elton

wassup,
i know there's been a lot of talk about the air flow meter being the most restrictive part of the intake which got me wondering. . .

here in Canada Mazda produced a the MX3 a.k.a. the Mazda Precidia. this car might also have been sold in the states but not sure. Anyways from '92-up these cars come with a nice big round style air flow meter which definitely seems to be a lot less restrictive than the stock flapper. I was just wondering if any one knows how hand it would be to swap one of these into an RX7 if it's even possible????

Just something to think about!!

Rxmfn7

iTrader: (4)

Not too sure about Mx-3s, but it is probably the same one used on a 2nd gen ProbeGT, or Mx-6. This cone style is the exact same one used on 89-91 Rx-7s. Also 1st gen mx-6 GTs and PGTs ( I think) have the same AFM as 86-88 FCs.

jon88se

ok, the cone AFM looks to be more restrictive than the flapper bc the cone is actually IN the intake path and doesn't open, it just moves in and out. the flapper AFM looks like the superior one for flow, the question is how is the cone AFM programmed...does it run the car leaner than the flapper?

elton

is it easy or even possible to swap the cone style AFM out of a 89-91 Rx-7 into my '86??? I know the ecu is probably different. . .

Icemark

The flapper type was used for quite a few years on the Miata, and a common upgrade is to use the FC S4 flapper on the Miata.

The Miata and the base/mid range MX3 used the same 4 cyl, but the Miata always had more HP.

It would seem to be going the opposite direction to use the cone type.

And the flapper type found on the FC was typically not a restriction to the air flow until you got around 350HP.

Remember the big reason for Mazda to switch from a Flapper type (S4 cars) to the cone type found on the S5 cars was that the cone was cheaper to build and more forgiving on installation. It was not a source of additional HP.

Pinfield357

there was a thread awhile back that was saying the exact opposite of whats being said here. they said that the cone style was less restrictive. and i hope that it is cause i wana install that on my 87 T2 so i can just put on a cone filter with out an adapter

Rxmfn7

iTrader: (4)

I dont think all the hassle associated with changing over to a cone-style AFM is worth it just not to have to use an adapter...

mazemaster

Try this:

elton

Thanx guys!!!

Spawn VII

ok... i'm a little lost with the diagram... what does the colored lines mean? and is that the harness side or the afm adapter side shown??

mazemaster

For this mod, besides aquiring the S5 afm, you also have to have the connector for it since the S4 connector is not used.

The diagram displays how the wiring relates from the S5 connector to the S4 connector and as such is connected to your existing harness.

If you are still having problems reading the diagram, I would highly suggest getting someone who understands it to help you out when doing this mod.

PS: Also when converting to the S5 afm, the fuel pump cutoff protection is eliminated.

KiyoKix

I've been thinking about doing this swap, I didn't realize it was that damn easy! Any pics of you it looks inside the car (fitting)???

Spawn VII

i guess what i meant was... am i looking at the afm side plug?

Ronac

Is there a way to mod the s5 afm?
Like drill holes in it or maybe enlarge the diameter or the entire thing?
I'm probably doing to get flamed for this, but oh well..

Aaron Cake

iTrader: (1)

And you'll need an S-AFC to tune your fuel curve afterwards...

Really, AFM "upgrades" are not worth it on stock or nearly stock cars. And by the time you get to the point where the AFM becomes a restriction, you should have a stan alone system anyway...There are PLENTY of 400HP+ FCs in Japan running the stock AFM...

88IntegraLS

How much more airflow is the S4 turbo AFM cabable of metering vs. the NA meter?

rx7_turbo2

I've never been a believer in removing the AFM, or modifying it. I don't think it will make enough horsepower to be worth it at all. I will increase throttle response.

It's been said a million times. If you want to get rid of the AFM go standalone.

Ronac

Not get rid of the afm but maybe modify it so it can be less restrictive. Or is there a way you can take an afm from some newer cars and correct the electrical signal with resistors?

j9fd3s

iTrader: (3)

none, the hole is the same size. after looking at the s5 and s4 meters id say the s5 style is less of a restriction when its not all the way open, but once they are both open the s4 looks better, as its just a square hole

mike

NZConvertible

It's not. Any benefit that might be there because of the shape (and I don't believe there is) is negated by the fact that it has a smaller opening than the S4 AFM.

If you 're going to go to the hassle of swapping in a different AFM, it needs to be something significantly better than stock to provide a worthwhile or even noticable difference.

Ronac

What if we can find a sensor that isn't a flap type or cone type. I think newer sensors are way less restrictive than the ones we have on our rx-7. The s5 one has an inlet of 2.5" and the rest of the tubing is 3". It just doesn't make sense to me.

Ronac

something like this
http://www.jdsperformance.com/index....tem&inmake=all

The advantage is probably not worth the price but I'm pretty sure some newer cars have this kind of sensor built in them. So maybe we can just get one from the junker for a good price and we might have a decent mod.

NZConvertible

You cannot use a hotwire MAF sensor on cars that came with a vane or cone AFM. The output is completely different and requires complex electronics to make it work.

Any drop-in swap must be a bigger version of what we already have.

The only AFM I know of that might be swappable (with a fuel computer to tune it) is the cone-style AFM fitted to the JC Comso (13B and 20B). I've never seen it done though.

Evil Aviator

The AFM doesn't create as much restriction as you think. The main performance advantages of going to a standalone are:
1) AFR may be tuned for better performance and fuel economy.
2) The faster standalone ECU is far superior to the slow stock ECU (especially vs the incredibly slow S4 ECU).
3) Ignition timing may be optimized for performance.

Getting rid of the AFM restriction does help some, but it's a very minor amount, and is certainly not worth worrying about or spending lots of time and money "fixing". When you hear the standalone EMS proponents (myself included) talking about getting rid of the restrictive AFM, you need to understand that this is just an added plus, and not the main purpose of a standalone EMS. Getting rid of the stock ECU is the main purpose of the standalone EMS. Those of you who build your whole life around getting rid of the AFM but still running the stock ECU are really missing the boat on this one.

I would also like to point out that a standalone EMS does not necessarily mean a speed-density (MAP and rpm sensing) system. Depending on the brand and model of EMS, it may also work in Alpha-N mode (TPS and rpm sensing), or even work in mass airflow mode with the stock AFM, aftermarket AFM, or aftermarket MAF. Yes, that's right, some standalones use AFM's. This is because the mass airflow system will stay in tune with minor changes in the engine due to wear, break-in, deposits, etc., which is why auto manufacturers choose this method of management for their street cars.

j9fd3s

iTrader: (3)

good stuff.

alpha n is hard to get driving, we have tried both ways on the same car and the map style runs smoother

mike