LA3 swap

[rfb92345]

Performance of '84 SVO was FUBAR. Did the LA3 swap today and wow, what a difference. I highly recommend it to everyone. I did notice that even though it had more power, it was making less boost. This is a good thing, but I don't know why. Any comments?

[SVOeric]

the computer should not directly affect your boost--- however --

the 84 uses a seperate boost controler module, that does connect to the EEC, but the LA3 is not setup for this type of boost controler--

you should un-plug the stock boost controler, and use some type of aftermarket controler, or get a boost controler for a 87-88 t-bird (the car the la3 came out of)

To be honest, I'm supprised the la3 even made the boost controler work at all....

Did you also chance injectors when you changed the computer?

[rfb92345]

We are going to install an aftermarket controller. Yes we did change injectors. We did not try the switch, so it may very well not work. We just noticed that the boost wasn't as high as with the old computer.

[Eyelawdoc]

Boost Lower with LA 3

Without the proper boost controller for the LA3 or an aftermarket boost controller, the boost will stop at 10 psi. Good to hear the swap went well and you are getting more power. Just wait till you get the boost levels back up again!

[rfb92345]

How high do we dare go on boost and what would be the nxt step? Maybe an Accufab regulator? By the way, another question, does an 84 SVO have a knock sensor and where is it? We have found a sensor on the bottom of the intake that was unplugged and we were wondering what it was. Thanks for all the comments.

[SVOeric]

yes -- 84 does have a knock sensor .. it should be in the lower intake, pointing towards the firewall.

boost is up to you -- 18 seems to be a good street number--
relilable, and still pretty peppy

What are your plans for the car, and maybe we can give you a better idea

[Eyelawdoc]

84 Knock Sensor

The sensor on the bottom of the lower intake manifold sounds like the knock sensor. I would recommend reconnecting it, especially if you increase the boost.

[rfb92345]

We reconnected the knock sensor and found it to be bad. We replaced it and everything is good now. The car will be a daily driver. We want to get the power up a bit and then concentrate on the handling.
We have another turbo motor, that we built, that is in an '88 turbo coupe. We were working the bugs out of it before it was reared and totaled. We want to try to find another SVO, with maybe a lunched drivetrain, and transfer all the good stuff from the TC to the SVO. That car had the ported big valve head, cam, ported intake, 65mm TB, 52# injectors, T3/T4, SDS, C4, etc. If we can smog it here in CA (ha ha) we'll drive it on the street, but we probably won't be able to, so well just run it on the track. We never really got all the power out of that engine, before the wreck, so it will be fun to see what it does once it is sorted out.
The SVO we have is a nice car and we want to keep it close to stock,..............sorta.

[StangerJon]

what do you have to change to get the La3 to work? is it just the large VAM and 35# injectors. or can i use it with the svo VAM? already have the 35# injectors.

[SVOeric]

the SVO already has the large VAM -- so that doesn't need to be changed

other than the injectors;
There are only a couple of wiring changes -- not too dificult

GT350 has been gracious enough to post the details of this swap on his site. here is the link.

http://ourworld.cs.com/_ht_a/cobra30197/svo/la3/la3.html?mtbrand=CS_US

I am most likely going to be doing this swap to my 85 in the coming weeks, I will try to do a write-up of my own on it.

EDIT :: Oh yea--- the LA3 will also have a place for a ACT sensor (a new sensor to add to the lower intake -- Air charge temp) -- this can be added, but some people are running without them, and making pretty decent numbers!

[Pat_in_L.A.]

Eric, I too will be doing an LA3 swap soon. The above link from GT350R was a great help. He also has pinouts and wiring diagrams on his site.

Other notes I have made but need to clarify:

1) Add a wire from #2 of ECU harness connector to Brake on/off (BOO) signal (stoplight switch).

2) Add a wire at #34 to VSS (Vehicle Speed Sensor). Lew mentioned that even better fuel economy can be gained by adding this. What I need to find out here is if the other VSS wire goes to chassis ground or feeds back to the ECU via the signal return(black w/ white stripe), such as has to be done with the ACT addition. Also, which year Mustang to rob at the yard of a speedo cable with VSS and loom plug (88-89?).

[GAboySVO]

Stangerjon,

If you have an 85 1/2 SVO, then you already have the best computer setup. The 85 1/2 SVO was tuned to produce the most HP of all years. I don't think you would gain much by changing the computer to the LA3.

[svobud]

I did the swap on my 85. Did not add an ACT. Only swapped the 4 pins as noted on GT305R's site.

I did see a decrease in gas mileage on the hwy - from 26mpg to 22mpg. I saw a jump in HP but even more so in TQ.

Only two things needed when doing the swap - the computer and the injectors.

[SVOeric]

hey Pat

I pulled up a wiring diagram for the 87-88 TC, and guess what, it shows NO CONNECTION on pin 34!!! -- I'll look to see if I can find another one.

I'm betting that one wire is ground

the stop circuit (pin #2) shows 1 wire, with no conenction to the sig-return -- Just spice it into the brake switch on the peda. -- check it with a volt meter, one side will read +12V, the other side will read nothing (with the brake off). Connect it to the side that reads nothing

BTW::: both these are optional --
the stop pin is probably to bump the idle a bit when you hit the brakes so the engine don't die (or bring it down from fast idle)

the VSS is to help the computer figure out what type of driving you are doing -- to help with fuel economy.
(both the above are my slightly educated guesses )

[Pat_in_L.A.]

Thanks Mike and Bud. The 88 TC EEC schematic only showed one wire going to a plug for #34, and didn't cover the signal return. I just helped someone with a messed up sigret rewire this month so I know which one to tap into from the VSS. As for adding the ACT, it looks like the nearest Black wire with white stripe will complete that circuit. That's a common to most all the sensors in that area.

EDIT (after Eric's last post)
Here's 88 TC schematic that I was looking at:

http://www.angelfire.com/pa3/turbocoupe/TC_wiring_diagram.jpg

And here are pinouts for all the Turbos:

http://www.gt350mustang.com/eecspecsturbo.htm

I imagine the rest of the puzzle is in the chassis loom diagram. Maybe I can talk Eyelawdoc into doing the breakout box thing on his T-Bird some day when he's not busy. (Oh, that's right! He's never not busy, LOL!)