JackStraw

When I let up on the pedal after giving the car some gas, there is a transient gurgling sound from the exhaust before the resumption of the normal idling sound. I expect increased engine growl when I step on the gas, but not the gurgling sounds when I take my foot off. Is this normal?

A-Train

Yes, it is normal and will be most noticeable within the first few minutes of startup.

- A-Train

sillydriver

I get the same sound on my SL600 too. I’ve also wondered what it is. Maybe the turbocharger compressors stalling as they suck air with the throttle closed.

JackStraw

Thanks guys. sillydriver, was there any change in the exhaust sound after you made the Renntech modifications?

sillydriver

Not that I recall. Obviously, there was a change after mounting a Brabus exhaust. The gurgling sound has been pretty consistent all along. My hunch is that the gurgling is coming from under the hood: the intake side of the engine rather than the exhaust. Since it occurs just after closing the throttle I figured it was the still-spinning turbo compressors reacting against the sudden restriction of airflow. However, this is just my guess. I’d love to hear from someone who understands turbo engines better than I.

NooLimits

I was talking to a sales person and he said it sounds better when the engine has been on for over 5 minutes. If you do it to many times when you start your car, black smog will come out, and yes I have seen it happen.

miroj

The change in sound is mostly the equalisation in air pressure and lean combustion.