which mpfi system is better, hotwire, or the flapper air flow sensor? im going to turbo a na mpfi motor, and need to know what computer system would be the best. and what years they came on.

All the SPFI's I have seen, are hot-wire. My 87 Turbo is VAF (Vane Air Flow, i.e., flapper), my 86 XT Non-turbo was also VAF. I dunno if the later ones were Hot-Wire or not...

There were hotwire turbos the first year was probably 88, these also used the crankangle distributor. You might run into trouble is you take parts form a fulltime 4wd turbo with an automatic. I'm not sure if the TCU for the 4EAT ties into the ECU, like they do with legacys.

Thats interesting.. I have had some questions about hotwire versus vane.. my 87 is a hotwire, but I see one post above that says their 87 is a vane type, and skips 87 is also vane type.. but my 87 is hotwire.. weird

I was under the impression that '85/'86 was the early style and '87/later the newer style? '86/'87 could depend on early/late?

well, i just pulled an ea82 mpfi out of the junkyard today. its an 85 xt. i got the wiring, the computer, the long block, and the maf sensor. looked like a flapper to me. would this be a good one to turbo? are the older ones the same, turbo, or na? like is this computer just waiting to see boost?

The hot wire MAF came out in 87.

 

Caleb mine is a hot wire.

 

The 85 was a vane style ie flapper door MAF

 

Arguments Pro Con

Hot wire

Pro -

less restriction to the flow of air

more accurate in all temps

With it you get a crank angle dist. as Craig says, which is more accurate for firing fuel and controls ig. timing.

Quicker responce to air flow changes

 

Con-

not "tuneable"

with it you get the ECU controled over boost fuel cut

bit more fragile than vane

 

Vane style

Pro -

Has a tuneable spring loaded vane, less spring tension = richer mix

Has a over boost switch which can be easily unplugged

 

Con -

Moving mechanical parts

Some restriction to the air flow (has to push the flapper open)

Standard distrib. with vacuum advance diaph.on side.

 

Hope this helps, if I missed anything or errored, please chime in

does that go for na and turbo? thanks skip!

yes the basics are the same but the ECU's may be different.

Sorry I have no info on the NA systems.

im sure it will work ok... we'll see:banana:

so is there a cfm that will max out the movement of the flapper?do i have to put a checkball on the vaccum advance hose, so i dont boost the disty?

Went out and looked at my car, cuz my curiosity was up. I do not have a vac. advance on my dizzy, and my MAF LOOKS like a Hot-Wire type, but it has a plug in the side, adn if you take the plug out, there is a screw behind it that looks like an adjustment screw of some kind. Do I have some weird system??