VVT-i has nothing to do with injection. I believe the "i" stands for intelligent. My understanding is that VVT-i (which is a Variable Valve Timing system) works sort of like VTEC but w/o two different cam profiles. VTEC has two separate lobe profiles on a single camshaft. At a certain RPM it switches over to the more aggressive cam profile... and then you have high RPM power.
VVT-i is a variable cam timing system that varies the advance and retard of the cam relative to the needs of the engine at that time. So, instead of having two different cam profiles, it just advances/retards the existing camshaft a fixed number of increments depending upon what is optimum for the engine load.
Again, this is my understanding of the system, I welcome any corrections.
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