NZConvertible

You're right, it does, but in my educated opinion (not hearsay) the difference in internal shape wouldn't be enough to overcome the fact that the S5 AFM's inlet is considerably smaller, not to mention even when the measuring cone is fully retracted the gap between the cone and the outer wall is pretty small. Any difference in flow is likely to be minor but I'd be very surprised if the S5 AFM came out better.

Since that sounds like you're talking about AFM's in general, not just the stock one, you'd better go tell that to all the car manufacturers who still use them. If you mean the stock ECU is archaic and should be replaced with a decent system then you'd be right, but an AFM is still a far more accurate way to run an engine than MAP sensing. Unless you're looking for extreme power then an aftermarket programmable ECU using a large AFM (or two) would be a much more flexible set-up. People say the big advantage of a programmable ECU is being able to easily retune for extra mods, but the big advantage of an AFM would be not necessarily having to retune for those extra mods.

See above. I don't understand why people think the airflow would be so much smoother.

It evolved from expensive aluminium to cheap plastic. Bit like the swap bar links...

It will work fine. The connections shown are correct.

slpin

iTrader: (9)

NZ

you are not thinking clearly
just because it is 10% bigger, doesnt mean it will flow 10% bigger.
it MIGHT flow 10% more if they are both maxed out.

on his NA, will it ever suck hard enough for the s4 afm to max out?

and since it wont max out, you will still benefit from the smoother airflow on the s5 afm, right?

thats why people do TB mod, correct?

NZConvertible

I'm thinking perfectly clearly but you seem to be imagining things. I never said it would flow 10% more; in fact I never quantified any flow differences at all.

People who've done this say there's no gain (even you), and that's been dyno-proven a couple of times, so whatever diffences there are are irrelevant. Accept it and move on.

slpin

iTrader: (9)

i agree there is not really a gain other than mounting position
but people like you need to realize there isnt a lost either

RETed

Break out a college level fluid dynamics book and grab the formulas - you should be able to get a pretty good estimate on what POTENTIAL flow is.
We can easily measure cross-sectional area and angle of attack and all that good stuff.

All of this bickering is useless...

The unit is still measuring airflow into the engine.
The stock ECU is calibrated and mapped to handle "X" airflow at "Y" RPM and spit out proper fuel (pulsewidth to the injectors) and ignition (timing) control.

So what does this mean?
90% of the time, it doesn't mean jack **** if the AFM can flow more.
Measured airflow is measured airflow.
It's sorta like arguing if-I-get-bigger-injectors-do-I-make-more-power bullshit - we all know just shoving more fuel into the engine does not make more power.

Realistically, I think the stock ignition breaks up like crazy at high RPM's and makes all of this useless.

If you wanna swap AFM's - go right ahead.
You wanna argue which is better - go right ahead.
I bet you I can stuff a Haltech on the same car, get rid of any of those pesky AFM's, and beat whatever hack job you're doing with any of those AFM's.


-Ted

geargrabber

yup, sad to see it go... i finally got a fix-it ticket for my exhaust

coldfire

iTrader: (1)

none of this matters at all on a near stock car, IMO.
it is very hard for me to reach 50% AFM opening on a stockport NA (reading the voltage value on SAFCII).
my guess is that there may be a SLIGHT difference between the two as you reach enough CFM to approach 100% opening. BUT at that point if you are making that much power, you should be using a standalone anyways, and most people just go with a MAP when that happens...

slpin

iTrader: (9)

bravo!

RETed

Actually, the S-AFC is expecting a full 0-5V signal, and I've never heard of anyone going over 70%?
Try it - with the S-AFC on, push the AFM flapper or cone all the way in / max.
It typically reads about 6x% maxed out.
So you're like 70% of full travel?


-Ted

NZConvertible

People take the S-AFC's stupid "airflow" reading way too seriously, which just shows a lack of understanding of how 0-5V sensors work. Most readings will only ever be in the 1-4V range.

coldfire

iTrader: (1)

ok, so the AFM voltage range for the stock FC AFM has been measured to be 0-4V? or it says that in the FSM?
i didn't realize that the AFM value on the SAFC was uncalibrated...

in any case, my point is on a stock car you will not be reaching full opening of the AFM. if you are, you have other problems than having to choose between using the S4 or S5 AFM.

NZConvertible

Here's some readings i just took from my S4 AFM (igntion on, engine off, battery at 12.2V).

Reference voltage (Vref): 4.99V
Signal voltage (Vs), AFM flap fully closed: 4.05V
Signal voltage (Vs), AFM flap fully open: 0.43V

By pushing really gently on the closed flap you can get the fuel pump circuit opening relay to click on before the voltage reading changes.

I have no idea how the S-AFC works out the "airflow useage ratio" and the manual certainly doesn't offer any useful info. About the only use I can see for it is to use it for before-and-after comparisons when doing mods, like a very basic dyno. Because power is roughly proportional to airflow, if your peak airflow reading changes after performing a mod then it's had some effect on power (hopefully a positive one). The change in reading will tell you approximately how much power has changed. If your peak reading changes from say 60% to 63% then power has increased ~5% (63/60=1.05).

So I take back what I said before. It's not stupid, just misunderstood.

RETed

It's not uncalibrated.
The stock ECU has no trouble using it's range.
Reread what I said...the S-AFC expects a full 0-5VDC signal and scales it's percentage against that.


-Ted

NZConvertible

Ted, I don't think it does. If it was simply a showing Vs as a percentage of Vref (where 5V = 0% and 0V = 100%), then using my AFM readings the S-AFC would show 19% with the AFM closed and 91% with it fully open. Doesn't idling normally show low single figures?

Maybe (and I'm just guessing) it uses the Vs value during initial set-up (ignition on, engine not running) as the baseline for 0%. It's also possible that there are preprogrammed Vs values that correspond to a fully open and fully closed AFM, which are selected when you input the AFM type (e.g. 'FL-5' for S4 and 'FL-6' for S5).

Someone with an S-AFC needs to tell us what AFL readings they see with the AFM fully closed and fully open.

coldfire

iTrader: (1)

unfortunately my car is in storage at the moment...i won't be able to test this out anytime soon.

all i know is that the SAFC reads 0% when the engine is off (and like 1% at idle). i have not tried actually pushing in the cone manually all the way in and seeing what reading it gives.

HAILERS

Key ON, engine OFF: Point four closed and 83.6 full open. Finger pushing the flap all the way aft.

Key ON, engine running: .9 percent at idle (1.1 on another car), and unknown at full throttle going up a steep hill.

I think I've seen higher than 83.6 on another afm in the past. I only looked at one car. It's 19 F and I ain't a gonna do that til the temps get to the 40 F plus range.

At idle, most of the time I see a voltgage reading of around 2.7 vdc. Either car. Fully warmed up and at a NORMAL idle speed.

Key ON, engine off, I usually see the 3.87 vdc closed and .335 vdc full open

Talking AF1 here.

HAILERS

I just looked at a old thread where I told SLPIN that I saw close to 100 percent with the flap shoved full aft. He was seeing just 54 percent. Sooooooo.......I need to look at the other car sometime soon since the one I just looked at showed just 83.6 percent.

socalrotor

iTrader: (1)

Just for the record This was sorta my idea, so direct the flames at me, I kinda talked GG into this mod, if nothing else for CAI setup. BTW wouldnt the plastic S5 hold LESS heat than a ALM S4?

HAILERS

My second car reads, at the SAFC, .4 percent fully closed and 99.8 percent fully open. The Vs is 5.04 vdc. As far as voltage, going to Sns check it shows 3.925 vdc fully closed and .300 vdc fully open (99.8 percent)

coldfire

iTrader: (1)

so what does this tell us now?
if i understand you correctly your two cars gave different readings...are we talking about the exact same AFM with the exact same "flow meter type" setting on the SAFC?

having it range from ~0% to ~100% clearly shows that the SAFC percentage reading is valid for the full range of readings, unlike what Ted mentioned (that upper limit was NOT 100%).

if the SAFC takes 0VDC as full open, then regardless of the full closed voltage the SAFC should properly scale the percentage value.

geargrabber

can we come to a conclusion yet?

HAILERS

Welllllllll, time for superstition. I've heard it told that the SAFC has a learning curve. From what I understood, the SAFC has to see the full range several times to calibrate itself. Like holding full boost for several seconds several times. Then the percentage will gradually over time read higher than the 54 percent or whatever your reading right now.

I've been fooling around with my SAFC over the last few weeks. Such as Initializing the SAFC and just looking at the normal afrs put out by the stock ECU with and without the stock 02 sensor connected. It's possible I have not been boosting a whole lot in the last few weeks on the car with the low percentage level.

So, bowing to supersititon, I'll drag race up some steep hills in the next few days with the low percentage car and see if there is a change in the AFI percentage.

Seems the same thing could be done holding the flap wide open a few times. I know not.

NZConvertible

FYI, it's AFL, not AFI, short for AirFLow.

HAILERS

If it reads less than 100.% when you hold the afm flap door fully open, It ain't never gonna read more than that.

Do us a favor whoever you are. Hold the door fully open and write down the percentage. Now, while the door is wide open, go to Sensor Check and read what AF1 voltage is.

I've one afm that reads right close to 100 percent. It's 98-99 percent. The AF1 voltage at that time on the SAFC reads .300 to .305 vdc.

On the other two slug afm sitting on the shelf, the voltage is something like .355 and they don't read 100%. They read somewhere like 68 %. Door full open.

Right now I don't know how significant this is in the wide world of RX

Now let's get down to business. The manual says AF1. My SAFC reads AF1. So it's AF1 not AFL. AFL as everybody knows, stands for American Football League.

SonicRaT

iTrader: (6)

Why would a kiwi know football though?