The VVT-equipped Miatas are the 2001-2005 NB2 (BP with VVT) and the 2006-2015 NC (LF-VE, badged S-VT). Both vary intake-cam timing with an oil-fed phaser, and both live or die on clean oil.
How it works: an oil control valve (OCV) feeds pressurized oil to a phaser on the intake cam. The ECU advances the intake cam at low and mid rpm for torque and retards it up top and at idle for breathing and emissions
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