DIY_EFI Digest V5 #52

[Scott_Hay at toyota.com]

Adrian wrote:

"Here's a good web-page explaining Variable Valve Timing, and comparing the
Honda and Toyota methods.
The Toyota VVT you describe above has been superceded by TVVTiL, which is
the same system (the VVT bit) but has "intelligence" (the i bit) that means
it now has infinately variable timing, rather than just "mode A or mode B",
and also variable lift (the L bit) which means it adjusts lift as well as
timing."

Let me elaborate:  The "i" does stand for intelligence and yes it is infinitely
variable.  The intelligence means that it has adaptive learning abilities with a
feedback loop to match commanded valve timing to actual operating timing and
will adjust for wear, etc.  The link shows one system.  There is also a vane
type of VVTi now used  on the V6's.  One of the other benefits it that it
eliminates the egr system which is now accomplished through overlap.

Scott


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