In article ,
Aaron Coolidge wrote:

I have yet to see a fuel-injected car that fires its injectors at exactly
the right time as the intake valve opens. The injector is a little solenoid,
and has ~5 mS response time opening - longer when closing. A 3600 RPM car
engine is running at 60 Hz, ie, one revolution per 16.67 mS.

On my analog fuel injection car (1977), all the injectors run in parallel.
Pulse width is varied according to RPM. The airflow meter biases the pulse
width a tiny bit. The injectors create a little cloud of finely atomized
gasoline which gets sucked into the cylinder as the intake valve opens.
Interestingly enough, although it's port FI, there is a single injector
in the intake manifold just aft of the throttle body. It turns on at full
throttle to further enrichen the mix, and also gives a shot of fuel when
starting the engine presumably for priming (there is no choke, of course).
It's the height of 70's technology which the Japanese licensed from the
Germans (Hitachi copy of L-Jetronic).


Bosch Motronic cars fire the inyectors individually so they are open while
the intake valve is. You are correct that at a mid to upper range
injectors are open more that what the intake valve is open. It just poodles
behind it.


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Eduardo K. |
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