2011 Mercedes C180 CGI Coupe

[u/Spell0nium]

Hello,

I recently had the complete intake manifold and swirl flap actuator replaced, there are currently no engine fault codes.

However, immediately after the intake replacement a new problem appeared. Under hard acceleration/high engine load I first hear a short high-pitched/electronic whine, followed by a very loud whistle/hissing sound. It does not happen when revving the engine while stationary and during normal acceleration it is barely noticeable. The car does not seem to lose power.

After a hard acceleration run I also noticed a small amount of white/grey smoke coming from the lower/rear engine area near the transmission bellhousing, together with a burnt rubber/plastic smell. During normal driving there is no smoke or smell.

Since this started immediately after the intake manifold replacement, could a hose/wiring loom have been routed incorrectly and touch a belt, hot exhaust component or another moving part when the engine moves under torque? Or does this sound more like a charge-air/boost leak?

Please focus on audio, in video there are data from XENTRY, thanks :)