Throttle enrichment - why, how much?

[xxalexx at ix.netcom.com]

> From:          "Thor Johnson" <thormj at earthlink.net>
> To:            <diy_efi at efi332.eng.ohio-state.edu>
> Subject:       RE: Throttle enrichment - why, how much?
> Date:          Thu, 16 Jul 1998 08:55:34 -0400
> Importance:    Normal
> Reply-to:      diy_efi at efi332.eng.ohio-state.edu

> > 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?
> 
There are non contact load sensors available that sense driveshaft 
torque.  Also could use a G-meter.
alex