LA2 and LA3 swap into early SVO
 
For early turbo cars it is wise to add the stock location intercoolers from an SVO or Turbo Coupe, or go all out with a front mount. This will assist in fending of detonation due to fuel table and timing differences that take the cooler intake temps into consideration. It is recommended to move all pins even if you plan to use aftermarket boost controllers or you are swapping to a car that does not have the regular/premium switch. This part of the process only takes about 20 minutes depending on how hard it is to get the ECU out and back in to the inner fender. For turbo GT's you will need a big VAM. You will also need to run 35# low impedance injectors or as a temp solution up you fuel pressure to 43 PSI. You may want to go a bit farther and swap for a later upper and lower intake, but that is much more involved depending on the head in the car and is beyond the scope of this write-up. The instructions below are SVO specific, but with the changes mentioned is easily adapted to the earlier turbo cars.
 
If you are unsure about the wire locations please go to http://gt350r.stangnet.com/custom2.html and look up the diagram.
 
I used the instructions on svo1fast4's web site. His site is back up and I must appologise for taking so long to activate the link. Please take a few minutes to check out his web site where you will find 4 other very helpful how-to articles and much much more.
 
I made only one slight adjustment during my own install; moving the octane switch wire before the last two due to this being the most buried of the wires. I have included a pin chart for the stock 86 SVO harness from GT350R's web site, of which I used only the plug diagram to make sure I was in the right place. My SVO ECU plug was not numbered at all! It's not hard to tell where things are, as there is only one white wire with a black line 3 spots from the outer rows, so use that wire to get oriented and you'll be on your way. You can't really mess this up, but recheck your work after all the lines have been relocated and test the ECU before you bolt it back in.
 
Start:

Open your hood and unhook the battery positive cable. On the passenger side front, Remove the first screw in the carpet hold down trim and pull off
kick panel. Get out your 7mm socket and extension and remove the plastic bracket hold down bolt. Get out your 10mm socket and loosen the ECU harness plug bolt. This bolt does not come out of the plug. Pull the harness plug and other wires out of the way and remove the old ECU.
 
Remove the black wire guard. Flip the plug toward you and pull the red locking tab out. I used a small Allen wrench inserted into one of the unused holes and gently pulled it to the side to slide the locking tab free. The wires are in there pretty good, so they won't all pop free when you do this (I hope).
 
I used the same Allen wrench to push on the pins that needed to be changed, to work the wires free. Once they are loose, then you can pull them out from the back; some are in there really tight so this method means less of a risk in ripping the wire free from the crimp connector.
 

Now you are ready to begin the wire swapping.
 
Vane air temperature: Locate wire 43, white wire with a black stripe and move it into pin slot 27
 
Vane Air Flow sensor: Locate wire 25, light green wire with a purple stripe, and move it to pin slot 43
 
Octane Switch: Locate wire 30, yellow with red stripe, and move to pin #24
 
Boost controller (BCS): Locate wire 32, Purple, and move to pin #31
In the case of 84 SVO's you will need to disconnect the boost control module under the hood - not the solenoid - but the box it plugs into it a little lower on the passenger side fender. The PE's and LA3 ECU's have this control system built right in.
 
EGR Shutoff: Locate wire 35, yellow wire, and move to pin #33
 
ACT: This is optional. Many people running the 85.5 and 86 upper and lower intakes do not bother to tap a hole for this sensor. There is no proven benefit to drivability, MPG or health of the engine. My 84 runs perfect and puts out at least 220RWHP without it. If you are swapping for a TC lower intake, then the ACT bung is there and has to be filled anyway so it's up to you if you want to run the wires. I plan to do this swap myself and will post a blurb on it when I get to it.
 
If you are going to add the ACT, pin a wire to 25 long enough to run it behind the carpet or against the fire wall to the driver side and through the main wiring harness grommet and then tack on two feet. That should give you enough to rout it neatly to the sensor location in the lower intake.
 
Locate the black wire with a white stripe going to the throttle position sensor, water temp sensor or fuel injector harness and tap into that for the signal return.
 
Once you have moved all the wires, slide the red locking tab back into place. Make sure the wires you just moved don't get pushed out again during this step. Just pull slightly on them to make sure they are all secure. Replace the black wire guard and tighten the plug hold down bolt.

Test your work. Before putting the ECU back into the inner fender, start the car and make sure things are working. I recommend you make sure the ECU is sitting securely. Move everything from the floor and take the car out for a spin. Drive normal, test a bit of boost, but not too much, then if things are working good put it all back together and take it out for a good run. It may be wise to pick up a cheap A/F gauge. Just install it quick and dirty and look for the smooth max rich - max lean light pattern the signals things are working properly. A wide band test via Dyno is recommended.
 
Don't be too upset if you don't notice a difference in idle or performance the second you start and test the car. It will take a bit for the ECU to re-learn from its last application. My first install failed outright due to the use of a bad auto ECU. The LB series computers may be ok to use, but until I have a few to test I won't claim anything one way or the other. Once I put in the LA3, my car ran a little rough for about 1 minute. After that the idle smoothed out and that common SVO miss was gone. Upon the drive test, I sensed a power gain right across the RPM range and no more sulfur smell in the cat. The car started, idled and ran perfectly from that day on.

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