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Sounds like you have the problem identified,
John. It certainly could be the problem. The Saturation type
injectors are generally around 12-16 ohms resistance and the peak and hold
around 2-5 ohms. So the EC2 would provide a nominal 14/14 = 1 amps to the
staturation type, but with out the 5 ohm resistor and using peak and hold with
lower resistance the current 14/3.5 = 4 amps taking the middle resistance value
of the range of each type injector. With the resistor they should see
approx 14/8.5 = 1.5 - 2 amps.
The peak and hold tend to open faster than the
saturation type so you do not need as much injector-on time to get the same fuel
flow. In fact if the Peak and Hold are driven with an injector pulse
duration calculated for a statuation type injector then you would get more fuel
flow for the same pulse duration.
According to MSD the Satuation types take approx 2
milliseconds to open whereas the Peak and hold only take 1.5
milliseconds.
Back of an envelope calcuations shows that With an
pulse duration of around 4 milliseonds typical, then the
2 -1.5 = 0.5 milliseconds difference would equate to a 0.5/4 = 12.5% more
fuel flow approximately. But since your peak and hold were being
overdrive with current (without the 5 ohm resistor) the difference may
have been even more. Those suckers probably jumped from closed to full
open in 1 msec or less {:>_ with that 4 amp kick.
That is one thing about these Mazda
Rx-7 injectors, its really easy to get caught if you don't actually
measure the resistance. I have satuation type injectors with the same
color electrical connector AND same part number stamped on the electrical
connector but one set are peak and hold and the other 4 are saturation
type. Error in manufacturing?? don't know. Also, the 560
cc saturation injectors came with a purple connector and an unpainted
(silver) body. Guess, what, some folks have cleaned off the scratched up
black paint off the 460 cc injectors and with a faded red connector - it
can (and has been) mistaken for the 560 cc injector. So you gotta be
careful.
Ed
Ed Anderson
RV-6A N494BW Rotary Powered
Matthews, NC
----- Original Message -----
Sent: Friday, July 02, 2004 9:24 PM
Subject: [FlyRotary] Re: EC2
programming
I
think I found the problem.... or at least Tracy did. He realized that my
symptoms would be a lot like what you'd get if you used peak & hold
resistors without the 5 ohm resistors.
About 2 years ago I got 2 purple 550cc injectors from
Bruce. They were Saturation type, so I didn't need resistors.
A
year later I got two more from the local Mazda shop for the secondaries. They
were purple, so I ASSumed they were the same. I tested them tonight and
found that they're the peak & hold type. Without resistors they get
too much current and they don't open and close as the EC2 expects. Result -
uncontrollable mixture problems.
OK,
so how do I get 2 * 5 ohm 25 watt resistors on a holiday
Saturday?
John
(mix & match) Slade
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