87 hatch

I have an 87 gt and the air filter intake is called speed density. What does this mean and how does it compare to Mass Air Flow Sensor?

Djs94stang

Speed density FI meters the fuel according to engine speed. This system is useless if you make modifications since the FI system is basically set for the stock setup. Mass air flow systems actually measure the mass of air that the engine takes in and meters the correct amount of fuel for any given amount of air. With the MAF system you can make mods that will increase the volumetric efficiency of the engine and the MAF will cover it.

87 hatch

so your saying that if i made modifications that required more fuel, then i would need to get bigger injectors since my computer cant adjust it?

fats429

NO it means you hafto convert to mas air system

the coumpter is set to stock engin combo and can not make adjustements for mods IE the coumpter is dumb and blind
the mas air systems measure the air intake and give the fuel to suite . as soon as you want to do mods you hafto convert to mass air or get the speed dens coumpter reprogramed FOR EVRY ENGIN MOD so they hafto all be done at once and a new coumpter made or make a new coumpter after evry engin mod UNDERSTAND

CONVERT TO MAF FI SYSTEM

87 hatch

how the hell would i even start to convert to mass air? is it easy to do ? and would that change anything with my smog?

bmorrisj

you need a mass air eec (a9l, a9p,a9s... etc) , mass air tube and sensor with the electronics and a good length of the wires so you can move the correct wires around on the eec harness.... and a 88 cali+ intake tube....

Djs94stang

I believe you can get a MAF conversion kit. I've never converted one but I can't imagine it is too difficult.

83GT306

Here's some instruction on the conversion....it says for a Lincoln Mark VII, but it also applies to a Mustang, the only thing different is the cruise control re-wiring, the computers are the same.

http://www.lincolnsonline.com/article77.html

roundman

speed density sytems don't really measure the intake air flow, they imply what the flow is by using the signals from the TPS sensor on the throttle body and the vacuum signal in the intake manifold along with several other sensor inputs to attempt to match the fuel injector pulse width to the air flow entering the engine in order to control the air/fuel ratio and make the engine run correctly. the programming in the ECU is based on the stock cam being used, so the speed density system does not respond well to changes in cams but you can do other mods that will work fine with the system. things like headers, chip, less restrictive intake and exhaust, better heads, etc. will work with speed density systems but don't change fuel injectors or the cam too much or the system wont' be able to adjust for those changes.
MAF systems actually measure the intlet air flow and temperature so they can respond much better to mods than a speed density system can. they also have a more sophisticated computer program which works with the MAF to allow better control of the engine functions. You can get a complete plug in MAF conversion kit form Ford Racing Performance Parts for around $600 which comes with a MAF, new ECU, and wiring which just plugs into the existing harnesses once you replace the ECU with the new one.
Speed density systems were the first systems used for computerized fuel injection but they have been replaced by MAF sytems since '89 in Stangs as the MAF sytems are just better for control and emissions purposes.