Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
VTEC/Variable Cylinder Management (VCM): Construction: Notes
The VTEC on this vehicle is used for switching intake valve lift between low lift and high lift, depending on engine speed and vehicle speed; it uses a variable cylinder management (VCM) system that switches the operating cylinder. Depending on the driving conditions, the VCM system switches between 6 cylinder operation and 3 cylinder operation. This mechanism allows driving torque to increase at the time of low speed and low load, improved fuel consumption, exhaust gas reduction, and higher engine performance at high speed and high load. The VTEC installed for each bank stops opening and closing the intake and exhaust valves on the rear bank when the 3 cylinder mode is activated. Not opening and closing the valves eliminates the drive resistance (valve spring compression resistance) for valve opening, closing and the suction air resistance (pumping loss), which leads to a reduction of engine rotation resistance.
Use the Manual With the Right Hardware
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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