injector drivers

[John Dammeyer]

-----Original Message-----
From: Jemison Richard <JemisonR at tce.com>
To: 'diy_efi at efi332.eng.ohio-state.edu'
<diy_efi at efi332.eng.ohio-state.edu>
Date: Sunday, March 07, 1999 3:06 PM
Subject: RE: injector drivers


>John,
>
>How about some details of your design - maybe some parameters, example
maps?
>Also, the ignition system.  Are you able to advance completely
>electronically or do you still depend on a mechanical advance system -
to
>any extent?   Catch me offline if you'd rather.   Sounds great!
>

Yes,  I advance completely electronically.  I use grey code for
determining which of the four quadrants I am in on the camshaft.  The
unit has a CAN bus so I spit out the engine parameters to a PC via CAN
and then display on a PC the entire instrument panel using Delphi and
ActiveX.  I have a circular gauge that has 720 degrees and a set of
coloured anular rings representing Intake valve open, Exhaust valve
open,  the needle shows advance and a third red ring shows the injector
pulse width.  Under low pulse widths it sits nicely under the blue
intake valve portion starting inection about 5 degrees after the intake
starts to open.  As the engine speeds up the red ring creeps in the same
direction until about 5 degrees before the intake valve closes. After
that the open time shifts earlier and earlier into the engine cycle.  At
RPM's under 4000 there is no intake/exhaust overlap.  At 4000 RPM the
indication that the VTEC solonoid has been activated arrives and so the
two anular rings that show valve timing change to show that now there is
exhaust/intake overlap.

I run stock injectors at 80% duty cycle.  The ignition is High Energy
Capacitive Discharge and produces a decent spark even at 8V battery
voltage.

It's really quite fascinating to watch.  As the engine speeds up the
valve and ignition timing changes graphically on the PC screen.  I have
a linear gauge that shows the O2 sensor and it tracks mixture nicely.

Overall,  thanks to information from Bruce Bowling,  Al Grippo,  a
series of articles in Circuit Cellar Ink by Ed Lansinger along with all
sorts miscellaneous application notes from Siemens and Philips Semi.
the system is coming along nicely.   Hopefully,  we'll be testing
injection on the dyno this week.

So far,  with an Alison mechanical fuel injection throttle body the
ignition has allowed the engine to produce 130HP at maxium RPM.   And we
know that the Alison doesn't provide an even mixture to the cylinders.

Cheers,

John



>rick
>jemisonr at tce.com
>
>> -----Original Message-----
>> From: John Dammeyer [SMTP:johnd at autoartisans.com]
>> Sent: Sunday, March 07, 1999 3:59 PM
>> To: diy_efi at efi332.eng.ohio-state.edu
>> Subject: Re: injector drivers
>>
>> Hi All,
>>
>> I'm building a ignition/injection system for a Honda 1595 CC engine.
So
>> far the CD ignition works great as do all the appropriate sensors
like
>> the MAP/Air Temperature etc.  I'm wondering how to go about handling
the
>> Throttle Position Sensor.
>>
>> ie:  While the engine is in a steady state condition the combination
of
>> MAP and Barometric Pressure sensors along with RPM determine the
initial
>> injector pulse width.  The O2 sensor closes the loop.  Now if the
>> throttle is opened suddenly I know I need to increase the pulse
width.
>>
>> I can:
>>
>> 1)  just use a timer to increase the mixture to 10:1 for a
preprogrammed
>> time.  This simulates the accelerator pump on a carburated engine.
>>
>> 2)  Increase the mixture to 10:1 until the ratio between MAP and
>> Barometer reach some set point.
>>
>> 3) Do both.
>>
>> What I don't want happening is a too rich mixture once the throttle
is
>> wide open and the engine is loaded at some RPM that no longer
increases.
>>
>> Would I be best to use the rate of change of the RPM as an indicator
to
>> back off on the Pulse Width?
>>
>> What do the commercial injection systems do?
>>
>> Comments?
>>
>> Thanks,
>>
>> John
>