RomRaider

Hello,

I'm doing some research how is calculated and used value Secondary Air Flow (in logger) . I found its subroutines in ECU disassembly and when playing with pressure values on real engine I have got weird results:

Real atmospheric pressure: 100kPa

case 1:
SAS idle pressure: 110kPa
-SAS error P2444 because air pressure in SAS piping is 6.5kPa higher than atmo pressure
no reason to monitor rest.

case 2:
SAS idle pressure 70kPa - so low to avoid case 1 problem at high latitudes
SAS fan on valve closed pressure: 120kPa - same as original working condition
SAS fan on, valve open pressure: 113kPa - same as original working condition
SAS air flow: 0g/s ! WHY? obivously after 2 drive cycles it throws error P2441 valve stuck closed because there is no flow detected by ECU

case 3:
SAS idle pressure 92kPa - so low to avoid case 1 problem at high latitudes
SAS fan on valve closed pressure: 127kPa
SAS fan on, valve open pressure: 116kPa
SAS air flow: 0g/s ! WHY? obivously after 2 drive cycles it throws error P2441 valve stuck closed because there is no flow detected by ECU

case 4:
SAS idle pressure 92kPa - so low to avoid case 1 problem at high latitudes
SAS fan on valve closed pressure: 127kPa
SAS fan on, valve open pressure: 108kPa lower than case 3 to make difference between idle pressure and "flowing" pressure approx same as in original condition
SAS air flow: 5,4g/s ! Well this is OK, but how is calculated?

case 5:
SAS idle pressure 100kPa - same at actual atmo
SAS fan on valve closed pressure: 120kPa - same as original working condition
SAS fan on, valve open pressure: 113kPa - same as original working condition
SAS air flow: 8g/s ! Original flow with complete workign SAS but how is calculated?

I know how and where is used SAS valve pressure in NA and turbo but what I'm looking at moment is how is calculated flow value and for what is used (besides evaluation of SAS functionality) .

If anybody have some idea I will be grateful.

From ECU code I have about 6 subroutines which are referencing flow RAM address and I need to analyze them, maybe then I will have more info.