Originally Posted by
skyshack
AAC is pulse width modulated (PWM). It won't noticeably click on/off when on the car. It is held wide open on cranking and running off idle.
There are 2 types of AAC. Early type pushes a spring loaded plunger that has a cone in a brass hole in the idle control block. Late type has a tube with a small window that a plunger closes. The early type needs the whole idle block removing to clean properly, the plunger should be quite free.
Idle speed should drop when AAC is unplugged. Turn the hex head screw on rear of idle control, aim for 800 rpm.
Idle speed should increase with a surge and drop back to 850 rpm when AAC is plugged back in if unplugged while idling.
Check idle switch on front of TPS has continuity with throttle shut. Do a mode IV ECU check to verify it sees the idle switch open/close. Should open at about 1000 rpm.
Clean the throttle body / plate.
Try to wiggle the AFM plug, if rpm changes close down the terminals in the plug to make a better connection.