Did some searching and people say the S5 NA and T2 AFM's are different. I looked at the FSM and they show the exact same resistances for each. Can anyone explain this or elaborate. Thanks

Chris

 

they are different.

 

Good explanation and elaboration.

 

Lol, so true.
The difference is that the NA is a 1 BAR and the turbo is a 2 BAR. This allows the turbo afm to compensate for the higher volume of air ingested by a turbo engine.

 

But the resistances are exactly the same between the 2. Would this not mean that they produce the exact same voltages at the exact same temps?

Chris

 

No idea, I've never dealt with a turbo afm. But I have read post by several knowledgable people that the TII is calibrated for higher air flow.

 

Taken directly from the rotaryresurrection site, on the turbo swap page (this is of parts needed for the swap):

"Turbo air flow meter (your old nonturbo afm will get you by if you cannot find one, however the turbo afm is calibrated for slightly higher air flow on top end so it is something that might matter once you begin to push the car)."

 

now is there any gain for someone with an S4 to use a S5 afm?

 

The AFM doesn't know what the pressure is. From what I've read the TII unit has a stiffer spring so that it doesn't bottom out with the increased airflow required by the turbo. The resistance and the signals might very well be the same, but the signal for a given amount of airflow will be different in that case.

 

They are two different part numbers.
Shouldn't that be end of discussion?


-Ted

 

The discussion wasn't "Oh man I think that you can use them on either because of what I read in the FSM". It was "Can someone explain why they would show the same testing procedure because I was interested in knowing". I'm not an electronics genius. Of course they're a different part number, but no that wasn't the end of the discussion.

Chris

 

They have different spring resistances. The Turbo's is stiffer so it can flow more air before reaching reaching the fully open position. Putting a Turbo AFM on an NA would make it run leaner, and putting an NA AFM on Turbo would make it run richer up to when the AFM maxed out early, then it would start to lean out.

This could not be more wrong, since AFM's measure airflow, not pressure. You're obviously thinking of the MAP sensor.

No, it's been proven to make no difference.

 

I was running an Apexi S-AFC on my S5 turbo which shows the air flow as a %.
At 12PSI & WOT even the S5 turbo AFM would hit 100% before 5K.
Above that the ECU is basically speed/density mapping the injectors.
I switched to a Cosmo AFM and it hit 100% at around 6K.

 

Thank you very much. That explains a lot.


Chris

 

Sorry about that. I guess I was thinking about something I read with regards to upgrading to a map sensor. It makes sense now that I think about it.