Asynchronous injection (and PLD)

[rr]

Generally yes. On a tbi ecm gm set it up to use async pulses for an
accel
enrichment. They sputter asynchronously between the normal sync pulses.

The other time async is used, is when the sync pulses get so short that
they can not meter fuel accurately enough. The ecm will switch to async
pulses until the required sync pulses are large enough again.

BobR.


Jeroen Proveniers wrote:

> Hello,
>
> is asynchronous firing of the injectors necessary, except when starting?
>
> I'm currently investigating the use of a PLD (Altera MAX7000S) to implement
> all the timing logic for injection and ignition, so when async firing is an
> absolute requirement I've to account for it.
>
> Short description of the PLD:
> The PLD is aimed at sequential injection. Synchronisation to the engine is
> by 2 sensors at the camshaft. Injection start can be controlled by the main
> controller. In fact, sensor one gives 60 pulses per revolution that
> decrements a counter, while the other sensor resets the counter to a
> predefined value (reset value). When the counter is at zero it's reloaded
> with the reload value at the next pulse. At terminal count an other counter
> is kicked that selects the injector, and injection is then started by
> kicking a oneshot timer (16 bits, clocked at 1MHz).
>
> So injection starttime can be controlled by changing the reset value. The
> reload value is fixed as it defines the number of cylinders.
> I'm also thinking about stopping injection when intake valves close, instead
> of starting injection when the valve opens.
>
> JJ
>

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