afm signal vs map signal?

[Shifty]

as a general rule map sensors put out 0-5v, what kind of signal does an afm send?

[JustCallMeOrlando]

The 1G AFM from memory is somewhat similar, 5V closed and 0V open. I vaguely think they're that way around, but it has been ages.

[RA35GT]

Some of them are the same, some have a variable frequency output.

(they are not equivalent in terms of load sensing)

[oldcorollas]

which AFM? flap type? hot wire type? cold wire type? vortex type?

[MWP]

In case you are wondering.... no you cannot use an AFM instead of a MAP sensor, or vis-versa without changing the ECU.

IIRC Karman-Vortex are variable-freq, the rest are linear.

[Duk]

IIRC Karman-Vortex are variable-freq, the rest are linear.

Linear what?
Nissan hot wire AFM's aren't linear in their air flow to voltage output.

[thechuckster]

neither is a gen 1/2 3SGTE AFM - resistance is not linear across opening of flap - mapped out it looks more like a saw-tooth.

[MWP]

Linear what?
Nissan hot wire AFM's aren't linear in their air flow to voltage output.

Yeah, didnt mean linear (probably almost none are), i meant have voltage outputs.

[gixer]

IIRC Karman-Vortex are variable-freq, the rest are linear.

Holden are frequency

[Norbie]

In case you are wondering.... no you cannot use an AFM instead of a MAP sensor, or vis-versa without changing the ECU.

There used to be converter boxes available for this sort of thing (I remember they were popular on 7M's a while back) but I don't know if they're any good. A new ECU seems like a far more sensible option.

[andrew_mx83]

There used to be converter boxes available for this sort of thing (I remember they were popular on 7M's a while back) but I don't know if they're any good. A new ECU seems like a far more sensible option.

really?

i tried to get rid of my AFM for years, i fcken hate em but didnt want to go to an aftermarket ecu

i ended up going to straight lpg to get rid of it, worked a treat
and the new build is going to be carburetted so even less of a worry

[thechuckster]

...so instead of a midget hiding in the engine bay pouring petrol down a noisy hole (aka a carbi), you have a similar-sized man hiding in the engine bay with a bbq gas tank spraying vapour down the same hole

[andrew_mx83]

na no midgets lol, got a BFO holley 650DP (34mm primaries and 50mm secondaries) for now and a set of triple 40mm dellorto's for after its run-in the "midget" will be dumping fuel in with a bucket LOL

the gas was actually awesome on it, had a big 425 mixer and AFM delete, lost no power going from petrol to bbq gas. and the consumption dropped from 18-20lt/100 petrol to around 14 on gas

[amichie]

I have played with a few different sensors and hooked them up in series with a garden blower set on vacuum. I will dig up the results and post them up.

I had a 7MGE VAF in series with a nissan hotwire MAF of an r33 turbo and a GM hotwire MAF. The only one that had a frequency output was the GM.

[auto351]

I have played with a few different sensors and hooked them up in series with a garden blower set on vacuum. I will dig up the results and post them up.

Would be interested in see these results

EDIT:

The 1G AFM has two parts
a) Digital portion which indicate if the plate/flap is fully closed (used to interlock fuel pump & not wired back to ECU) in this case the circuit is open, otherwise the circuit is closed
B) is the linear operation which indicated the actual plate/flap position and it ranges form 0-6V (when connected to the ECU) there are also some other resistor in the AFM for temp compensation.