[Damo]

Does anyone know what frequency the idle control valve off the 1.6 16v engine operates at? Perhaps someone with access to factory stuff might know (Mr Steak?)

I have it set at 100Hz (running off the Megasquirt) at the moment but it is buzzing at lower duty cycles.

[royce]

I dont think its a frequency as such, more a duty cycle

ill try and measure mine

[Damo]

Thanks Royce.

According to some docs I have read they are supposed to read 50% duty cycle at idle. It would be good to know what duty cycle has the valve completely open and completely closed.

[royce]

0% duty cycle = completely closed
100% duty cycle = completely open

from memorey and only a brief fiddle with it at normal idle and AC off its not doing anything

[Fity]

The Suzuki manual says that it operates at 200 cycles per second or 200hz. Says nothing relating to the on state time, but I would guess 50% duty cycle would be a good place to start. Don't forget the idle screw (not the one which the butterfly stops against like a carby) can be used to change the duty cycle.

[Damo]

Fity wrote:

The Suzuki manual says that it operates at 200 cycles per second or 200hz. Says nothing relating to the on state time, but I would guess 50% duty cycle would be a good place to start. Don't forget the idle screw (not the one which the butterfly stops against like a carby) can be used to change the duty cycle.

Ta

[royce]

Fity wrote:

The Suzuki manual says that it operates at 200 cycles per second or 200hz. Says nothing relating to the on state time, but I would guess 50% duty cycle would be a good place to start. Don't forget the idle screw (not the one which the butterfly stops against like a carby) can be used to change the duty cycle.

How does the idle bleed change the duty cycle? I can adjsut my idle speed as high or low as I like with it and the ecu doesnt seem bothered in trying to control it at another point

[Damo]

royce wrote:

Fity wrote:

The Suzuki manual says that it operates at 200 cycles per second or 200hz. Says nothing relating to the on state time, but I would guess 50% duty cycle would be a good place to start. Don't forget the idle screw (not the one which the butterfly stops against like a carby) can be used to change the duty cycle.

How does the idle bleed change the duty cycle? I can adjsut my idle speed as high or low as I like with it and the ecu doesnt seem bothered in trying to control it at another point

AFAIK it doesn't, it's basically just an air leak.

[Fity]

From what I thought the IAC solenoid bypasses air around the butterfly to maintain the idle speed by the ECU. The Idle bleed screw does the same but is set to maintain duty cycle at idle with the AC off etc. The idle bleed screw will only alter the idle speed when the IAC duty cycle is at 100% or the IAC is stuck (they suffer from carbon build up over time)

Just found the reference to it in the manual. Basically it says to use a duty cycle meter and adjust to 50% using the idle bleed screw. Or you can also use a volt meter across the IAC and set to 1/2 battery volts (Measure your battery first as different alternators have different voltage regulation points)

[Damo]

Looks like 200Hz is working OK for me.

I'm setting up Megasquirt for closed loop idle control. Seems to be working pretty good! One trick is that the duty cycle value entered isn't the actual DC value. It's in the Megasquirt manual but I didn't realise until I read that bit, had me scratching my head!!

[mondo]

just out of curiosity, does this affect performance at all??

[steak_knife]

mondo wrote:

just out of curiosity, does this affect performance at all??

Of the idle, yes......