[Diy_efi] Measuring Pulse Width/Duty Cycle of an Injector?

[Andrew Hopton]

P&H is shorthand for Peak & Hold.  This is a type of injector drive/injector
where the full voltage is applied to open the injector initially, but the
current is then rapidly switched for the remainder of the injector 'on'
period.  This keeps the injector open, but limits the current.  This allows
injectors with a lower impedance to be used, which (and this is where I
start presuming) means they can open more quickly/reliably.

Because a normal duty cycle measurement is comparing 'on' time to total
cycle time, it is confused by the P&H waveform.

The device I was talking about can 'read' a P&H waveform and output a normal
pulse waveform with the same on/off periods as the injector.

Now if we could only get it to work in reverse ....

-----Original Message-----
From: diy_efi-bounces at diy-efi.org [mailto:diy_efi-bounces at diy-efi.org] On
Behalf Of Mike
Sent: Monday, 23 May 2005 3:59 AM
To: diy_efi at diy-efi.org
Subject: RE: [Diy_efi] Measuring Pulse Width/Duty Cycle of an Injector?

At 08:32 PM 22/05/05, you wrote:
>I have seen a kit that converts a P&H waveform into an equivalent simple
>pulse waveform, expressly for the purpose of duty cycle measurement.  It
>uses a dual op-amp IC and a handful of other small components.  I have a
>magazine article that 

Sorry I'm missing something here - whats P & H ?

Did u mean Pulse Width ?

Regards from


Mike Massen
Perth, Western Australia
VL Commodore Fuse Rail that wont warp or melt !
Twin Tyre rims and tyres for sedans
http://niche.iinet.net.au


>describes it.  Let me know if you need more info, or contact me off-list if
>you'd like the name of the kit retailer.
>
>Cheers
>
>-----Original Message-----
>From: diy_efi-bounces at diy-efi.org [mailto:diy_efi-bounces at diy-efi.org] On
>Behalf Of Marcello A. Belloli
>Sent: Sunday, 22 May 2005 1:01 PM
>To: diy_efi at diy-efi.org
>Subject: [Diy_efi] Measuring Pulse Width/Duty Cycle of an Injector?
>
>Hello Everyone,
>     I'm still working on a datalogger project.  Been doing a lot of the
>software while I've been on vacation in Thailand. I'm still on
>vacation, but can't keep my mind off of this project.  I'm using a
>PIC18F452 as the Micro behind my datalogger.  I've got just about
>everything working.  The one place I'm having problem is the
>understanding of how to read pulse width of a fuel injector.
>     Is there a way of looking at all types of injectors, that will allow
>for an accurate account of timing?  I've been looking at two type of
>injector firing.  Low resistance injectors, which use a driver that
>duty cycles the injectors after the main firing to keep the current
>within limits.  And Higher resistance ones where the resistance alone
>keeps the current down.  Now how do you look at firing time of an
>injector when the driver starts to duty cycle it after 1.2ms?
>     I guess I have one more question too - What is the best way to
>connect to a circuit like an injector driver output?  I figure I only
>really need timing information.  I want to keep the voltage between
>0-5 volts and apply as little load to the circuit as possible.
>     After looking at this I can understand why my multimeter that has a
>PulseWidth setting has trouble sometimes.
>     Any ideas would be great.    Thanks,  Marcello
>_______________________________________________
>Diy_efi mailing list
>Diy_efi at diy-efi.org
>http://lists.diy-efi.org/mailman/listinfo/diy_efi
>
>-- 
>No virus found in this incoming message.
>Checked by AVG Anti-Virus.
>Version: 7.0.322 / Virus Database: 266.11.14 - Release Date: 20/05/2005
> 
>
>-- 
>No virus found in this outgoing message.
>Checked by AVG Anti-Virus.
>Version: 7.0.322 / Virus Database: 266.11.14 - Release Date: 20/05/2005
> 
>
>_______________________________________________
>Diy_efi mailing list
>Diy_efi at diy-efi.org
>http://lists.diy-efi.org/mailman/listinfo/diy_efi

Regards from


Mike Massen
Perth, Western Australia
VL Commodore Fuse Rail that wont warp or melt !
http://niche.iinet.net.au

_______________________________________________
Diy_efi mailing list
Diy_efi at diy-efi.org
http://lists.diy-efi.org/mailman/listinfo/diy_efi

-- 
No virus found in this incoming message.
Checked by AVG Anti-Virus.
Version: 7.0.322 / Virus Database: 266.11.15 - Release Date: 22/05/2005
 

-- 
No virus found in this outgoing message.
Checked by AVG Anti-Virus.
Version: 7.0.322 / Virus Database: 266.11.15 - Release Date: 22/05/2005