[mkiv] Injector Duty Cycle Monitoring (ODBII)

[Dan]

i see... thanks for setting me straight.  i didn't realive it wasn't 
just a normas PWM signal.

dan


--- In mkiv at yahoogroups.com, "Grant Beaty" <gbeaty at u...> wrote:
Low impedance injectors aren't a square wave, it has a peak, then 
a "hold"
at a lower voltage, since it takes less volts to hold the injector 
open.
Thats why I suggested using a voltage regulator to "cap" the voltage 
off to
a certain value, which should transform it into a square wave 
(Assuming the
regulator works ideally).

All the multimeters I've used have a built in capacitor on the 
voltmeter
part. 50% duty cycle on my E Manage's injector driver (which IS a 
square
wave) shows up as 6v, 100% shows up as 12v, etc.

Grant

----- Original Message -----
From: "Dan" <jiggersplat at h...>
To: <mkiv at m...>
Sent: Thursday, April 24, 2003 2:00 PM
Subject: Fwd: Re: [mkiv] Injector Duty Cycle Monitoring (ODBII)


> the injectors use a pulse width modulated signal.  what this means 
is
> you get a square wave from 0 to whatever volts the injectors use.
> say the freqeuncy of the wave is 1Hz or one cycle per second.  a 50%
> duty cycle means that for that one cycle (one second) 50% of the 
time
> the voltage level is high, the other 50% it's low.  in general, this
> is how digital computers can control analog devices without an A/D
> converter.
>
> if you really wanted to use a multimeter, it is possible to design a
> circuit to convert a PWM signal into a voltage level.  you need to
> know the frequency of the PWM signal and you can select a properly
> sized capacitor and resistor.  there is however some latency to
> this.  it may take a few cycles before the voltage level accurately
> reflects the pwm signal.  a properly designed circouit should
> minimize the delay.
>
> dan
>
> --- In mkiv at yahoogroups.com, "Grant Beaty" <gbeaty at u...> wrote:
> OBD2 cannot display duty cycle on Toyotas.
>
> A multimeter won't wort too great, since its a peak-hold signal. The
> voltage
> spikes them drops down. Maybe if you used a 1v regulator to cut the
> voltage
> off and make it a square wave, the multimeter could read 0-1v for 0-
> 100%
> duty cycle. Thats just a guess though. It probably depends on your
> multimeter, I think most have a capacitor in the circuit somewhere
> anyways.
>
> Grant
>
> ----- Original Message -----
> From: "Chris Romano" <c_romano at y...>
> To: <mkiv at m...>
> Sent: Thursday, April 24, 2003 12:23 PM
> Subject: [mkiv] Injector Duty Cycle Monitoring (ODBII)
>
>
> > Is there a way to monitor the injector duty cycle?
> > Are there any connections where a multimeter can be
> > used to monitor voltage which may indicate injector
> > duty cycle percentages?
> > Just curious...I need to get some numbers on exactly
> > what is going on with my injectors and where they are
> > at.
> >
> > Thanks,
> > Chris
> >
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