Once the "fixed components" such as the manifold,
injectors and major sensors are set into place we can bring
in the electrical. There are several companies that make EFI
harnesses but as we found when we converted our truck from
speed density to mass-air, the guys at RJM Injection Tech
(
FordFuelInjection.com
) really have their act together when it comes to harness
design. Their harnesses are not simply 5.0L Mustang production
wiring that has been hacked and whacked to fit other cars.
They are built from the ground up with features such as low
amp draw for compatibility with early vehicle ignition switches
and the correct wiring lengths to reach long tube headers.
As you'll see, they install cleanly and neatly which is why
Mass-Flo has them in their EFI kits.
The EFI harness provided by Mass-Flo includes pre-wired
relay and fuse block. These will be located underdash
and not in the engine bay. |
Every portion of the harness is marked for simple and
clear layout. |
The first step is to figure determine how much harness
you'll have in the engine compartment and how much will
be in the passenger compartment. Lay the harness over
the engine and temporarily connect to several injectors
and sensors. Route the harness as you plan to lay it out,
and clear of headers and other potential burn or cut obstacles.
|
Make note where approximately the harness will enter the
firewall. You'll need to then wrestle the supplied grommet
into the desired position on the harness. Getting the
grommet over larger connectors is made easier with the
use of silicone spray. |
The kit comes with several rolls of OEM style electrical
tape and split loom. Once we have the grommet in the desired
location we bring the harness over to the work bench and
begin wrapping. This is non-adhesive tape so pull tight
and overlap the previous turn to create a proper wrap.
|
We use a hole saw to drill the required 2-1/2" opening
for the harness pass through. This car has no heater and
a block of plate in place of the heater motor. We used
this as our grommet location. |
The harness is fed through to the engine bay from inside
the passenger compartment. Note that we've only wrapped
the main sections of harness that we won't be able to
cover once installed. |
After the harness is laid over the motor make the connections
to the injectors and sensors. You might have to peel back
some of the the harness to move connectors depending on
how you position your throttle body (IAC to the front
or back, for instance.) Once you've figured it out then
finish up the wrapping. |
It is critical to run a good ground in an EFI system.
A poor ground connection will cause all kinds of gremlins
in driveability and performance. We grounded using one
of the rear intake manifold bolts. |
Once the harness is laid out in the engine bay we focussed
on the under-dash wiring. We suggest pulling the seats
to make it easier on your body! |
From inside the car and under the passenger side dash
mounted the relay panel and fuse block. |
Shown are the connections which need to be made to get
the EFI system operating. The fuel pump power (pink) is
on relay and can go to directly power your pump. Note
the check engine light and EEC test port. |
The EEC-IV computer senses for a completed check engine
light circuit. The included light is also useful in troubleshooting,
so we mounted it in plain sight on the Mustang's center
dash panel. |
There are three power connections; the heavy red wire
from the fuse block goes straight to the battery positive
to give the computer constant power. The orange wire needs
to see 12V when the key is in the on position. The source
for this can be found in the wires behind the ignition
switch. The purple wire needs to have 12V from when the
starter cranks and engine is running. This can be located
at the starter relay. |
Since this car does not have a heater there was plenty
of space under the dash and behind the glove box to locate
our processor. We fabricated a steel plate with four stand-off's
to hold the A9L processor which we sourced separately.
The Mass-Flo cover makes mounting the unit very easy. |
Also on our under dash mounting location is our EEC test
port and the fuel pump inertia switch. This switch must
be mounted upright and will break the fuel pump circuit
upon sudden impact to the vehicle. This can prevent fuel
spillage and fire in the event of a collision. |
