87-90 Mustang Turbo Swap Info
87-90 Mustang Turbo Swap Instructions
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Formatted and Re-worded by
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printable checklist while you are doing the swap, left-click or
right-click/save-as here (note that printable version may not always be up
to date with what is below):
Turbo Swap Instructions
is specific to the '87-90 LX cars receiving the '87-88 TC computer and VAM
harness ONLY. If you insist on running a different ecu (83-86 TC, SVO,
Merkur, ect) then you'll have to modify the wiring accordingly. An 87-88
ECU is only $50-75 though and is a much more capable ecu so I suggest
you just purchase one of you don't have one. Be sure you also have a big
vam (3" in/out) and 35lb fuel injectors (brown tops) to go with it.
If you don't want to do any wiring changes, our PiMPx ECU is for you.
This how-to only requires the use of a small portion of the Turbo Coupe
harness (the vam plug). You DO NOT need the entire TC harness as you
will be modifying the stock Mustang harness.
These notes are for a 5speed car only, but should be close if you wanted
to do an auto trans conversion. (who would do that)?
First off try to use as many pieces as possible from an 87-88 Turbo Coupe,
as it will simplify the conversion process. You do not need the whole
wiring harness from the t-bird, only the VAM harness connector. DO NOT
remove the harness from the Mustang.
Read this article carefully and you should be set on how to wire the
conversion. if you do not understand something feel free to study that
area until you do understand. If you do not you could end up messing up
something that could be costly to repair.
Also feel free to email me with any questions, or if you find any errors
in this article. I will not accept responsibility for anything you might
fry in the process of doing this swap. I advise researching all the wiring
diagrams and EEC IV info you can get your hands on.
I am not going to explain how to remove and install pins from a connector,
if you can't figure it out you might not want to do this swap. I will
give you a hint though, a small screwdriver or small razor knife works
to Connect VAM Wiring
||EGR Wires Cut
and Used for Vam
Strip, Vane Air Temp----------->>>
||Dark Green from EGR
So in text form, you
cut the 3 wires at the EGR plug and connect them to the wires you cut
form the Turbo Coupe harness for the VAM. You connect the VAM wires to
the former EGR wires running into the harness, not the short remaining
wires coming out of the EGR plug that you cut off.
Orange/White from EGR to the Orange/White from VAM.
Connect the Brown/Light Green wire from EGR to the White/Black from VAM.
Connect the Black/White wire from EGR to the Black/White from VAM.
The fourth VAM
wire is Light Green/Purple and it gets connected to the EGR Vent
Solenoid Dark Green wire (solenoid is located near the back side of the
passenger side strut tower). The EGR Vent Solenoid has a two wire plug
(Dark Green and Red wires). You simply cut the Green wire and connect it
to the Light Green/Purple VAM wire. You then move the Dark Green wire
from Pin 33 at the ECU to pin 43 at the ECU.
No changes necessary. The ACT wire is already going to pin 25 (green/red). This
means it's a direct swap in this regard with not wiring changes needed
for proper ACT sensor function.
Premium Mode Wiring
Cut the wire going into pin 24 of the LX harness about 5” above the
wiring block. This is an Air Conditioning Wire. The Air Conditioning will
still work properly with this wire cut and capped – this was an idle
increase control wire for the A/C. The 5” section of wire remaining,
going into the computer is your pin 24 octane control. Take this wire and “T”
this into pin 46 (signal return) or if you don't want to mess with pin 46
wiring, just ground the pin 24 wire to the chassis or use a toggle
switch to ground it. This will complete the connection and
allow your computer to run in the “High Octane” setting when grounded. You
must from this point on, run 91 or greater octane fuel when in premium
Unplug the vacuum
hose going to your MAP sensor and leave it unplugged on the MAP, then cap
the vacuum tree port where the vacuum line plugged into the vacuum tree.
The above information does not include wiring in the Electronic (computer)
Boost Control, so you will need to add a preferred (for greater boost)
adjustable boost valve, ignoring computer control of boost. I prefer the
Gillis valve found at
should use the Mustang injector harness. The TC harness has some
more wires integrated into it and complicates the swap. Make sure
you use the TC injectors though. They are not interchangeable.
6. Auto Trans Info:
have an auto transmission in your 87-90 Mustang and want to use it with
the turbo engine (which is a bad idea in my opinion because the trans is
weak and you'll kill it if you anything over stock turbo hp), then here
is some info for you. You'll need to make sure your 87-88 Turbo
Coupe ecu also comes from an auto trans car.
Pin 37/57 (VPWR)
provides power (+) to the 3/4 shift solenoid and the converter lockup
Pin 42 (3/4 shift)
When the computer grounds this pin, the 3/4 shift is enabled provided
that the transmission speed is sufficient to use overdrive.
Pin 53 (CCO)
When the computer grounds this pin, torque converter clutch is allowed
to lock up. To prevent a rough feel, the coverter lockup is inhibited at
certain speed upshifts and downshifts, brake on, cold engine, etc.
The above three connections terminate at a single 3 contact connector
mounted on the transmission.
Pin 3 (VSSDIF+)
One terminal of the vehicle speed sensor.
Pin 6 (VSSDIF-)
Other terminal of the vehicle speed sensor.
The two connections above terminate at the two terminal connector of the
vehicle speed sensor mounted on the transmission at the conventional
speedometer cable location.
So, that should be pretty straightforward wiring it up. Looking at the
Ford manual for the A4LD and the wiring diagrams, it appears that having
all this unhooked would just result in a 3 speed automatic (no
overdrived, no lockup clutch on the torque converter.) So unless the
transmission has some preexisting problem I wouldn't think it would
cause any problems to operate it disconnected. But for best fuel economy
and to lower overall engine RPMs most of us would like to have it all
fully functional as intended so it will shift into overdrive.
7. Helpful Info:
Step-by-Step Engine Swap Instructions can be
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