[Diy_efi] problem with ecu and injector duty

[Carter Shore]

Yes, that's exactly the point of my post; 

Duty cycle is ratio of On-time to Off-time.
If the injectors are not triggered synchronously with
the crankshaft, and all you know is the On-time (17
mS) then either the pulse *frequency* or Off-Time must
be known in order to calculate the duty cycle. 

Some batch-fire schemes are asynchronous with the
crankshaft, but it doesn't appear to me that this is
one of them, after examining the site.

Carter Shore

--- Daniel Nicoson <A6intruder at myo-p.com> wrote:

> At 550 RPM on a four cycle engine he has just
> slightly over 20ms available
> (6000 RPM a PW=20ms is 100% duty cycle).
> 
> Dan Nicoson
> 
> -----Original Message-----
> From: diy_efi-bounces at diy-efi.org
> [mailto:diy_efi-bounces at diy-efi.org]On
> Behalf Of Carter Shore
> Sent: Tuesday, November 14, 2006 11:05 AM
> To: diy_efi at diy-efi.org
> Subject: RE: [Diy_efi] problem with ecu and injector
> duty
> 
> I have not looked at the link yet, but are you sure
> that the ECU is sequential, rather than batch?
> The injector pulsewidth/duty cycle only makes sense
> if
> you know what the underlying pulse frequency is, ie
> what's the dead time?
> 
> --- Mark Riley <turbotuneusltd at triad.rr.com> wrote:
> 
> > I would hook up a fuel pressure guage and see that
> > the fuel pressure does
> > indeed rise 1 for 1 with the boost level. I would
> > suspect that perhaps the
> > Pump is not keeping up at the upper pressure
> levels.
> > If the guage shows any
> > fluctuation at over 10 psi boost or does not make
> > the correct pressure rise
> > all the way to max boost, the pump is not capable.
> >
> > Mark Riley
> >
> > -----Original Message-----
> > From: diy_efi-bounces at diy-efi.org
> > [mailto:diy_efi-bounces at diy-efi.org] On
> > Behalf Of Damian Long
> > Sent: Monday, November 13, 2006 8:44 PM
> > To: diy_efi at diy-efi.org
> > Subject: [Diy_efi] problem with ecu and injector
> > duty
> >
> > Hi,
> >
> >   I have a rather strange ecu. Most likely not
> many
> > people have used it
> > before. It is a Walbro Bike400. You can get some
> > information from here
> > www.walbro-tdd.com
> >
> >   Since installing and running this ecu I've tuned
> > the vehicle and found
> > I've needed some very stupid injector opening
> times.
> > At 2bar boost and
> > 5500rpm I need 17mS opening time!
> >   Vehicle is 1600cc 4cyl turbo.
> >   The injectors are Nippon denso 16ohm 550cc/min
> > @40psi. part no
> > 1955000-2020. The fuel pump is a Bosch motorsport
> > unit. 150lph @ 5bar. The
> > pump, regulator and rail pressure all check out ok
> > so I've discovered that
> > its an issue with the ecu or wiring to the
> > injectors. Basically the ecu need
> > to send a 17mS opening time in order to get the
> > injector to open long enough
> > to supply fuel. The injectors are well sized for
> the
> > application.
> >   Does anyone have any ideas where I should be
> > looking for a solution to the
> > problem? So far I have the following ideas but now
> > sure if any are relevant.
> >
> >   1. ecu is designed for peak and hold injectors
> and
> > this is why
> >   2. wiring to injectors wrong way round. ie. coil
> > polarity wrong
> >   3. injector voltage offset table set up wrong in
> > ecu
> >   4. ecu is lying or is just plain cr p and I
> should
> > burn it
> >
> >   I flow tested injectors. They are ok. Any ideas?
> >
> >   thanks
> >
> >
> >
> >  Send instant messages to your online friends
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> 
> 
> 
> 
>
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