[wojtech]

Hi everyone!

Does anyone know how the sound of the M-Perforamnce muffler in the M240iX F22 is controlled. There is no controlled electromechanical flap in the final silencer. In my car, there is always a very loud sound of the muffler after starting the engine, which lasts for 30 seconds and then fades away. This effect is the same with a cold and a warm engine. I wonder what changes this flow in the muffler. How is your cars?

Thanks!

[freakystyly]

That higher revving is the engine warming the catalytic converters. It always happens, even if the engine is already warm, unless you turn it off with coding. It doesn't have anything to do with the muffler side of the exhaust. As you know, the M-performance muffler doesn't have a flap, so control the noise with your right foot.

[aerobod]

The ECU tuning is such that the wastegate is open during cold start, this gives the increased noise due to the exhaust gases not being muffled by passing through the turbo.

[wojtech]

So only the open wastegate on the turbocharger is responsible for the much louder sound of the exhaust when the engine starts.

[aerobod]

Originally Posted by wojtech

So only the open wastegate on the turbocharger is responsible for the much louder sound of the exhaust when the engine starts.

Correct, when the MP exhaust is fitted (no flap). The open wastegate allows hot exhaust gases to reach the catalysts without losing too much heat warming up the turbo right away, so that initial emissions can be minimised. Aftermarket ECU tunes in some cases have the option to turn off this cold start behaviour.