From FSM:
"Bypass Air Control (BAC) Valve -- Supplies bypass air into dynamic chamber -- Controlled by duty signal from control unit"
"Air Bypass Solenoid Valve -- Supplies bypass air into primary intake manifold -- Assist of BAC valve during cold condition"

Does the BAC just not supply enough air during cold conditions at idle?
Does someone know exactly how they operate together, such as the certain conditions where the Air Solenoid clicks on, or is it always on, and it clicks off sometimes?

I see that they both supply air to within 2 cm of each other in the primary DC port.

 

The BAC valve takes care of idle speed control. It increases idle speed to compensate for accessory loads on the engine. It's also held fully open during cranking to aid starting.

The Air Bypass Solenoid Valve and the BAC valve are both held fully open immediately after cold starts, and together they cause the 3000rpm idle to heat of the pre-cat (Accelerated Warm-up System).

The Air Bypass Solenoid Valve is not needed for cold starts, it's just to reduce emissions by getting the pre-cat up to light-off temp quicker. This function only lasts for ~15 seconds.

 

mines doesnt have it..and i have to hold the throttle at cold starts for a couple of mintues before it can stay on.
would my problem have to be with that

 

Thanks for the info NZ.

 

No, sounds more like the thermowax has been pulled off the TB.