Hi to all,

i came here hoping to get some help and maybe help others on the way.
ive got an 2008 C63 AMG that ive been owning for a couple of years now, i think ive driven 25000 to 30000KM on it since owning it.

im running into Misfire on mostly the rightbank, however everytime i read codes, its another coil,
also having sounds coming from the engine which isnt consistant.
ive checked O2 sensors (on the right bank they were darker coloured with carbon?!)
read live data/fault codes with Xentry diagnostic which most showed most values within specs.

below a long story with background info.
One year ago i drove back home and i stopped at my work to pick up someone, i left my work and at the very first corner i noticed the car started to idle rough and had a slight bit of power loss, on to the next intersection i needed to stop, and i started to smell an extreme lot of unburned fuel (like someone poured it straight from the can into the cars interior.
the car died on itself while idling,(probably because of the way to rich mixture). when i tried to crank the engine again it just gave a louder click noise, (dont think the crank turned alot) i heard this and straight stopped the engine to continue cranking, i knew the engine had locked (hydrolocked with fuel) the smell was so heavy probably the exhaust had fuel in it aswell
i towed the car back to my work parking space where i didnt wait to long, took the sparkplugs out of the engine to release stress, and Cyl 7 or/ and 8 had filled up fuel, when cranking the engine with no sparkplugs it sprayed fuel out these holes so bad, i left the sparkplugs out there for the weekend so the fuel could vaporize,. from this moment i started working on the car without starting it again.
i ordered new sparkplugs (just in case) and new Bosch Injectors, and started to replace these. when i unscrewed the first fuelrail screw i had the biggest luck that the mounting points just broke of the intake manifold, my intake manifold got the beautiful virus of magnesium corrossion, from this point i start to take the intake manifold off the engine and open it up finding also a cracked throttlebody plate, also measured piston height on all cylinders to make sure no conrod got bend, also with a camera no damaged was found, only to noticed everything looked clean with maybe just a but of carbon on the piston heads, all pretty decent for a 195.000KM engine

got myself a used good shape intake manifold, an RMT alloy TB plate, and starting to build everything back together, i left the foam cushions below the Intake manifold away as they already dissolved a bit but also look like they hold moist on the place the intake manifold got corrossion damage, (since i had the car on the lift i also replaced the engine mounts and obviously since fuel was in the engine i changed the oil and oil filter)
at first the engine and all started and runs normal from point of start, everything looked all fine, drove the car another 3000KM by guessing. when i starting to notice some knocking sound coming from the back of the engine, in which i cant point the exact location, this knocking was only when the car was real hot, after a long drive at idle speed, if you pushed the throttle with the smallest toe and raise the rpm by 20 rpm it already disappeared, knocking sound didnt became louder or stronger on higher RPM, so this gave me the idea the conrod and crank bearings should be fine., i however do kept driving the car and the knocking sound was not noticeble while just driving, only on stand still (this sound also disapeared lately as the outside temperature became colder im not sure if this has anything to do with each other),i did check the knocking sound on a lift from below the car, if i have to guess the sound comes from somewhere arround the torque converter/flexplate.

i later on noticed the car started to Misfire on High RPMs, so when you hit the power and came arround 6000RPM, it then just kills the power, and the CEL/MIL/Engine light starts blinking, i then instantly come of the throttle and find a safe space to stop the car, you feel the engine shaking from misfire and having a few cylinders deactivated, ignition off and on again and the car runs fine on 8cyl again. (when reading fault codes it just shows various cylinders, one time its 3 5 7, the other time is 2 7 8 and the next time its 4 2 7, i do however had cyl 3 on it a few times, decided to replace that coil just as a check and i havent got a code on cyl 3 anymore, after googling a few days i found someone writing something about bad O2 sensors an maybe a failing Catalyst, which gave me the though, could my exhaust fail me,( when i bought my car it was straightpiped, but to have it pass through emission checks every year it needed to have a Catalyst converter in it, so i let an exhaust company put 200Cel Cats in the oem empty Cat housings)

last week i replaced the exhaust with an OEM version just to check if this changes anything, i noticed the Right bank the O2 sensors where black with Carbon (the right bank is also the most common to give me Misfire error codes) the left bank o2 sensors looked way better (normal with just a tiny bit carbon) also did the right bank exhaust had a bit more blueish metal colour, as that side of the exhaust became more hot then the left bank.
so now another thing start to act up, or it has to do something with the knocking sound, i feel that car starts to vibrate heavy at certain rpm points, while driving or in neutral/park, when you bring the rpm up from idle, the car starts to vibrate at 1700RPM, then disapears at 1800, and the vibration comes back at 2250 in a bit heavier form and goes away again at 2750 rpm. over the last 2 days this vibration starts to become heavier, so im going to stop driving the car.
when i tried to start the car today, it for the very first time just let the starter spin without taking the flywheel/flexplate with it,

when driving the car, on some pulls there is some strange loud and rough intake sound a sudden open DTM intake arround 2/3000RPM and it goes away above.. also this is inconsistant.
some pics and vids attached for someone who wants to check them.

thanks for any thoughts and advises.

This could be a timing chain issue and the plastic timing chain guards then throwing everything off. When its a camshaft position sensor issue your timing isn't correct but because it didn't show this code earlier, its something deeper. You also probably have severely worn down camshaft lobes. You need to open up the engine valve covers and start with an detailed preliminary inspection. No other way around it. Just reading codes and clearing codes wont help...

Hi,
thank you for replying,
im not getting codes on the crankshaft position sensor.
ive changed headbolts 5 years ago lets say 20.000km ago, ( damn time flies…) everything looked fine then, but i just supprised myself when searching back how much i already drove this car.

i will check under the valve covers again, do a compression test on all 8 cyl.
and probably also lift the car and remove the transmission to replace the torque converter because of the noise coming from there

So i started working on my car last Friday, i run the car and pulled coilpack connectors one by one to listen if the engine knock became noticable

while doing this i concluded that i dont think any issue comes from here, also the sound isnt that consistent, and being with my head over the valve
covers, sound is absolutely not coming from there.

i decided to take the risk and starting to take the gearbox out of the car, i already ordered a used torque converter since i think the sound comes from here, also noticed some shuddering

so exhaust off, propellershaft out, gearbox oil out, and gearbox off, i instantly noticed a major damaged flywheel or flexplate.
i think i found the problem for all my issues since the Crankshaft Position Sensor is also here, i wouldnt be suprised my misfire errors also comes from this.