The VPC was a speed density system and you normally run standalone systems like the AEM EMS in speed density mode.
MAF/MAS systems know how much air is actually going into the motor. They are very popular with car manufacturers, because if the motor degrades over time or there is some problem with one thing or another, then the ECU can compensate on it's own quite easy. When there is a boost leak on factory turbo car, they will run richer, which can save a motor. Also, they can compensate for mods done to the car quite well.
Speed density systems only know air pressure, air temp, and sometimes barometric pressure. So they don't compensate for changes in the motor from mods at all. If you do something that makes more power, you go lean. Most Hondas run a speed density system from the factory. When you do a few bolt-on mods to one of them, they usually run very lean under full throttle. And you can't go in with an SAFC and add fuel by going positive because the ECU will then think it is somehow seeing boost and throw the car into limp mode. The OEMs also like to put the air temp sensors in stupid spots that cause them to constantly be heatsoaked and reading way too high.
The best part about speed density on a DSM is that when you blow off an intercooler pipe, you can still drive the car like normal.
Linear Mode
