roger 04 rt
New member
At 4000 rpm, small throttle angles, the 1150 appears to be open loop. In the higher gears because you're going faster, the engine has to produce more power and your throttle is more open. At higher throttle angles the Motronic applies closed loop control.
I've spoken to the guys at PC and asked them about the chart below which shows where they believe the Motronic is closed and open loop. According to them, it is their understanding of it but they can't say for certain that it is accurate. The dark area is closed loop and the white area is open loop.
Why BMW has designated the various areas open and closed is harder to work out but it is either because closed loop is unreliable at those RPMs and throttle angles, or because they always want either leaner or richer operating conditions that closed loop would allow.
Back when I began this project it was partly because when shifting up in the low gears, I experienced slight roughness when the engine was warmed up, right at the "top" of the shift. It now appears that this is an area of leaner open loop operation. By reducing lambda with the Wideband we're also reducing lambda in these open loop areas.
I've spoken to the guys at PC and asked them about the chart below which shows where they believe the Motronic is closed and open loop. According to them, it is their understanding of it but they can't say for certain that it is accurate. The dark area is closed loop and the white area is open loop.
Why BMW has designated the various areas open and closed is harder to work out but it is either because closed loop is unreliable at those RPMs and throttle angles, or because they always want either leaner or richer operating conditions that closed loop would allow.
Back when I began this project it was partly because when shifting up in the low gears, I experienced slight roughness when the engine was warmed up, right at the "top" of the shift. It now appears that this is an area of leaner open loop operation. By reducing lambda with the Wideband we're also reducing lambda in these open loop areas.