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Adaptive ECUs (EVO VIII)
As today's vehicle ECUs become more and more sophisticated, some OEMs have incorporated roadblocks to additional performance. One such vehicle taxed by this hurdle is the Mitsubishi EVO-VIII. The EVO-VIII computer knows when the engine has been modified to produce additional power. A map of the highest expected air flow meter readings versus engine speed are burned into the computer. When these values are exceeded because aftermarket parts have been placed on the vehicle, the factory ECU responds by reducing the boost levels until the air flow meter reads values at the stock performance levels. The result is that the car generates near factory horsepower levels even though high-performance aftermarket components have been placed on the vehicle. Another performance challenge on some newer vehicles is the existence of multiple fuel and ignition maps. The adaptive ECU switches between these maps when it finds that the O2-correction or knock readings have reached a certain level. This makes some new vehicles extremely difficult to dyno test for repeatable results as the ECU jumps between different fuel and ignition maps from run to run. These are some of the potential problems that can be encountered with today's adaptive ECIs, so what are some of the potential solutions?

Part of the solution with the EVO-VIII and any other turbocharged vehicle with an adaptive, performance-limiting ECU is to take away the control of the boost pressure by the ECU. By using an aftermarket boost controller (either manual or electronic), the factory ECU is not able to adjust boost pressure. We addressed this problem by installing an HKS EVC electronic boost controller on our EVO-VIII. To address the "map jumping" issue, we had two options. If we selected to run a high-octane fuel, such as 100-octane unleaded, we could have rested assured that the most aggressive timing map would be used by the ECU, since the knock count would have been very low. This solution had both pros and cons. On the pro side, the cost is rather insignificant. For less than a $100, we could have purchased enough fuel to perform all of the dyno work needed to test all of the exhaust systems. On the con side, using race gas would not have eliminated the factory ECU's ability to change fuel delivery and it wouldn't allow us to show the actual power output that could be expected on pump gas. The strategy we employed was to completely replace the factory ECU. This strategy provided three options; the A'PEX Integration Power FC, the AEM EMS or the HKS F-CON V Pro. We selected the HKS F-CON V Pro to gain some familiarity with this plug-in solution. XS Engineering started from scratch and mapped the F-CON V Pro for the EVO-VIII. This same and consistent mapping would be used throughout the exhaust test.

Our Test Vehicle
Our 2003 EVO-VIII was equipped with the aforementioned HKS FCON V-Pro and HKS Power Flow Intake. Straight from the pump, 91-octane gasoline was used for all of the testing. Boost pressure was set to 18 psi and regulated by an HKS EVC for the dyno pulls. All exhaust components from the exhaust manifold to the cat-back exhaust remained factory issue.

Our First and Last Turbo Exhaust Test?
This is our first and maybe our last exhaust shootout on a late-model, turbocharged vehicle. Much of the information that we are sharing with regards to the Mitsubishi ECU was learned first hand. When we started this test, we attempted to run the test as we had with other vehicles. Running the test with the factory ECU installed on pump gas would not let us obtain any repeatable horsepower figures. Unfortunately, a couple of exhaust manufacturers couldn't be represented in this test because their exhaust systems were tested before we isolated the problem with the factory ECU. The bottom line is that there are some really good exhaust systems available for the EVO-VIII that didn't make our test.

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