(From the 2008 service manual)
The air induction system burns unburned exhaust gases by injecting fresh air (secondary air) into the exhaust port, reducing the emission of hydrocarbons. When there is negative pressure at the exhaust port, the reed valve opens, allowing secondary air to flow into the exhaust port. The required temperature for burning the un- burned exhaust gases is approximately 600 to 700 °C (1112 to 1292 °F)
Air cut-off valve
"The air cut-off valve is controlled by the signals from the ECU in accordance with the combustion conditions. Ordinarily, the air cut-off valve opens to allow the air to flow during idle and closes to cut-off the flow when the vehicle is being driven. However, if the engine temperatureis below the specified value, the air cut-off valve re- mains open and allows the air to flow into the exhaust pipe until the temperature becomes higher than the specified value."
Pretty much tells me the ECU should be in open loop (O2 sensors has no input) when ever the cut-off valve is open.
Warming up, idle, WOT
(I couldn't see having a negitive pressure situation at the exhaust port during this event), and decelerating. The mechanical reed valves will only open during the negative pressure event even tho the solinoid valve is open.