AFM interchangeability

[mullett]

Ok, those of use who have 80s Toyotas (Like my MR2) suffer from those terrible flap-type AFMs. I've heard that if you use an air/fuel adjuster, you can actually change AFMs. What are the limitations of this? I assume that you can't go to a skyline vane AFM or similar, but how about a 7M-GTE one for a 4A-GZE?

RM.

[ViPeR_NiPPleX]

7mgte one is a karmen-vortex variety, outputs a frequency at 5vdc instead of a varying voltage like the traditional flapper door types. 7m-ge on the other hand might be on of the bigger flapper door ones, worth a look.

[mullett]

Ok, so as long as it shares the same voltage range for output, it's adaptable? Or could you (using an interceptor) adjust the voltage of any AFM to suit?

RM.

[ViPeR_NiPPleX]

more so if its a variable resistor, then u shouldnt have much problem... however how linear the resistance is vs airflow is another story, if you are playing with AFMs, an interceptor would be a good idea....id look into the jaycar one just coz its cheap.

[mullett]

Yeah, that's the plan. So I can use pretty much any AFM with the same voltage outputs? Even a vane-type?

RM.

[ViPeR_NiPPleX]

im not sure, depends how capable the interceptor is i guess...

[whatthe?]

Well, if the 7MGTE one is anything to go by you also need to make sure that it suits your engine, as changing the stock 7MGTE AFM over to the 1UZ job which is the same voltage and type but with a bigger throat RADICALLY changes trivial stuff like AFRs

Thats the reason why they dont recommend doing this mod without changing injectors as the AFM is telling the ECU it's getting less air than it actually is, hence raising boost cut which is one of the advantages of doing it

And yes, with an air/fuel adjuster it can be tweaked, I use an SAFC2

[mullett]

So using a 1UZ one or similar would work just fine, as long as I used an interceptor? Or wouldn't that be enough?

RM.

[whatthe?]

I'm not familiar with the interceptor, but as long as it allows you to change fuel/air mix at a given RPM I cant see why not

Edit: My original post might not have been clear on my point; what I was trying to say is that there may only be a certain amount of adjustability in an AF converter of any type, so you might want to watch AFM sizing depending on what sort of motor you have

[mullett]

Ah, I'm with you now. Interesting...auto electronics is somewhat of a black art to me, but it seems that most of these sensors simply emit a varying voltage based on their signal. Hmmm...

RM.

[wiso]

dude little tip

an st162 afm works directly on a 4agze, they have the same outputs voltages, pins are the same, they work perfectly, thats what my old 4agze one was running, cause i wondered why the afm was soo much larger than the normal 4a one (well not that much, just a little taller), they have a 3" outlet instead of the 2.5". It ran pretty well, wasn't any hungrier than a normal 4agze on fuel

you just may have to adjust the screw for idle air bypass

[Lonewolf]

Air flow meters have a few ways of running. the flap door ones normally change in voltage, which... funnily enough makes for a cheap dyno if you have a multimeter that stores max/min values. the hotwire ones work of a varying current, as more air passes the hotwire cools off, so in turn demands more current to keep its temp static.

They are the ones i'm familiar with, havent played with MAP sensors.
But as viper said earlier there are ones that send out a frequency based signal, and without some middleman device to convert one signal to another, they wont be interchangable.

[mullett]

No worries. So the flap ones are mostly interchangable etc. Any idea what the actual thru-flow diam of the ST162 AFM is?

RM.

[wiso]

no idea man all i can tell you is they work fine

[sw20r]

I was thinking about this the other day.. What boost do the other toyota afms max out at? Apparently the one on the 3SGTE is no good after 1BAR as its a restriction. Instead of going a map route I might use a piggy back and tune the AFM instead of going MAP which needs to be absolute