JaxJags88GT

Ok fill me in on this, i have a 88 GT, i've converted it to mass air, i knew it needed to be done to add mods and have the computer adjust for it, but fill me in on this: what is the difference in mass air and speed density and how does the speed density actually work?

Tims 88GT

search throe the form there are a few post that go into detail about it.

stanglx2002

just read back a page or 2 and you will find what you want

87mustang347

the computer on speed density is already calculated and programmed to no how much air is comming in threw the tb. lets say it prgrammed to the tune of 50cfm. the reason y speed density is so bad for modded cars is cause once u start to add on heads tb's and cams, the cfm is no longer goin to be comming threw the tb at 50cfm, itll be 300cfm or something like that. so now that u got 300cfm goin threw your motor and the bigger injectors if u have them, the ecu is still only readin 50cfm becasue that what its programmed to read. i had a speed denstiy car too but i converted to mass air. i had a tb, cai, pullies, and exhaust and the car ran fine. nce u start to get into more heavierstuff then ull run into problems.

roundman

speed density systems imply what the air flow into the engine is by a combination of readings from the TPS sensor, the MAP sensor, the engine rpm and the engine temperature and the programming internal to it telling it the cam specs etc. since it doesn't actually measure the air flow like the mass air sytems, it cannot properly respond to changes in the cam specs that happend when you change the cam. the spark timing and fuel injectors pulse widths built into the ECU are all based on the stock cam and the maps for them in the computer can't be changed easily if at all, so that's why you needed to upgrade to the mass air control.