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Yan88gt · 02-08-2002, 08:40 PM

It's not the change in vaccum that make the speed density idle bad. It's because it can't add extra fuel. If you add 30% more air on a mass-air car, it will increase the duty cycle( pulse ) of the injectors but not speed density, it have fix tables in the computer. So if you add 30% more air on SD you will need to add 30% more fuel. How? With a fuel pressure regulator or with custom chip wich increase the duty cycle of the injectors. I do not have a cam on my car but if i lower the fuel pressure it will run like crap.

02-08-2002, 08:40 PM	#12
Yan88gt Registered Member Join Date: Jun 2001 Location: Quebec canada Posts: 92	It's not the change in vaccum that make the speed density idle bad. It's because it can't add extra fuel. If you add 30% more air on a mass-air car, it will increase the duty cycle( pulse ) of the injectors but not speed density, it have fix tables in the computer. So if you add 30% more air on SD you will need to add 30% more fuel. How? With a fuel pressure regulator or with custom chip wich increase the duty cycle of the injectors. I do not have a cam on my car but if i lower the fuel pressure it will run like crap. __________________ Ported stock heads and intake, 65mm throttle body, 1.7 roller rockers, pulley, superchip,afpr, electric fan, motorsport headers, magnaflow cat-back, hurst shifter, 3.55 gear, speed density computer 12.81@ 104.7 on E.T street (1.77)