Originally Posted By: Drew99GT
VVTI is the variable cam timing on Toyota's; there's a little actuator, at least on the Corolla's, on the intake cam that's actuated via pressurized oil, and it allows the intake cam gear to move forward and back independent of the camshaft, to change valve timing. Helps with fuel mileage and low rpm throttle response. Thick oil can't pressurize the activator enough to activate it.
The same phenomenon can happen with hydraulically activated timing chain tensioners.
Wouldn't thick oil pressurize it better? Thicker oil = higher oil pressure. Seems like, based on what you said, that the reason thick oil won't activate it is that the oil pressure must get LOW enough, because that would be the best way to tell if the engine oil was warmed up. That is... if you use the oil that the manufacturer recommends.
It just made me curious because it doesn't make sense to me. I am interested to know how it works.
VVTI is the variable cam timing on Toyota's; there's a little actuator, at least on the Corolla's, on the intake cam that's actuated via pressurized oil, and it allows the intake cam gear to move forward and back independent of the camshaft, to change valve timing. Helps with fuel mileage and low rpm throttle response. Thick oil can't pressurize the activator enough to activate it.
The same phenomenon can happen with hydraulically activated timing chain tensioners.
Wouldn't thick oil pressurize it better? Thicker oil = higher oil pressure. Seems like, based on what you said, that the reason thick oil won't activate it is that the oil pressure must get LOW enough, because that would be the best way to tell if the engine oil was warmed up. That is... if you use the oil that the manufacturer recommends.
It just made me curious because it doesn't make sense to me. I am interested to know how it works.
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