How to Adjust a VTEC Engagementby Eric Strauss
Honda's VTEC engine -- which stands for Variable Valve Timing and Lift Electronic Control -- was produced for both usability at everyday speeds and high-performance capabilities, adding a second rocker arm and cam profile to the valve train. At higher speeds, the second rocker arm engages, which opens the valves wider for stronger performance. At lower speeds, the second arm does not engage, so the valves open in a more traditional fashion. In today's Hondas, which often utilize what are called i-VTEC (intelligent VTEC) engines, the engine computer or control unit (the ECU) regulates the timing of the cam. A Honda driver who wants to adjust the engagement point of the second rocker arm has a few options for manipulating the ECU's stock timing.
Ensure your Honda is capable of being "tuned" properly and can benefit from a VTEC engagement-point adjustment. This may necessitate the addition of aftermarket parts or other upgrades from the manufacturers' "stock" engine. As the Turbo & High-Tech Performance website states, "A bone-stock VTEC engine with stock cams and factory exhaust will show little if any increase in power from tuning." A driver seeking to modify her VTEC engagement points may benefit from swapping out parts, such as the intake and cams.
Reflash your engine computer. This is likely the least intrusive way of changing the VTEC engagement point, as it does not involve any additional engine hardware. Instead, the flash-based, on-board computer software is essentially reprogrammed. The reflashing might include lowering the RPM level at which the VTEC engages the second cam, which means the valves will open wider, sooner, and can add as much as 30 horsepower to the engine.
Add a fuel controller or computer to your engine. If reflashing does not achieve his goals, a driver can install this device. It does not replace the ECU, but works in conjunction, enabling the driver to adjust both the fuel curve and the various VTEC engagement points. By altering the settings, he can prevent premature engagement of the second cam at too-low RPMs -- and the resulting undesirable power dip.
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