I bought an SLP MAF and saw something interesting
(to me, anyway, and maybe to anyone else who makes
physical modifications to their MAF like porting
or MAF ends).

SLP (I presume) has soldered on an extra metal
film resistor across one of the sense wire
resistors in the bridge. See pic:

http://community.webshots.com/photo/...62585024hfdzqE

This would produce an offset and/or a scaling
depending on the electronic configuration.
The resistor is going to have a different
airflow - resistance profile (and most film
resistors are meant to have a negligible
tempco, unlike the hot wire sense resistors).

This points to the possibility that people
could do "MAFT" type tunings for about $0.19,
if they only knew the right value of resistor
for the desired result.

SLP was clever enough to mount it with the
markings out of view, and I'm sure the proper
value comes down to cases anyway. But, on my
unit the value is 2.64Kohms (I gently desoldered
it and measured). Using a good quality 5Kohm,
20-turn trimpot external to the air path, but
connected the same, you could have some DIY
adjustment range. Refinements might include
combinations of serial and/or parallel
resistors to make for a low-drift fixed plus
finer adjustable term.

Food for thought, have at it....

 

Apparently, what you found is how SLP calibrates the MAF sensor to match up with stock LS1 MAF tables. Very interesting, but this would be expected, that is, a shift in the outputed frequency.

BTW: The MAFT has a "two stage" effect, one for part throotle (which I assume is from 0Hz up to about 8,000Hz?) and one for WOT tuning.

 

I presume that the desired effect is a scaling,
rather than a baseline shift. I don't have any
info on which resistors do what in the MAF.
I vaguely grasp the concept, which is that
the electronics attempt to maintain the MAF
wires at a certain resistance setpoint by
throwing current; given that the output is
a frequency, I presume this is a fixed pulse
width, pulse-rate-modulated power delivery
(although it could just as easily be a linear
driver and a VCO off the same master voltage,
I think power efficiency indicates a PWM/PRM
for most modern automotive electronics power
drive).

So a shunt resistor across the prime sense
element would raise the required current and
the indicated frequency / airflow. This makes
rich and high demand tendencies (good). Never
heard of anyone wanting to go leaner after adding
MAF ends....

If the obvious physical similarity to the OEM
unit in the arrangement of resistors is any
indication that they're the same in the guts
(more or less), the trimpot might be something
to try. Tuning with a screwdriver is just more
soul satisfying than tuning with software. <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

 

yes, thats all it is.

now somebody tell me the resistor value needed to make a stock meter read 11250kz at 1024 g/sec and i will be a very happy fellow.

 

It's the kind of thing you'd just need
a good flow bench, a 5V supply, a 'scope or
frequency counter, a DVM and a variable
resistor to try.

I'm short one flow bench....

Whether or not the output's nice
and linear after you cobble on a
resistor is another matter too. Again,
flow bench & record data.

Who's got a 1000CFM flow bench (with
decent flow reporting accuracy)?