ElmrPhD

Hi All,
Can anyone confidently answer this question for me? My aftermarket ECU (Omex 710) requires this to be answered before I can proceed.
Engine is out of a UK-spec' 2005 S2K.
Thanks!!!

Slowcrash_101

Stepper, PWM is for things like variable speed fans and the like. IACV is a rotary valve.

ElmrPhD

Trying to better-understand your reply, I kept digging.

My Omex manual suggests that stepper motor IAC valves have 4 wires, whereas the S2Ks have only 3 wires, which corresponds to solenoid-controlled valves.

I found that AEM describe the motor type of the S2K rotary valve as a, "Duty-controlled solenoid".
Then I found that solenoids can be PWM-driven. What I don't understand is if "duty-controlled" excludes PWM or if it can be the same as I know there is a relation between them. Apparently, the ECU rapidly grounds the circuit in "pulses", which obviously conjures up PWM, but that's about as far as my brain can take me.

These findings lead me to think that maybe the solenoid of the S2K IAC rotary valve is, indeed PWM-driven. What do you think?

If the IACV is PWM-driven, then Omex tell me that I must install 1 or 2 diodes in the circuit for some reason. Oh, joy.

Thanks.

Unbr3akable

It's my understanding too that Honda IAC valves use stepper motors BUT they are controlled by the ECU with a duty controlled PWM signal. The IAC valve must have an internal circuit (see below) that controls the stepper motor coils, how else would you control a stepper motor with 1-wire?

When I have time, I can hook up the IAC valve to a scope but I'm almost certain it's duty controlled with a PWM signal.

Caleb

flanders

Are you going to use Omex ITB's as well?

ElmrPhD

Hi Caleb,

Thanks a bunch for the effort to show useful images for my question. Very much appreciated.
However...the symbol that you show for "Stepper" is the symbol for a solenoid. What I don't know is if such a solenoid can function as a stepper. Or, more to my question, is it PWM controled? Is your red "PWM" label from a Honda source?
Also, the IACV connector has 3 wires. But I guess you are saying that the other 2 wires are simply 12V and ground, so there's only one control wire left. Correct?

Aha! I don't know how I missed this earlier, but from a fairly authoratative source, Hondata:

"The idle air control valve (IAC or EACV), which is located on the back of the intake manifold. The IAC valve is a solenoid which is controlled by the ECU using pulse width modulation. Thus the ECU can control how far the solenoid is open and how much air bypasses the throttle plate. There are limits, both upper and lower, to the amount of air which passes through the valve because the solenoid will only work from 20% to 80% duty cycle."

Ok, so in Omex's world, I'm gonna go with PWM- and not stepper-motor- driven. For some reason, that means I must insert a diode or two (don't ask me!), which I was really hoping to avoid...

Sorry for my ignorance in these matters. Be on the lookout for more...

Thanks for your help.

Steve, in the NLs
F20C-driven kitcar

Slowcrash_101

Where is it asking you to install diodes?

ElmrPhD

Between 12V+ and each of the other (2) wire(s). I have no idea why.
Again, this is for an aftermarket (Omex 710) ECU.
Thanks.