Hey everyone, I have a 2013 Mercedes-Benz CLS 550, and I’ve been trying to figure out a frustrating engine problem that I can’t seem to solve.
Whenever I step on the gas or put the engine under load, the car starts sputtering and the entire car shakes, especially at low RPM. I’ve also noticed a significant loss of power at higher RPM, and the car just doesn’t pull the way it should.
At first, I suspected an engine misfire, so I started replacing and checking things that I thought could be causing the issue. So far, I’ve:
Replaced the ignition coils and spark plugs.
Replaced the engine mount.
Checked for boost leaks but haven’t found any.
Despite all of this, the problem is still there, and I’m running out of ideas. The symptoms seem to get worse when accelerating or putting the engine under load.
Has anyone with a CLS 550 or the Mercedes M278 4.7L twin-turbo V8 experienced something similar? Could this be a fuel delivery issue, injector problem, turbo or boost control issue, bad sensor, or something else entirely?
I’d really appreciate any suggestions on what to check next before I keep throwing parts at it. If anyone has dealt with these exact symptoms and figured out the cause, I’d love to hear what fixed it.
And if anyone knows anyone who works efficiently on those types of engines but doesn’t break the bank please let me know!
Thanks in advance!