Quote:
Originally Posted by Isaac Zachary
Oh ok! I get what you're saying now. EGR would affect manifold air pressure, but so would timing.
On my Avalon when warming up it will retard considerably, like 25° after (not before) TDC. The throttle has to open up much wider and increases manifold pressure (less vacuum) quite a bit. This of course uses a lot more fuel, but that's the point. It does it to heat up the catalytic converter and rest of the engine more quickly. The interesting thing is idle engine speeds can be nearly the same in this more-open-throttle, retarded-timing state as it is when the engine is warmed up and the throttle closes and timing advances back to normal.
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One thing I've wondered - most Toyota engines use offset cranks, and I'd be shocked if this were not true of the Avalon hybrid's. So, 0° on the crank is not the same as top dead center for the piston. Additionally, I'm unsure if Toyota's "0°" is the same as Honda's, or anyone else's. Is it 0° relative to the minimum advance, or 0° relative to TDC, or 0° relative to the crank?