Why EcuTek? Part 2

In this part of the series on Why EcuTek? We would like to highlight and single out the advantages of Engine Management tuning on the Subaru STi using EcuTek Reflash software.

The STi major drawback is very poor performance at low RPM and “off boost”. This is due primarily to largish turbo, restrictive intake/exhaust and ECU base maps. The car is also detuned compared to the earlier MY99/00 STi models, with only 265bhp on tap. The extra weight of the MY01 onwards chassis also adds to the issue.

Luckily more power from this setup is not hard to obtain at all! Downside is that the fuel pump is barely capable of handling the standard engines requirements, and ANY change in exhaust without corresponding changes to ECU or boost control risk engine damage due to massive boost spikes in the mid range.

Besides the normal tuning variables like Fuelling, Ignition timing and Boost in EcuTek that can be adjusted to make more reliable power. The next mechanical enhancement feature within the STi is: AVCS (Active Valve Control System).

The highlight of this write out is to emphasize what Subaru employs on the late models’ STi - AVCS. It’s there for a purpose! With careful calibration and tuning, as much as 10-15% more horse power could be attained. (Best results depend on exhaust setup and turbo choice)

Therefore, STi owners out shopping for your EM needs do consider strongly on this point! You have a “tool” to make more power. Use it! Don’t listen when the shop says xxx system can’t control it and the AVCS is of no use.

Dyno plot shown is MY04 STI. Performance parts added are:

1.IHI vf37 Twin-scroll turbo

2.HKS EVC Boost Controller running 1.35bar peak

3.Stock air box with ram cold air intake

4.Perrin silicone turbo intake hose

5.Uppipe and TBE

6.HKS Legamax muffler

7.Upgraded fuel pump

8.Tuned with 98RON fuel

9.Remapped by EcuTek software. AVCS timing figures vastly different from stock!

** Launch Control Function enabled and set to launch at 5500rpm.