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Full details on the types of Toyota IACVs can be found here:
http://www.autoshop101.com/forms/h60.pdf == Stepper ISCV ==
== 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. |
| The early type is a simple solanoid which allows a vaccum to pass to a set of bellows that move against the throttle plate stop. |
| The newer 20v engines have a two coil IAC (marked as A in this diagram) |
| The newer 20v engines have a Dual-Control Rotary Solanoid IAC System, marked as A on the picture below. |
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A simple solution is to use a Relay to ground one coil or the other
In order to PWM the solanoid for the best results a FET driver with one inverting and one non-inverting output (such as the TC4428) may be used:
---- I guess it's very similar to the ones on BMWs (dual solenoid) with an extra pre-set spring. However selecting the dual-solenoid iac option in newer (>1.0.30) firmwares might control this valve without extra electronics. |
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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: <code> 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 </code> |