so this is something that has been bugging me for quite some while now: compared to what I see on other people's maps, my normally aspirated VE figures seem to be significantly lower. I'm running a '03 VVT engine, flat-top intake header, stock 4-2-1 exhaust header attached to a 200 cell cat and a BBK catback silencer (absorption type, not reflecting type). My intake consists of an open cone filter (Vibrant), a 45° silicone elbow, some 2.5" aluminium piping and another 90° silicone elbow attached to the throttle body. I was wondering if my intake and/or air filter is causing to much restriction?
1 caveat: Due to altitude (500-600 m above sea level; 1640-1970 ft.) I never really see MAP readings above 94 kpa.
Today I was auto-tuning once again. This time around it was cooler (MAT 21-25° C) but rainy. (MAT correction was set to 100% to prevent interference, but I kept a close eye on MAT)
current VE and AFR tables VVT table was taken from DIYautotune.com
The VE on US-NBs goes up with MAP because they run static fuel pressure at the rail. So the higher the absolute pressure in the intake, the lower the pressure difference across the injector and therefore you get less fuel flow at the same opening time. MS doesn't correct for that by calculating reduced flow numbers, but by artificially increasing VE.
So if you're running static fuel pressure, something may be wrong with your engine. If you're running a return-style system, you're probably OK and there's nothing to worry about.
Edit: I read in another thread that European NBs have return-style fuel delivery. So you're probably OK.