MRT Performance - Subaru And Mitsubishi Performance Tuning Experts - Subaru propose an ECU update for MY08 STI

Subaru propose an ECU update for MY08 STI

Remember that you heard this first here.

In an unusual move, Subaru are proposing an update of the ECU ROM update for the MY08 STi. Subaru Australia generally don't make changes to the ECU ROM, indeed the only other times this has been done recently for turbo-charged Subaru's was for the Liberty B4s back in 2002 and the MY00 (Version 6) STis in 2000.

MY08 STi ECU ROM Comparison

As shown in the Main graphs below. ("Engine load" and "Accelerator angle") the ECU update makes changes to the mid range fueling (mildly richer) as the comes on the boost, and some minor changes around redline to reduce throttle opening before the car hits the rev limiter (effectively softening the impact of the rev limiter when hit).

The graph to the right is a summary where we use the EcuTeK "compare function" to list the basic differences between the "Old" rom file and the "new update file" that subaru will use.

The two small images below show the changes proposed to the boost settings at the fuel / rpm cut limits

Also, the changes make fuel cut (which occurs when either preset boost levels have been exceeded or RPM limiter has been hit) effectively last longer by halting fuel delivery (and therefore engine operation) until boost drops to a lower level (MAP levels shown in absolute levels, not more commonly quoted gauge pressure). In simple terms, previously as long as manifold pressure was below 24 Psi when fuel cut had been triggered, engine operation would resume within a few hundred milliseconds, now manifold pressure must be below 10 Psi. This is to prevent the driver banging the car off the rev limiter repeatedly, with the longer pause in engine resumption ensuring the engine is at much lower torque levels when operation resumes.

These changes are designed to rectify some issues that have been mainly experienced by some MY08 STis that are seeing track time.

MY08 STi Enhanced ROM - fuel cut resume changes

As you can see, MRT have the ability here in Australia to diagnose and modify the factory ECU ROM file and by converting the ECU (electronically) into a fully adjustable ECU, we can see what your ecu does and the settings Subaru chose at the time of manufacture.

Subaru have now released the revised ECU ROM to dealers, and are updating cars as they appear for service. We are not sure if they will release an official letter to ask cleints to present their cars to dealers. But as we know about the upcoming changes, all new EcuTeK tunes for the MY08 STi will now incorporate these enhancements, thus giving our clients better performance, fuel economy PLUS reliability!

So if you want to take advantage of this incredible technology and see why thousands of other owners in Australia and around the world (including companeis such as ProDrive) use EcuteK, contact MRT or one of our partners or resellers today.

Visit the MRT Power kit pages here and find out how you can modify your car AND keep the warranty.

We have updates for all Turbo Subaru's from MY99 onwards, plus and some non turbo 3.0L models.

MY08 STi Enhanced ROM - AFR changes

MY08 STi Enhanced ROM - fuel cut changes

Brett Middleton
		About the author:
		Brett is the founder of MRT Performance and the Middleton Rally Team and is married to Lisette with 3 children - Hayley, Oscar and Zac. Brett is responsible for client liaison as well as the usual financial control of the business, and also spends much time sharing his knowledge and passion of enhancing cars via interviews, books, tech nights and track days. In his spare time, he rallies in MRT's Honda Civic VTI-R. His daily drive is MRT's R&D Evo X.
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Last Updated ( Saturday, 14 March 2009 )

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