Megasquirt
From Celica GT-Four / Alltrac - ST165 ST185 and ST205
Available Unit IDs: C01, C02, C03, C04, C05, C06, C07, S01, S02, V01, V02, V03.
Example: <google uid="C01"></google>, <google uid="C01" position="left" ></google>
Introduction
Megasquirt is an open-source, DIY engine management computer, or ECU. It has features that are more than capable of controlling your 3S-GTE to powers well in excess of stock by giving full control over timing, fueling, boost and many other items such as TVIS and fans. It should be noted that there are other options available for the Alltrac and Megasquirt is known to have bugs and other issues, please see the MS (Megasquirt ) forum for more information. Megasquirt is not for the "fit and forget" type, it takes a willingness to put time and effort in, not just wire up and go. If you want bolt-on performance look elsewhere. If you like experimenting with your car, tuning it yourself with your own gear and have a good idea of electronics and noise problems, the MS is as capable as the best of them.
How-To
Here I'll put my how-to writeup for installation on a '91 UK GT4, its currently available on my home site in a half-finished state.