injector staging

[Axel Rietschin]

From: <bill.shurvinton at nokia.com>
>
> Hi,
>
> Sorry to interupt everything with an EFI question, but I wondered what
> the rule of thumb was when doing staged injection in terms of when it
> was better to run one injector and when to switch to 2. looking at
> standard injector ramping profiles it would suggest that, once your
> total squirt is around 1ms then you have sufficient accuracy to meter
> fuel (for Bruce: metre is the unit of length=39.27inches), but below
> 0.5ms it starts to get difficult due to injector opening and closing
> times becoming significant.
>
> Any pointers would be appreciated.

If you use twin injectors, mounted side by side close to the valves, wait
until you need ~4ms on the first bank, then split (i.e. 2x~2ms). When you
fall below 2x1.8ms, unsplit. Adjust if you bank split is not 50/50 (i.e. if
you use different injectors) to make sure you don't have a very short pulse
on one of the banks. When splitting you may need a little more fuel for a
short time, likewise you may need to remove a bit when unsplitting, due to
manifold effects. If you use a hi/lo setup, where the second bank is located
relatively far from the valve, you may want to wait a little more before
splitting. The idea is to use only one bank when starting, idleing and
driving at very light load.

--Axel


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