Many cars for fuel efficiency or performance. In modern fuel injected cars, secondary intake and fuel injection systems get more complex with rpm; typically it

Many cars for fuel efficiency or performance. In modern fuel injected cars, secondary intake and fuel injection systems get more complex with rpm; typically its about 3500 rpm or 50% throttle position cause a different fuel map, an intake runner flapper, and for the last 30 years, some automatic cam timing adjustment.