Project STi Gets EcuTeK'd
Excperts from Modified Magazine, by Peter Tarach
With over a year of design and testing, EcuTek has probed the
US-Spec Subaru STiís ECU extracting all the necessary data to
be able to write/alter/control virtually any of the functions
found n the very complex ECU. Most important and of most interest
to us, is it can now access the fuel, ignition and timing maps
to tweak the factory settings into more aggressive settings resulting
in more ponies under the hood. For those that donít know, a reflash
isnít an ECU you bolt on or anything physical for that matter.
It is software that is flashed into the ECU via a laptop that
is connected to the carís OBD-II port and replaces the factory
ECU settings. Also, the EcuTeK software canít be accessed by
any Joe Shmoe either. A trained and certified EcuTeK dealer is
the only person that can alter the parameters.
Ben Dagenais arrived -- EcuTeKís head trainer for North America --
and our STi was loaded on to the rollers. Tuning was
about to commence. To get an accurate air/fuel ratio reading,
Ben quickly hooked up the Innovate wideband O2 sensor into the
exhaust then proceeded to plug his laptop into STiís OBD-II port.
With some quick keyboard strokes and a turn of the key in the
ignition, the stock STi fuel, ignition and timing maps were downloaded
and available for viewing. Ben looked at several of the maps
and noted that the stock map is very rich. The car is running
at about 9.5 to 1 AFR (Air/Fuel Ration) on the top end. Before
we went ahead with tuning the car, a base line pull was needed
to show before and after results. After making almost ten pulls
on the rollers, we decided that the median run would be used
as our baseline. The results 231whp and 278 lb-ft of torque!
The actual tuning began now that we had a base number to work
with. The first task was to remove some fuel. About 25 percent
of the fuel was taken out throughout the lower RPM range to 5,500rpm.
For the top end (5500rpm +) we wanted to keep things more conservative
and safe so only 20 percent of the fuel was removed. With a better-looking
AFR now in place, our search to unlock more trapped hp was on.
The simplest form of adding horsepower in a turbocharged car
is upping the boost. Knowing that the injectors were already
close to their operating limit and that the turbo couldnít feed
much more air into the motor (without grenading or causing an
extremely heated charged) we were very limited as to how much
more boost we could add. With Benís tuning expertise he knew
we could set the boost to 20psi in the lower part of the powerband
and taper it off to 14psi as the engine hit redline without any
ill effects. On the timing side of things we were able to add
a few degrees here and there in the powerband to squeeze out
the last remaining untapped ponies.
With the new EcuTeK tune in place the STi spun the rollers to
the tune of 270whp and 321 lb-ft of torque. Giddy up! Thatís
a gain of nearly 40whp and just a tad off 40 lb-ft of torque.
Of course many more urns were made to verify that this one pull
wasnít a fluke and they all came within 5whp each time. Armed
with more power and a lot of anticipation we hit the streets.
Seat of the pants reaction says, ďWow!Ē ďWhat a difference!Ē The
first and second gears used to be power gears but now with all
that torque in place the five, six gears pull just as strong
if not stronger. Luckily, we had the Rotora big brakes to quickly
slow us down from the insane speeds we reached during the testing.
Words cannot describe the overall improvement; itís a whole
new car. We are confident the car will take well to a bigger
turbo and supporting mods, which is already in motion.
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