on a perfect running engine and idle controls work right, and idle control ISC is working
and you set the duty to 50% (using the bleed screw)
if the TPS idle switch is not closed at 0vdc there will be no idle controls.
The ECU must not be stuck in limp-home mode. ( no CEL codes stored or worse live errors)
The ISC must not be bad , stuck or jammed, or , leaking air closed or dead coil inside.
No huge illegal air leaks.
the bleed as set to 50 % dutycycle on the coil of the ISC, using scope or duty meter, 180f coolant is hot not 140f ever. the IAC closes at 150f so, that must happen first.
i made this drawing that shows all parts related to idle
![[Image: freshair-map.jpg]](https://fixkick.com/IDLE-AIR/more-photos/freshair-map.jpg)
the scope here is wrong, cold engine but the hot engine we turn the bleed until the ISC signal is 50/50 , high only 1/2 the time, 200 times second it pulses
![[Image: iac-wave1w.jpg]](https://fixkick.com/IDLE-AIR/Slide_Show/images/iac-wave1w.jpg)
vertical scale above is 5vdc per division, the alternator is active ad 14.7vdc so looks like 3 division at 15v. the IAS is Pulse width modulated, PWM.
and you set the duty to 50% (using the bleed screw)
if the TPS idle switch is not closed at 0vdc there will be no idle controls.
The ECU must not be stuck in limp-home mode. ( no CEL codes stored or worse live errors)
The ISC must not be bad , stuck or jammed, or , leaking air closed or dead coil inside.
No huge illegal air leaks.
the bleed as set to 50 % dutycycle on the coil of the ISC, using scope or duty meter, 180f coolant is hot not 140f ever. the IAC closes at 150f so, that must happen first.
i made this drawing that shows all parts related to idle
the scope here is wrong, cold engine but the hot engine we turn the bleed until the ISC signal is 50/50 , high only 1/2 the time, 200 times second it pulses
vertical scale above is 5vdc per division, the alternator is active ad 14.7vdc so looks like 3 division at 15v. the IAS is Pulse width modulated, PWM.
http://www.fixkick.com