Scott,

Thanks for the further elucidation on how things work in our beloved
steeds!!

John

On 11/16/2013 3:43 PM, Scott Daniel wrote:
> minor correction ...waterboxer injectors don't turn on 'every revolution' ..
> They are triggered continously in pulses...or in 'injector on time, in
> milliseconds of duration.'
>
>   - as one big 4 part injector too btw.  Called batch fire.
> Not sequential, not timed to engine or piston position.
> Somewhat crude.
>
> Dwell in distributors is the amount of angle in degrees that the points
> are closed..
> during which time a field is building up in the coil.  Smaller points
> gap equals larger dweel angle..and more charge time of the coil primary
> circuit.
> At the instant the points open, the field collapses, inducing the large
> secondary voltage that fires the spark plugs.
>
> I appreciated the PWM description for the Idle Valve .
> Very clear,
> thanks !
>
> Scott
>
>
> On 11/16/2013 1:31 PM, JRodgers wrote:
>> 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
>>>> .
>>>>
>>> .
>>>
>>
>