Thu May 30 05:48:45 GMT 2013
pretty bad. Bottom line is that MAF costs more and doesn't work as
at WOT... compared to well tuned speed-density systems. The
to ask is does the esier tuning outweigh its other disadvantages?
Jonathan R. Lusky -- lusky at knuth.mtsu.edu
"Turbos are nice but I'd rather be blown!"
68 Camaro Convertible - 350 / TH350
80 Toyota Celica - 20R / 5spd
> In the prototype controller, AE should simulate the accelerator
pump of a
> traditional carburetor. That would make it an additive term to the
> of (1.2.2) that would add a pre-set quantity of fuel as a function
> throttle change. Additionally, it would have an adjustable "decay
> that would be similar to the hole diameter of the "shooter". In
> it may be beneficial to include MAP and coolant temperature into
> term. For now, I will just represent it as a yet to be defined
> function of AE. (need more info here --- need to define the
It's actually pretty important to have the 'shooter size' and 'decay
controlled by engine temperature.
I've seen systems that have two accel pumps: one for delta MAP and
for delta throttle.
Ideally, you would model the fuel thickness in the intake manifold
the injector and valve, which would require air temp, manifold temp,
vacuum/pressure, and probably an estimation of the willingness of
to accept the gasoline as a vapour. This is something for someone
done research on this area... if you can model it, you don't have to
as much time tuning...
> 1.3.2 --- Deceleration Enleanment (DE)
> I don't believe this term is necessary in the first prototype of
> controller. Ultimately this term will lean the engine during
> much as the acceleration enrichment term adds fuel during
> should have the same inputs as the acceleration term.
Exactly. Just acceleration enrichment turned around. It only adds
fifty or so lines in my code (assembler). Makes a big difference when
you're coming out of a corner and you don't have to let the engine
out the raw gas it sucked in on the overrun.
> 1.3.3 --- Close-Loop Feedback (CLF)
> This should be a multiplicative term representing the integrated
> the oxygen sensor. The conditions for when this term should be
> yet to be defined. Conditions to consider are cold O2 sensor, cold
> acceleration, deceleration, power enrichment. (others?) (need more
> need to define the controlling algorithm)
Actually, I've seen it done as a combined additive and
The short-term feedback (oscillator) is additive, the long term
is multiplicative. I guess this simplifies control calculations...
Most FI software I've seen has a lot of compensation for the
effects on the O2 sensor. A lot of engine control software attempts
predict the temperature of the exhaust and the exhaust system
to compensate for this. I thought it was wierd, too...
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