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Mail From: (email redacted) (Robert King)

Well, after a few weeks of scrounging, I finally got all the parts togather that I needed to replace the Speed Density computer with a Mass Air system! What follows is a short (?) overview of the conversion.

But first, I would like to extend a hearty thanks to all that helped me out in preparing for this. Without you, the project would have been MUCH more confusing, and I surely would have tripped over a few things along the way. In particluar, I extend my thanks to:

Maximum Motorsports They supplied an ECU from a 1991 49-state
Mustang with AOD, a Cobra 70mm Mass Air Meter,
a custom harness for the meter, and (somewhat
incomplete) instructions.

Chuck Fry Chuck graciously donated the necessary plumbing
for connecting the air meter to the air box,
and to the throttle body. Would you believe
Ford wants $120 for this?

Clifton Koch and Did I mention that the instructions that came
Tom Stangler from Maximum Motorsports were incomplete? Cliff
and Tom's Mass Air FAQ entry (still in the
works?) took up where the "official" instructions
left off. It contained information for moving
the two AIR solenoid pins and connecting the
line to the fuel pump relay. Thanks guys!
(But next time could you publish the pin numbers?)

Dallas Mustang Parts One of my friends at DMP donated the bracket to
mount the air meter on. Once again, Ford's
price for this part was ridiculous.

Ace Hardware Trying to get the proper bolts from Ford to
mount the air meter to the bracket, and the
bracket to the inner fender was like pulling
teeth! NO ONE seemed to stock the parts, and
they were reluctant to special-order such piddling
little stuff. (If you just *HAVE* to have the
Ford attaching hardware, the numbers are:
56950-S55 for the bolts attaching the air meter
to the bracket, and N606678-S36 for the
"self-tapping" bolts to attach the bracket to
the inner fender.) A trip to my local Ace
Hardware solved this problem nicely - 3 8mm fine
thread bolts (bring your air meter to make sure!)
and 2 sheet-metal screws worked perfectly!

Before I get into the nuts & bolts of the conversion, a word about
using the Cobra 70mm Mass Air unit with the non-Cobra computer (ECU) and
19# injectors - YES! The combination works to perfection!

Apparently Maximum Motorsport knew what they were talking about when
I asked them how the calibration worked when using different size
injectors. The Mass Air meter really has nothing to do with the size
of the injectors. All it says is how much air is entering the engine.
The ECU then determines the pulse width to send to each injector to
delever the correct amount of fuel to the intake air stream, based on
information from the MAF sensor, among others. The COMPUTER relies on
certain characteristics of the MAF meter. The characteristics of both
the stock MAF meter and the Cobra meter are THE SAME, meaning that with
equal air flow through them, their signals are the SAME. The difference
between stock and Cobra systems lies within the COMPUTER sysems of the
two different applications!

Now, when you install bigger injectors, SOMTHING has to change to
accomodate the larger delivery of fuel. You can change the entire computer
out (i.e. swap your stock unit with a Cobra unit,) or you can "fake out"
the stock unit (or the Cobra unit, if you're going over 24# injectors,)
by recalibrating the MAF sensor. This essentially makes the computer think
there's LESS air entering the engine than the actual amount (remember, a
stock computer will *always* assume that there are 19# injectors.) If you
caliibrate it right, the equation will balence and you'll end up with that
good old 14.7:1 ratio!

Now, with that off my chest, on with the installation...

First off came the removal of the plastic snorkle that ran from the
airbox to the throttle body. Removing it was simply a matter of
loosening the two screws retaining the clamps at each end of the hose
and pulling it off.

Next the racket used tO