W221 engine in a C217?
Thread Starter
Member
Joined: Sep 2015
Posts: 139
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From: Detroit area
2015 S550 Coupe; 2025 EQS 450 SUV
W221 engine in a C217?
I’ve got a weird one for you guys:
I was getting cylinder misfires on my 2015 S550 coupe (mostly cyl 8, a couple 1,2,6) to the point that the CEL came on. Took it to the dealer. They did a compression test. No mechanical issues. They determined it needed a software update?
And why did it need a software update? The mechanic saw some writing on the engine that said “2012 S550”. They think someone replaced the engine at some point. News to me. Didn’t flag on carfax (mostly serviced at dealers) or on dealer PPI, where they checked all dealer service records (out of state) and told me everything was well-maintained.
The software update “to match to factory spec” does seem to have fixed the misfires. No other gremlins, either.
Does this make any sense? An M278 engine from a 2012 W221 that works in a 2015 C217 or W222? And which needs 2015 factory software to run optimally? I thought they made tweaks to the engine and upped the HP on the W222 generation or maybe it really was all just software. I’d also imagine such a transplant would have all kinds of issues and would need custom work.
I was getting cylinder misfires on my 2015 S550 coupe (mostly cyl 8, a couple 1,2,6) to the point that the CEL came on. Took it to the dealer. They did a compression test. No mechanical issues. They determined it needed a software update?
And why did it need a software update? The mechanic saw some writing on the engine that said “2012 S550”. They think someone replaced the engine at some point. News to me. Didn’t flag on carfax (mostly serviced at dealers) or on dealer PPI, where they checked all dealer service records (out of state) and told me everything was well-maintained.
The software update “to match to factory spec” does seem to have fixed the misfires. No other gremlins, either.
Does this make any sense? An M278 engine from a 2012 W221 that works in a 2015 C217 or W222? And which needs 2015 factory software to run optimally? I thought they made tweaks to the engine and upped the HP on the W222 generation or maybe it really was all just software. I’d also imagine such a transplant would have all kinds of issues and would need custom work.
Junior Member
Joined: Jan 2022
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2005 CL600 (US model) & 2019 S450 Coupe (EU model)
If you have 2012 engine and assuming the chain was not upgraded to the post 2013, then you can verify that you have 2013 or earlier engine by removing your oil cap
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Joined: Nov 2010
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Cars
The 2011-17 are the same engine with a few tweaks. Software updates vary depending on what car the engine is in. The same engine in a CLS is different than the E and the S (W221) and W216. I wouldn’t think it would all of a sudden become incompatible after this long due to a software issue. I did take my 2012 CL550 and they did a complete computer update on all system but it didn’t change anything.
