misfire, black smoke, rich exhaust, hydrolock
Thread Starter
Senior Member
Joined: Jul 2011
Posts: 386
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Cl65 AMG
The engine runs as I said great, however hard acceleration causes hard misfires shutting down cylinders.
I have replaced the coils and plugs however the coils have 100,000 miles
on them. I'm guessing not many M275 engines have over 200K on them, so we might not know how long the new coils last ???
Maybe time for new coils ??? That is an expensive guess LOL. I'm hoping
maybe someone has some information about the coils ??? I know this old girl is getting close to the end of its useful life but I really LOVE it !!!
MBWorld Fanatic!
Joined: Jan 2011
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CL65
Are you getting misfires from both cylinder banks? If that's the case and and you have never changed your ignition control module, I'd start with that. If its just one bank and the new coils lasted 100K thats really not a bad thing. Good luck keeping the car going.
Thread Starter
Senior Member
Joined: Jul 2011
Posts: 386
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Cl65 AMG
V12icpack.com anyone seen their website ? seems they have some info that could be useful as well as some test services that make sense.
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07' E63
I'm a bit surprised no-one recommended you take out all the spark plugs, manually turn the Crankshaft CW to observe (1) if the engine turns at all and (2) which chamber(s) are filled with gas/coolant?. Be sure to have Shop towels handy as it will spit out the fluid from the spark plug hole. Once you determine which chamber(s) were filled with fluid, then use something to manually suck the rest of it out. If it's just gas, your problem is either the injector itself or your Cam Position Sensor Timing may be off and have have to be "relearned" via STAR/XENTRY. Furthermore, it could also be your Crank Position Sensor and it too must be relearned especially if it has been replaced. If it's not just gas in the chamber, then you have other problems (i.e.- Headbolts if mixed with coolant or piston rings if mixed with oil). If it's gas in more than one chamber, then it could possibly a problem with more than one injector or else it could be again either the Cam sensors needing to be relearned and/or the CPS. If it's gas, and you experienced hydrolock after shutting down due to shoddy grumbling idle, maybe also experiencing multiple misfires after doing Head/Intake work with the battery disconnected for several weeks/months, then it could be that the injector(s) remained open due to the Cam Sensors or the CPS not having been "relearned" say if you did any work on the head and hadn't started the car in a while and maybe your fuel rail was empty after having just been installed? If the Cam Sensors and /or CPS are NOT Learned beforehand, the ECU doesn't "know" what position the Cams/engine is in and thus, it may not tell the "injector" to open/close at the proper time, and can erroneously fill up the chambers with gas at ignition off! Whenever you can't turn it over after shut down, Take out the Spark Plugs first, then try to turn the Crankshaft Manually. This ensures you will limit further possible damage to the starter and quite possibly Piston rings, connecting rods etc. If Spark Plugs are all out and you can't turn the Crankshaft manually, then it could be possibly a valve that is erroneously open when one of the pistons is reaching TDC thus making it impossible to turn further. A $12 boroscope that wirelessly connects to an iPhone/iPad can be very useful here! A protruding valve is caused due to the timing of the Cams being wayyy off or a faulty valve seat or broken spring. If it's not a protruding valve, then it could be a bent connecting rod or worse! I hope this provides some edification to those of you who would otherwise be scratching their heads.
Last edited by E63007; Nov 10, 2018 at 10:08 AM.
