Quote:
Originally Posted by bishop4142
I thought if you had the engine dynamic mode set to sport plus the butterfly remained opened at all times
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Quote:
Originally Posted by bdoooh
I thought the same. If you switch from efficient to sport or sport+ the idle exhaust is louder.
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Quote:
Originally Posted by ss134
That's correct. Set engine response to Sport + and the valves stay open. Easy mod!!!
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This is not true.
They still close in sport+ mode.
Here is quote from interview with bmw m3/m4 acoustic engineer, Rainer Drees.
"For instance, if you select the COMFORT mode, the exhaust valves are fully closed in the lower revs ranges. If there is a greater load demand at higher engine speeds, they open up. When driving with a constant load in COMFORT mode, the valves generally remain closed to achieve a maximum level of everyday comfort over long distances.
In SPORT and SPORT PLUS modes, other engine characteristics are selected for controlling the exhaust valves. At lower gears, the exhaust valves are always open, while when higher gears are selected under constant driving conditions, they are closed; however, if the load conditions change accordingly, they open up in a flash. There are also ranges in which we have chosen to close the valves, for instance at low engine speeds in high gears. In these ranges, which are frequently selected in the automatic mode of the M DKG Drivelogic for driving at maximum efficiency, the exhaust tract in turbo engines would have a tendency to drone if there were no damping."