Grifnsqest

I made a visit to Jeff a couple of weeks ago. He didn't like the amount of air being measured. So, we took a silicone coupler, that fit perfectly inside the MAF, and stuck it in there.

I questioned it, because I didn't understand the reasoning behind upgrading to a larger diameter MAF, if you are just goin to reduce it with that coupler. His explanation, from the way I remember it, was that it helped focus the air around the sensor itself. It could get a better reading.

Don't know if that helps, but... my two cents

nyet

velocity * area == mass air flow.

MAF measures velocity. Reduce the area, and the same air flow will read higher.

ModifiedA4

the MK1 TT 'guys' have been upping there maf diameter and fuel pressure as part of a mod for some time now.

effectively maf scaling in practice. i think they call it the "BAMM" mod.

VonK :: Retired

Actually,

velocity*area=Volume flow rate.

But your argument is still true.

homer-j-fong

hehe, and we don't "measure" mass flow rate, we "measure" estimated volume flow rate and "CALCULATE" mass flow rate.

You would <b>totally</b> have to stop air flow to "measure" mass flow rate

soooo, tell me how the B5S4 ECU calculates load. That is the million dollar question =)

nyet

the MOMENT i hit post i knew somebody would call me on that..

figures it would be you

VonK :: Retired

1. The whole trick about the MAF sensor is that it <b><I>does</i></B> measure <b><I>mass flow rate</i></B> regardless of air temp and density. So the ECU gets the mass flow rate directly from the sensor and doesn't have to calculate it.
2. You say <font color="blue">You would <b><I>totally</i></B> have to stop air flow to "measure" mass flow rate </font>
Please explain.

homer-j-fong

Calculations have to be happening somewhere.

Correct me if I am wrong here but for the sake of our argument can we agree on "this" particular topic that;

mass flow = the weight of air passing per unit of time


how could any MAF sensor possibly know the total actual weight of "flowing" air without bringing it to a complete stop? It could be accurately estimated for sure, but the "actual" weight could only been known by confining a known volume of air and weighing it, no??


Thanks for the conversation Vonk, you always get me using (or trying to) the old noodle. When my head is clearer maybe I can come up with a better argument, hehe.

On a side topic, do you know how our MAF actually works? My mind is still stuck back in the days of vane type air meters. Maybe that is why I am arguing a pointless topic : )

Cheers

VonK :: Retired

---&gt; element to the air stream. The temperature change of the air, as it streams over the heated film, depends on the number of air molecules coming in contact with the film, and this is proportional to the air <B><I>mass</I></B> flow. The ECU calculates the MAF rate from appropriate voltages received from several temp measurements in the sensor.

Enjoy the long story. <ul><li><a href="http://s4wiki.com/wiki/MAF#Logging.2Ftuning.2Ftrouble_shooting">The long story</a></li></ul>

homer-j-fong

my point was that it is still a calculated value. Meaning even if you know the mass around the probe you are still calculating the total mass of air passing thru the housing. The only true way to get a %100 accurate measure of mass would be to totally stop a set volume of air and weigh it. Everything else is just a good estimate.

Sorry, I am a stubborn ***** when I have been drinking =)

Thanks for the good back and forth Vonk. It's all just nit picking. Have a good night sir.