Acc Enrich

[Phil Lamovie]

Hi All,

Here's a simple method of calculating the required extra fuel for
sudden load
changes that will appeal to the programmers amongst us.

This supposes that you are running speed/density from a fuel table.

The TPS reading is taken from the A/D and placed on a stack.
This is done say 10 times every say 10 msec until a "history" of TPS
is
available.

As soon as a new reading is placed on the stack you do a 1st minus
last to give delta TPS. If the number is equal to the max. possible
delta you inject 100% of the Variable AccEnr ms  adding it to the Full
Load fuel ms for that RPM.

If its say 40 counts you add 40% of the AccEnr to the next injection.
Some ECU's calculate the proportion lost to some cylinders due to
their position in the cycle and add that to the next injection after
that. This is due to the fact that when ever you inject it is only
half the fuel that is supplied per
rev of the engine and some cylinders will only get 50% of the
enrichment.

This is also true if the result is negative you can subtract the
inverse and avoid the over rich "puff" that you get when the throttle
is closed suddenly

As you can see we are assuming that as the throttle is translating
rapidly the MAP sensor will be reading close to atms very "SOON" thus
we are using throttle translation as a predictor of ultimate load.

Now of course the algorithm for the decay of the AccEnr is something
that you didn't ask about but suffice to say you could make it a
variable based on the rate of change of RPM and the starting RPM and
the current load. There is quite a difference between "stabbing "the
throttle to change down a gear and flooring your Acc in gear.


 Phil
Injec Racing