87-90 Mustang Turbo Swap Info

87-90 Mustang Turbo Swap Instructions
Thanks go to GT350R, SVO1, & Crovax - Authored by 140cilx, Formatted and Re-worded by Stinger

If you want a 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

1. Intro

This 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 BUT WANT TO RUN A TURBO ENGINE IN YOUR CAR: Our PiMPx ECU is completely programmable and allows you to run your factory ignition system/wiring with a turbo without doing any of the wiring changes listed on this page. If you want to skip all of these instructions and not have to buy the old 35 year old ECU, air meter, injectors, etc., all of which are limited to around 250hp anyway, while also upgrading to a modern and tunable ECU, you can use our PiMPx ECU and use the DIS (distributor ignition system) components on the turbo engine with the stock DIS harness. Our plug and play ECU's are listed here: Stinger ECU's   

This how-to only requires the use of a small portion of the Turbo Coupe harness (the vam plug and the coil plug). You DO NOT need the entire TC harness as you will be modifying the stock Mustang harness. We sell the VAM pigtail (two versions) here: Pigtails 

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 well.


2. How to Connect VAM Wiring

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.

Connect the 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.

3. ACT Wire Conversion

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.


4. 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 mode.


5. Closing Steps

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 www.boostvalve.com.

You 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:

If you 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 solenoid.

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 found HERE
 

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