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Our ability to reprogram the ECU (Engine Control Unit/engine
management computer) for the SVX let's us retune the car for
performance, modify rev limiters, improve fuel economy, etc.
The memory adapter we've developed holds two versions of
software and is able to switch between them on the fly. The
latest version of the Stage One SVX package, Stage1Av1,
offers both improved performance and improved fuel economy
with the tune which runs by default. With the installation
of a simple spst switch or constant power connection the 2nd
tune provided with Stage1Av1 can be run with richer air to
fuel ratios for racing and nitrous oxide. Stage1Av1 is the
culmination of 6 years of SVX specific development and
replaces the previous version of SVX Stage 1 tuning,
Stage1v5.
With its orginal programming the SVX engine management
system uses a learning algorithm and knock sensor readings
to attempt to find the maximum ignition timing that can be
run without engine knock. A primary ignition advance table
specifies a minimum amount of ignition advance which allows
the car to run. An ignition advance revision table specifies
a maximum amount of additional ignition advance for the
learning algorithm to add to the base values of the primary
table. Previous versions of ECUtune tuning retained this
function; however, with the latest versions of ECUtune
software, called the "aggressive" versions, optimum ignition
advance is run by default and the knock sensors are only
used to decrease ignition advance if knock is detected.
Before release, the aggressive version was tested for over a
year with daily use by drivers with varying driving styles,
in SVXs in varying condition, and in regions with varying
driving conditions; in all cases impressive improvements
were realized with Stage1Av1.
The increase in actual igntion advance applied achieved with
the Stage1Av1 tuning results in both a performance gain and
a fuel economy gain. The fuel map in the default tuning of
Stage1Av1 improves fuel economy even further. The
intermittent hessitation under acceleration from a stop
common with the factory tuning is completely elimated. In
short the Stage1Av1 tuning provides smooth and responsive
power with better fuel economy and no hiccups.
The rev limiter has been raised to 7800 RPMs in the stage 1
software. With a stock transmission control unit the engine
will still never reach this rev limit; however, raising the
engine rev limit in the ECU allows us to modify the rev
limits in the TCU in order to increase the full throttle
shift points if desired.
Adjustments have also been made to the lower RPM portions of
the ignition table to improve performance if the SVX's
automatic transmission has been replaced with a manual
gearbox.Subaru SVX Stage One FAQ
Subaru SVX Stage One Photos
Subaru SVX Stage I installation Instructions
SVX Stage One is
only available for the OBDI Subaru SVX; 1992 through
1995 model years are OBDI. SVX's with OBDII ECU's,
model years 96 & 97, will not accept the memory
adaptor used for SVX Stage One. SVX Stage One
ships with the wire to connect to a spst switch and a
grommet for running the wire out of the ecu. An 8 page
instruction manual is provided online for download.
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