Throttle enrichment - why, how much?

[Thor Johnson]

> These are only my experiences but here goes.
> The RPm part of the map is to allow for the changing Volumetric
> efficency of the motor through the rev range. ie coming on cam and off
> cam to simplify it a lot. My experience is with mild street type cams
> the MAP input on its own is enough to make the car quite drivable. You
> do still need an accelerator pump type of system though. What i use is
> percentage enrichment that depends on delta throttle in a fixed time and
> then decays at set rate. You need to make the percentage and the decay
> rate setable.

It was *drivable*, but it had some nasty gotchas.  I had a settable, fixed
boost
and a settable, fixed decay...  One of my main problems has been attempting to
tune
this guy.  How different is static (ie, engine in neutral) vs dynamic (drivin')
for
this?


> This function is needed to allow for the engines requirement of a static
> richer mixture during transient acceleration and also to allow for the
> lag between the air flow and the fuel flow due to their differing
> densities in the manifold. Ie with something like throttle body
> injection with injectors a long way from the valve you will need more
> percent and slower decay. With race type inlet runners one per cylinder
> and injectors close to the valve you almost don't need any boost.

Hmm. a compromise.  This is a FSAE class car, so it has a single tuned inlet
(splits into 4),
but the injectors are mounted about 2 inches away from the intake.

> With regard to the sensors it depends which ones you are trying to read.
> I read load every revolution, calc RPM every rev and everything else
> about 10 times a second.

"Load"?  what sensor does that?

-Thor Johnson
thormj at iname.com