MAF use and calibration

["NickG" <nikog@mediaone.net>]

> Ok  FROM WHAT I'VE FOUND  mass air is a direct measurement
> of the amount of air going into the engine.

Right.

> The maf vr rpm is just a calibration of the maf..

Actually, the MAF Transfer Function is the calibration of the maf. The
voltage output of the MAF represents a certain amount of oxygen passed
through the meter. The transfer function tells the ECM how much O2 each
voltage level equates to.

>So for a maf application.. the tables theoretically should not change for
>any motor you put the maf sensor on.. as long as that engine is within the
>span of the maf..

Correct.

>once the signal from the maf is calibrated to a flowrate... it should not
>change on any motor....

Rather, once the transfer function of the MAF meter is determined, it
doesn't change regardless of what engine it's used on. It DOES change though
if you change the way air flows into or out of the meter.

>As disscused before on this list.. the maf runs into trouble with high perf
>engines because the engine pull more air than the ul of the maf.... Or the
>range of the maf is to narrow....if their was a maf that would measure a
>higher amount of flow it would be ideal..

Easily found......use a Ford (gasp!) MAF meter. You can get these
recalibrated with virtually any flow measurement range you want. For
example, a 36lb/hr curve can measure 514gms/sec when outputing 5.00v.

> cept you would then have to edit the tables to reflect the output of the
> maf to actual flow rate...  another option that was discussed was to
> somehow patch the code so the maf range was 16bit instead of 8..
> hence doubling the range.....

The '165 ECM is setup to use an 8-bit value for the MAF reading, whose max
is 255gms/sec. To double this, you only need to add 1 bit, for 9 in total,
not 16. Going to 16bits would increase the range by 256 (not 2).

> I'm working on that right now by adding a table like the ve on the 730

Please let us know how it turns out. Inquiring minds want to know :)

Nick

ps. could you look into turning off the MIME encoding when posting to the
list? Thanks :)


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