[Diy_efi] Hi and JECS injector question

[Bevan Weiss]

The straight answer is yes, with the ballast resistor the current through
each injector will rise slower than it would have otherwise, and hence will
open slower (and also close slower).
However if you're running peak-and-hold injectors (low impedance) with a
saturated injector (high impedance) driver then the ballast resistor is your
only option to avoid destroying either the injectors or the drivers (maybe
even both).

Saturated injectors open slower than peak-and-hold injectors anyway, so
you're probably in the same ballpark as using straight saturated injectors
in terms of response time.  The best option is of course peak-and-hold
injectors with a peak-and-hold driver, however this isn't really an option
for you.

I'm not sure entirely what it is you're trying to do.  I assume that it's to
replace the ECU with something other than stock, but still keep using the
old (peak-hold) injectors.  Or perhaps you still want to use the original
ECU but with some newer (peak-hold) injectors.  In either case the ballast
resistor (of around 11Ohms/12Ohms) would be needed for each injector.  This
would just be placed between the driver and the injector.  The other
injector terminal would then be connected to 12V.

If your ECU is sequential, then each injector should have one terminal
commoned to the 12V supply of the car, and the other terminal should connect
to the respective ballast resistor for that injector, the remaining terminal
of the ballast resistor then connects to the respective driver for that
particular injector (based on cylinder position for the injector).

Don't connect together all the sequential outputs from the PC3 unit.  They
should all be open drain type drivers, but you never know what kind of
design they use and it may be as wacky as a push-pull (totem pole) type
driver, in which case connecting them all together would destroy the
drivers.
 

-----Original Message-----
From: diy_efi-bounces at diy-efi.org [mailto:diy_efi-bounces at diy-efi.org] On
Behalf Of Lorcan Parnell
Sent: Friday, 30 April 2004 7:51 a.m.
To: A list for Do-It-Yourself EFI
Subject: Re: [Diy_efi] Hi and JECS injector question

My apologies for the lack of detail. Now that I have managed to confuse one
or two (including me!) perhaps the following will simplify things.

The Dynojet Powercommander 3 I want to use is intended for use on bikes with
high impedance (13-16ohm) sequential injectors. It has four inputs (one per
cyl) and 4 output wires.

The bike I want to fit it to has four low impedance (2.6ohm) batch-fired
injectors. The ECU has a single output trigger wire which goes to all 4
injectors (which I can tie to all 4 inputs on the PC3), and all 4 injectors
have a tied 12v feed direct to the battery.

 If I fit a resistor (10ohm?) to each output of the PC3 will each injector
get less voltage than stock and open slower?

I don't want to get it wrong and fry the injectors, the PC3 or the ECU, so
thanks for the help!

Lorcan


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