Dennis,

Thanks for that comment. It better explains things I never quite
understood about "Dwell".

John

On 11/16/2013 10:37 AM, Dennis Haynes wrote:
> As with many digital control circuits, things are not modulated but rather
> turned on or foo with the "on time" or ratio of on to off time achieving the
> required results. The injectors are the primary example of this. They turn
> on once every engine revolution. The ECU changes the length of this "open
> time" to control the fuel delivered. If they were on all the time the duty
> cycle or pulse would 100%. Thing of dwell back in the ignition points days.
> There we used the angle to set the points. The longer the dwell, the better
> the coil could charge before we opened the circuit to make the spark.
>
> Dennis
>
> -----Original Message-----
> From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
> JRodgers
> Sent: Saturday, November 16, 2013 11:13 AM
> To: vanagon@GERRY.VANAGON.COM
> Subject: Re: Arduino and Vanagons
>
> Uh, I seemed to have missed something in this discussion What is a/the PWM?
> It just doesn't come to me.
>
> Thanks,
>
> John
>
> On 11/15/2013 10:03 PM, Brett Ne wrote:
>> GoWesty emailed back and declined to share their information, citing
>> "that data is proprietary".  It really isn't, just as knowing the
>> expected output voltage range of a healthy voltage regulator isn't
>> proprietary.  Oh, well, it was worth a try...it just means a little more
> work on our part.
>>
>>
>> So, here's what we need to know:
>> * The PWM duty cycle being feed to the idle air valve when:
>>        --the engine is cold, the starter is engaged, and the coil is
> shorted
>>        --the engine is cold & running
>>        --the engine is fully warm & running
>>        --the engine is fully warm & running with PS operating
>>        --the engine is fully warm & running with AC on
>>        --the engine is fully warm & running with PS operating and AC on
>> *  The current draw from the idle air valve at a known duty cycle.(or
>> feed it straight 12v and measure the current draw.)
>> * The base voltage and the peak voltage coming from the Hall sensor
>> The above items will need to be done by someone with a scope and a
>> healthy ICU & idle air valve(and PS & AC).
>>
>> *  Which connector, 4/ST2 or 11/ST1, supplies the PWM power to the
>> idle air valve. (and confirm that whichever supplies the PWM power,
>> that the other is a ground connection.)
>> *  What is the voltage at the coolant temperature sensor when cold and
>> when
>> 160 F.
>>
>> I think that this would provide all the information needed to design
>> the circuitry and program the microcontroller to drive the idle air valve.
>>
>>
>>
>> And once a prototype is built, we will need a vict-- I mean
>> volunteer-- to connect it to their rig for testing & fine tuning.
>> Preferably in the Portland, OR area.
>>
>>
>> --
>> Brett in Portland, OR
>> "Albert" '82 VanFox I4 Riviera
>> .
>>
> .
>