CONVERTING YOUR SPEED
DENSITY 5.0 MUSTANG TO MASS AIR FLOW SYSTEM
Author: Mike Stowe
Mustang Mass Air Conversion
In this document, I will outline the steps to convert a speed density
mustang to the MAF system. I am generating this because I felt the
documentation I had to work with could be improved. This is based on my
own personal experience converting my 88LX convertible to MAF and the
instructions that came with the kit I bought. The color codes of the
wiring are what I saw in my car and may not be the same but probably are.
This document is for reference only and I accept no responsibility for
what you do to your car.
REQUIRED COMPONENTS: You will need to obtain a Mass Air meter, a MAF
computer and the electrical harness for the MAF meter. The meter harness
can be purchased from several manufacturers for about 50-60 dollars but
you can make your own if you wish. There are a few EEC's that can be used
depending on the car. I've heard it doesn't matter manual vs. auto tranny
but I don't know for sure so this is just some additional info for you.
For older MAF computers, the numbers are:
Manual transmission hard top:E9ZF 12A650 AA
Manual transmission convertible:E9ZF 12A650 BA
Automatic transimission:E9ZF 12A650 CA
For later (early 90's I think) MAF computers, the numbers are:
Automatic transimission:F3ZF 12A650 BA
Manual transmission:F3ZF 12A650 AA
Universal EEC:F3ZF 12A650 DA
You can also use the 93 cobra computer:F3ZF 12A650 CA but it requires MAF
calibrated for 24# injectors.
The MAF mounting bracket and associated plumbing between the throttle body
and the air filter box will have to be acquired from a junk yard or you
can rig up your own setup. If you intend the to do the "optional" signals
mentioned later, you'll also need to obtain 3 EEC connector pins and some
wire.
NOTES: Average mechanical skills are about all that is needed. The only
special skill I suggest you have to do this conversion is soldering. Crimp
connections are unreliable and could lead to future troubleshooting
headaches which you should avoid.
1. EEC REMOVAL
Before you begin, disconnect the battery. Remove the passenger side kick
panel. There is 1 screw and a push-in fastener that secure it. Remove the
screw in the white plastic retainer that holds the EEC in place. There was
a ground wire and a relay, each one screw that I had to move out of the
way so I could get the old EEC out. You should now be able to pull the EEC
down and out. Once the EEC is out, remove the EEC harness connector using
a 10mm socket to loosen the bolt in the center of the connector.
2. MAF HARNESS INSTALL
You'll need to run the 4 wire MAF meter harness through the fire wall on
the passenger side. I suggest you poke another hole in the large oval
grommet the existing EEC harness goes through located in the upper corner
on the passenger side of the firewall. I popped the grommet out of the
firewall with a screwdriver and used an exacto to poke a hole in the thin
section. You don't just want to blindly jam something through there
because you may cut the insulation on some of the wires and cause future
shorts. I then used a wire coat hanger as a snake, poking it through the
grommet and coming out by the EEC inside the car. I taped the MAF meter
harness to the snake (protecting the EEC pins) and pulled it through from
inside the car. Pop the grommet back into the firewall after the harness
has been pulled through. I then used some silicone to seal the area where
the new harness goes through the grommet so I didn't get any water leaks.
Remove the red "H" shaped plastic pin lock in the EEC connector. Gently
pry around the plastic pin lock with a pointed awl or small scewdriver
working it up and out of the connector. You can't add or remove EEC pins
to the connector without removing this lock. Depending on the MAF meter
you have, it may have a 4 or 5 pin connector. Refer below for pin
locations.
|
PIN |
5-Pin connector (E4FB 14489 BA) |
4-Pin connector (F078 14489
BA,E9DA 14489 BA) |
|
A |
Power (+) |
Power (+) |
|
B |
No connection |
Ground (-) |
|
C
|
Ground (-) |
Signal (-) |
|
D |
Signal (-) |
Signal (+) |
|
E |
Signal (+) |
|
a. The Power (+) wire from the MAF meter harness needs to be spliced into
the existing red wire in position #37 of the EEC connector.
b. The Ground (-) wire from the MAF meter harness needs to be spliced into
the existing black/green wire in position #40 or #60 of the EEC connector.
c. The Signal (-) wire from the MAF meter harness needs an EEC pin which
then gets inserted into position #9 of the EEC connector.
d. The Signal (+) wire from the MAF meter harness needs an EEC pin which
then gets inserted into position #50 of the EEC connector.
The locations for pin #9 and #50 should be empty. The pin numbers are
embossed into the plastic connector on the back of it where the pins
insert. It's a little hard to see but they are there if you look closely.
Please note that the notches shown in the diagram are not the ones seen
in the picture. The ones in the diagram are actually keys that only permit
the connector to be installed into the EEC one way. Pins 20,40, and 60 are
closest to you in the picture. It should be obvious because the pin
locations for the additional signals must be empty.
3. MAF METER INSTALL
Remove the existing air filter box cover and tube leading to the throttle
body. Install the MAF to the passenger side strut tower which should
already have the holes for the bracket. Connect the duct work, tighten the
clamps and connect the meter to the MAF meter harness.
4. THERMACTOR PUMP PIN MOVES
You will need to move the 2 signals for the thermactor pump to different
locations in the EEC connector. The EEC pins are held in place by a hook
shaped retainer that snaps into a groove in the EEC pin. To remove you
must pry the hook back from the EEC side of the connector and either push
on the pin or pull on the wire from the back. I used a paper clip and
flattened one end but a small jewelers screwdriver would work also. The
wire currently in position 51 tan/red needs to be moved to position 38.
The wire currently in position 11 green/black must be moved to position
32. If there is not enough slack for this to reach the new location,
you'll have to splice in some extra wire. Mine reached without doing this.
The next 2 steps some consider optional but will generate error codes in
the EEC. Others have reported stalling problems without the VSS signals.
In my opinion it's worth doing if only for piece of mind and no bogus
error codes. In preparation for these signals, remove the driver's seat
and the driver's side kick panel. There are 3 wires that will need to be
added for these signals with EEC pins on one end. I suggest you tie them
all together and route them as one cable over to the EEC on the passenger
side. I took this opportunity to change the carpet at the same time so I
had most of the interior out which made this fairly simple.
5. FUEL
PUMP MONITOR SIGNAL
This signal called FPM2 is used to monitor the voltage going to the
fuel pump. It will generate an error code in the EEC if it's not
connected but "shouldn't" cause a problem. Splice into one of the 2
pink/black wires going to the relay located under the driver's seat
and insert the other end into position 19 of the EEC connector. Refer
to figure 1. |
Figure 1 (Relay under driver's seat) |
6. VEHICLE SPEED SENSOR SIGNALS
These signals are required for cruise control and as stated earlier, some
have reported stalling problems on cars not equipped with cruise so avoid
the head-ache and just do it. These will also generate an error code in
the EEC if not installed. These signals come from a sensor that plugs into
the transmission. The easiest place to tap into them is behind the
driver's side kick panel. There is an 8 pin connector cable which runs
back to the driver's seat, across the floor under the seat then back
towards the front of the car and then goes through the transmission hump
to the sensor. You will need to splice into the orange/yellow wire. The
other end of this signal needs an EEC pin attached and this gets inserted
into the EEC connector into position 6. You need to splice into the dark
green/white wire for the other connection. The other end of this signal
needs an EEC pin attached and this gets inserted into the EEC connector
into position 3. Refer to figure 2.
Figure 2 (VSS signals behind driver's kick panel)
7. COMPUTER INSTALL
Put the red H shaped pin lock back into the EEC connector. Bolt the
connector to the new MAF EEC and slide the EEC back up in place. Install
the bolt for the EEC retaining bracket and any other relays/grounds you
may have removed to get the old EEC out.
8. MAP SENSOR
The manifold absolute pressure (MAP) sensor is located on the firewall
next to the vacuum tree. Disconnect the vacuum line from the sensor going
to the intake and plug the line going to the intake so you don't have a
vacuum leak. Leave the port on the sensor open and DO NOT disconnect the
electrical connection to the sensor.
MAP Sensor on firewall
Congratulations! You should now be done with your
MAF conversion. I suggest you re-check all your wiring changes at this
point before you re-connect the battery to avoid a smoke show of a
different sort. Once you are happy that everything is correct, re-connect
the battery and start the car. The car may idle a bit rough for a while
until it relearns, but severe idle or drivability problems may indicate a
real problem.
Author: Mike Stowe
