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Old 01-09-2013, 04:55 AM   #9
roger 04 rt
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Joined: Nov 2011
Location: Massachusetts
Oddometer: 2,363
Originally Posted by Marki_GSA View Post
The GS range to my knowledge doesn't have a MAP/barometric sensor. If it does it is very well hidden and doesn't show on the GS911 software. When I get time/weather I will do a back to back run with a wide band sensors and post the logs. Don't get me wrong, I am not saying your in the realm of engine damage. You can quite easily find yourself with less than optimal running though. Usually quite the opposite from what you wanted from tuning options.
As I mentioned a couple posts ago, all R series motorcycles have a barometric sensor buried in the ECU and the GS-911 does report it, see the data from an R1150 below. Ambient air pressure is column F.

It's my opinion that changing the exhaust or intake changes the tuning dynamically of the air flow based on what I've read in numerous books. When an exhaust pulse leaves the engine a pocket of high pressure air leaves the cylinder when it hits a change in exhaust geometry (e.g. wider or narrower pipe, the catalytic converter, etc.) some of that pocket of air reflects and travels back to the exhaust valve, we're talking thousandths of a second here. If the reflected pulses pressure is high while the exhaust valve is still open, less air fills the cylinder when the intake opens. If the pressure from the reflectednpulse is low at that moment, more air goes in when the intake valve opens. These dynamic conditions change with RPM. When you put on an aftermarket exhaust or intake you may change these dynamics which BMW has carefully measured and accounted for the the VE (volumetric efficiency) also know as the Fuel table.

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