rsmooth

Hello all!

I could use some help on troubleshooting this issue.

I have a 2015 C400 that I've been driving around for a while that has lost a good amount of power on acceleration. I suspect the turbos have stopped working since when I floor the gas pedal, the car accelerates very slowly from what I'm used to. I'm not seeing any other issues and the car does reach highway speeds, but it just feels as the turbos are not working. No check engine light or any other codes pending. Seems like this just one day happened as the car was running perfectly.

Here is what I've done and I don't recall if this issue occurred before or after these repairs I performed:

• Changed battery - I've heard that it's supposed to be programmed after it's been changed and I've also heard it's not a big deal if you don't have it programmed. I never programmed it after the change.
• Changed cabin filter under the hood and both air filters.
• Changed spark plugs.

I've been driving the car around in this state for a while now, but have a little time now and would like to fix this if I can and get the missing power back. Again, no check engine light or other codes pending and the car otherwise runs normally.

Thank you for any tips or suggestions that can help me solve this mystery.

TwoC400s

This issue started some time AFTER you changed the plugs?

As a free diagnostic step you could pull them and see what they look like. Google images is your friend on "reading spark plugs."

Your best bet is to get an OBD diagnostic tool that's capable of real-time logging of the sensors. Check your boost pressure, fuel trims, ignition retard, etc.

It is kinda weird you don't have a code, but sometimes these cars just don't throw them for low performance issues.

There are a myriad of sensors and control solenoids that could possibly be the culprit; you would be the first M276.8 motor I've heard of to have the turbos go bad.
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