| 2005 Subaru WRX STi - Blitz Throttle Controller
Drive-by-wire systems, otherwise known as "electronic control throttle valve" units, are equipped in many newer vehicles. The ECTV units allow the ECU to control the opening and closing of the throttle body and make changes to the actual throttle position by sending multiple signals to quickly compensate for any change in air/fuel as well as engine temperature changes. Advantageously, the ECTV unit can adjust to driving characteristics compared to the more conventional cable driven style, which works independently on a spring-loaded throttle design, while the ECM is forced to play catch-up when throttling the car.
| The factory electronic throttle controller harness on our '05 WRX STI is located directly adjacent to the accelerator pedal.
While the engineering aspect of the ECTV-type design is a step in the right direction, the main drawback that's commonly associated with this new type of throttle unit is a slight hesitation and throttle response lag when hitting the accelerator or attempting to power shift through the gears. The initial pause or slow acceleration caused by these ECM-signaling ECTV-type units have been referred to as almost a mild turbo lag sensation in every gear-a nuance for vehicle owners and drivers. Alternative fixes to this problem can be resolved using aftermarket fuel management systems but the high costs of these units don't make purchasing them for this specific problem a logical choice.
| Remove the harness clip to gain access to the unit and install the new Blitz harness.
In a quest to combat this ongoing issue with ECTV-controlled vehicles and the unimpressionable lag that's associated, Blitz Japan released its newest throttle controller unit to the U.S. market with some promising results. The Blitz throttle controller works by piggybacking between the factory electronic throttle controller and the main Blitz unit. Using the provided harness, the throttle controller intercepts the pedal position sensor by taking the signal input and amplifying the output signal to trick the ECM into thinking the driver is pressing on the throttle harder than one actually is. The altered signal sent to the ECM is then relayed to the ECTV with belief that the driver is throttling at a high rate, which helps to improve throttle response and minimize ECM lag.
| Plug the Blitz harness into the factory throttle control unit harness.
With four mode settings-Eco, SP1, SP2, and SP3-offered on the Blitz throttle controller, the reaction of the accelerator pedal significantly changes from the milder "Economy" mode to a performance-orientated "Sport 3" setting. With a selection of each setting, the throttle plate is electronically altered to open at a larger increment at lower rpm. Comparisons to the throttle position without the Blitz Throttle Controller show the same throttle plate open at a smaller percentage when depressing the gas pedal at the same foot position.
| Be sure all the wires are properly installed before starting the vehicle.
The Blitz Throttle Controller shouldn't be confused with any standard boost controller or ECM piggyback fuel management system that offers an increase in horsepower. The throttle controller won't give you an additional 10 to 15 hp, as this unit was designed by Blitz engineers specifically to give your car faster acceleration while minimizing lag-something any ECTV sports car owner desperately craves in today's market.
| Clip the remaining Blitz harness into the main factory throttle control unit while taking the necessary steps to securely fasten the wires to minimize any interference when driving.
Economy
Using a graph to show the differences between the factory throttle position and the Blitz unit tested on all four modes, the X-axis represents accelerator while the Y-axis represents throttle. The "Eco" mode is used primarily to increase bottom end response. The graphs show the blue line indicating the Blitz controller has increased throttle till reaching the 30 percent marker where it automatically goes back to the factory settings in terms of throttle and acceleration. This is designed primarily for fuel economy/consumption to reduce the driver having to continually press on the throttle at different rates.
| We began testing the unit to see the variance in throttle position by turning the Blitz controller off while depressing the throttle position by turning the Blitz controller off while depressing the throttle to a consistent 1,500 rpm.
Sport 1
Blitz claims the "SP1" mode is a balance between fuel economy and throttle response. Throttle is opened greater at lower revs compared to factory settings and slightly higher than the "Eco" mode, providing increased acceleration at lower rpm and a slight variance in higher rpm.
| The most aggressive level, known as "SP3," quickly brought our tach needle to 5,100 rpm. Our STI's rpm quickly revved to the 5,000-plus rpm level with minimal pressure on the throttle accelerator.
Sport 2
The "SP2" graph shows a significant change in throttle compared to a stock throttle. The "SP2" setting increases the throttle ratio twice the rate of the SP1 setting, designed for sport driving and circuit use. From 0 to 100 percent, throttle characteristics through acceleration are increased dramatically.
Sport 3
Blitz engineers have labeled the most aggressive setting, known as "SP3," for extreme sport and circuit use. The throttle is opened at four times the standard accelerator position. Graphs show at 50 percent acceleration, the throttle at full engagement at 100 percent. Driving in this mode on the local streets and highways in traffic can be a daunting task since the car will have a tendency to lunge forward when clutching due to the rapid increase in rpm and throttle. This setting is ideal for track usage or quarter-mile sessions.
