Well, I don't have a TBI-equipped vehicle...so sorry about that.
I mean...like say the TBI on a 1991 V6... take your pick on the model.
The whole "free run" thing doesn't make sense to me, as I would imagine
the injectors are either in a state of open or closed, not halfway as
the metering rods on a carb would be.
I mean, it obviously has a way of metering the fuel and maintaining the
A/F ratio via input from the O2 sensor. So I'd think it would do that
through varying the length of the pulses? No??
Big Al wrote:
Thottle body injection runs on a pulse width system, meaning they calculate
how long the fuel should spray per a given time, say 1 second. So if the
computer calculates that you're running at 10% of the maxiumum horsepower,
it will spray the injectors for 1/10th of a second, every second. Since the
fuel and air are traveling down the intake manifold they don't need to be
timed with the intake valves, the trip thru the manifold takes longer than
the opening and closing event.
That being said, most port injection systems fire in a left bank right bank
sequence. Most sequential injection systems only do so at lower rpms. After
a certain speed the injector takes longer to spray fuel than the valve is
open. But at higher speeds the momentum of the air traveling thru the
manifold keeps the fuel in suspension until the valve opens again.
Batch firing is normally a term used with port injection. Like on a 89 5.0
Mustang, the individual injectors are fired one at a time in the firing
order. SEFI, sequential electronic fuel injection. The 89 5.0 T-Bird fires 4
injectors at a time. That's called batch firing.
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