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The SN95 stock Mass Air Meter has a post that restricts airflow inside
it, by removing the post your stang can get some free HP.
Actual Dyno test have not been recorded for this modification, but all
users agree that there is a clear increase in performance.
This modification has been performed on 5.0 and 4.6 SOHC liter SN95s.
UPDATE: Please read the Following
notes to better understand the implications of this mod.
How to guide
You will need a few tools to get the job done:
The first step is to remove the air box assembly, start
by removing the air filter and air silencer (if you still have it in
place, its a good time to get some extra HP by discarding it), and disconnect
the MAF electronics from the wiring harness.
Disassemble the air box and get the MAM out. Remove the
meter tube back plate and discard it, you will not use it again.
Remove the Torx BIT screws (T20 size Torx bit) that secure
the Metering electronics to the MAM housing (shown in black in the picture).
Be careful not to touch or break the wires.
To cut, loop a hack saw through the Mass Air Meter housing
, be careful not to scratch the housing, leave as little material as
possible. The MAM has a round sample tube, be careful not to cut it.
Use the Dremel tool with a medium grinder to remove the
excess material. Remove all material around the sample tube, leave it
as round as possible to avoid turbulence.
Now that you have all the excess material off, start to
sand the MAM circumference, use the 200 grit sandpaper to remove the
unevenness of the surface, use the 400-600 grit to give the surface
a polished feel.
Don't discard the round metal screen mesh that is used
in the Mass Air meter, it provides with added protection against particles
and also straightens the air flow.
IMPORTANT:
Info provided by BillW
on August 13, 2001 at 09:06:09:
WOT fuel is calibrated to a point 6-10% RICH of LBT (lean
best torque) in an effort to inhibit detonation and protect catalysts
to be destroyed by overheating. That means there is some power to be
had by LEANING out the A/F from the originally calibrated point. By
removing the post you HAVE reduced pressure drop across the air meter
and lean shifted the WOT fuel.
Removing the crossbar and enlarging the cross-section
of the meter (porting it) can affect the WOT (open loop) in 2 ways:
first by permitting MORE air to pass per given voltage than the EEC
realizes, you have shifted the transfer function lean. And at WOT, there
is NO feedback Air/Fuel, so desired A/F is assumed to be correct, and
is not actually measured. (We will cover closed-loop A/F in my next
point.) and second, you can very likely (in a high horsepower application)
reach the Vmaf clip (~4.9V) SOONER so injector pulse width is not updated
with airflow info and the system leans out.
Now, for closed loop, it is very possible that the error
in the Voltage MAF signal can be "corrected" within the confines
of the adaptive fuel strategy. The EEC will do its best to stay at 14.7:1
A/F and has the ability to iterate about that point by correcting the
commanded fuel pulse-width a certain percentage. So it wont be a surprise
if you don't experience idle problems, fairly low airflow at idle, times
an error signal means not much error at idle.
Now, if you are using an open filter element, HOT under
hood air is perceived by the ACT sensor and the spark signal is modified
to prevent tip-in detonation and steady-state detonation. There will
be GREATER effect of fan wash and other turbulent air sources on the
transfer function than the hot air does at speed since the system cools
down to some point not too far above ambient. Not exactly ambient, but
not the 180F you can see sitting still.
Not all cars are created equal, some variations can occur,
one of those is the fact that not all 94-94 (5.0) have the same PCM
(EEC) versions.
Each version would have some different variables programmed into it,
and those would be the result of software bugs found by FORD or improvements
to the stored look up tables or part of the programming.
Some SN95s (5.0) are notorious for engine detonation ,
which in some cases has to be solved by changing the PCM or by adding
a custom chip. In such cases of a SN95 presenting some degree of detonation
this modification is not advisable.
It would be a wise idea to try this modification with
a junk yard MAF, go buy one and test it.
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