VehicleFitment/Toyota/IdleAirController

Idle Air Control

Full details on the types of Toyota IACVs can be found here:

http://www.autoshop101.com/forms/h60.pdf

Stepper ISCV

FI_106.gif

FI_107.gif

Two coil ISCV

The early type is a simple solanoid, called a Vacuum Switching Valve, which allows a vaccum to pass to a set of bellows that move against the throttle plate stop. They are triggered by ECU, or various electrical load switches.

Most people remove these when going to a stand-alone system, as they do not work very well after 25years of service.

The newer 20v engines have a Dual-Control Rotary Solanoid IAC System, marked as A on the picture below.

4AQuestion.jpg

One coil opens the IAC valve, the other closes it, with neither coil active the IAC valve sits at 50%.

The document states:

''The ECM controls IACV positioning by applying a duty cycled signal to the two electrical coils in the IACV.

By changing the duty ratio (on time versus off time), a change in the magnetic field causes the valve to rotate.

Basically, as duty ratio drops belpw 50%, the valve closes the passage. If the IACV is disconnected or inoperative,

the valve will move to a default position and idle rpm will be around 1000 to 1200rpm at operating temperature.''

The Solution

Thanks to the new Dual IAC firmware (1.0.30 on) and MembersPage/Skassa the Dual-Control Rotary Solanoid is now controlled correctly by VEMS. The following config values were used:

iac_conf=78
iac_max_steps=FF
iac_tps_thres=08
iac_cold_idle_temp=A2
iac_warm_idle_temp=B4
iac_cold_rpm=96
iac_warm_rpm=82
iac_cold_start_pos=80
iac_warm_start_pos=66
iac_afterstart_rpm=23
iac_afterstart_duration=A0
iac_speed=06
iac_kp=6E
iac_ki=03
iac_kd=FF