem might be in the fuel system instead. Quick, easy, and either free or cheap, depending upon whether you have buy a $4 stethoscope from Harbor Freight.
Well i appreciate all the help but i had a talk with the wife and my s600 has to end. Even if i put the new transformer in i still have a bad abc pump. So there 2500 to 3k in parts. Plus my $6k earlier this year. I dont have time or space to work on this car at this point and im never going to trust it like i did. Goodbye s600 it was fun.
Im in stockton ca. Prob put it on craigslist for 6. Theres one for 13k in my area with more miles so i figureitshould go. That gives me even on the year. Lol
here is a pic
I got fingers crossed. Plus theres carmax here. And i can always split the parts with my buddy who wants to part it out. Ill give it a couple weeks and go from there. Check this salvaged one out here in california.
It took me years to completely eliminate misfiring from my first S600TT. It's now on 165k miles and I've been driving to work every day in winter, though not by choice. This what contributed to clean running:
New spark plugs - absolutely essential to have them gapped at 0.7 - 0.8mm.
New coil pack.
New lambda sensors.
New intake pressure sensors.
New intake temp sensors.
New lambda sensors.
Replace IC pump
Bleed IC system
T-bolt clamps on turbo pipes
Sad to see it go. I bet you can make a lot more money on the car parting it out, but that depends if you have the time or energy to do so.
I'm also dealing with non-stop misfires right now, it just never ends with these cars. These cars weren't exactly built with anything remotely close to a "good" ignition system, and that's pretty obvious at this point. The old M120 V12 was a much better engine.
You probably made a good choice in calling it quits. Hope everything works out at the end, and good luck!
I'd advise you guys to start with new OEM coils and transformers. I did that on my car, after doing plugs, and I have zero problems even tuned and me driving the car very hard all the time.
The system isn't the best, but it's not that complex, as long as the few major parts are working, it works.
Wouldnt there be a code of those were causing a misfire? Thats what the dealer said when i asked about that and cps.
I don't know who this is by your bbbc7 user name.... Have we talked ? You're 45 miles away...Want me to take a look at your before ;you get rid of it ?
Ok guys if you are still reading this thread its obvious i havent sold my s600 yet. I did end up ordering a new VT. No luck... gues 3rd times not the charm. So while i was in itf i decided to look at star, again. I found some values that ill post from the pressure sensors. I dont really know how to interpret them so hopefully someone here does. All of this pics are while the engine is running on all 12 cyl except the last one which shows values with engine off. Any ideas are greatly appreciated. I could just go replace a couple sensors which i might do anyway but they do obviously read with the change in pressure.
Those look normal. The specified value is wrong. The pressure sensor upstream of the TB shows ambient, which should be right around 1000 hPa, as shown. After the TB is in vacuum, so 300 hPa is normal as well at idle. There's no way they should both be 15psi of boost (1900 hPa) at idle. Only under load and high throttle do those specified values make sense. They are the same for idle and full load, probably an error in DAS.
Well darn i thought i was onto something. I switched the sensors and it came up about the same. Funny though my map sensor had oil in it. I wonder if the egr on the front of the left side of the engine can cause misfires. I doubt it but who knows.
02-22-2018, 08:57 PM
