VVT-i

VVT-i, or Variable Valve Timing with intelligence, is an automobile variable valve timing petrol engine technology manufactured by Toyota Group and used by brands Groupe PSA (Peugeot and Citroen), Toyota, Lexus, Scion, Daihatsu, Subaru, Aston Martin, Pontiac and Lotus Cars.

Variants of the system, including VVTL-i, Dual VVT-i, VVT-iE, VVT-iW and Valvematic have followed.

The engine head resembles a typical DOHC design, featuring separate cams for intake and exhaust with two intake and two exhaust valves (four total) per cylinder, but unlike a conventional design, each camshaft has two lobes per cylinder, one optimized for lower rpm operation and one optimized for high rpm operation, with higher lift and longer duration.

When the engine is operating above the lift engagement point, the ECU activates an oil pressure switch which pushes a sliding pin under the slipper-follower on each rocker arm.

Toyota has since ceased production of its VVTL-i engines in most markets because it does not meet Euro IV specifications for emissions regulations.

By adjusting the valve timing, engine start and stop occurs almost unnoticeably at minimum compression.

The benefit of the electric actuation is enhanced response and accuracy at low engine speeds and at lower temperatures as well as a greater total range of adjustment.

The combination of these factors allows more precise control, resulting in an improvement of both fuel economy, engine output and emissions performance.

VVT-iW (Variable Valve Timing - intelligent Wide) was introduced with the 2.0L turbocharged direct-injected 8AR-FTS fitted to the Lexus NX 200t.

This system is simpler in design compared to Valvetronic and VVEL, allowing the cylinder head to remain at the same height.

The D-4S system helps with providing more peak power at high rpms while also reducing emissions at the same time.

In 2010, Toyota USA announced a Limited Service Campaign (LSC 90K) to replace the rubber portion of the oil supply hose for the VVT-i actuator on the 2GR-FE (V6) engine, which were found to be defective.