No subject

is  
pretty bad.  Bottom line is that MAF costs more and doesn't work as  
well  
at WOT...  compared to well tuned speed-density systems.  The  
question  
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  
equation  
> of (1.2.2) that would add a pre-set quantity of fuel as a function  
of  
> throttle change. Additionally, it would have an adjustable "decay  
parameter"  
> that would be similar to the hole diameter of the "shooter". In  
the future,  
> it may be beneficial to include MAP and coolant temperature into  
this  
> term. For now, I will just represent it as a yet to be defined  
additive  
> function of AE. (need more info here --- need to define the  
controlling  
> algorithm)  
  
It's actually pretty important to have the 'shooter size' and 'decay  
rate'  
controlled by engine temperature.  
I've seen systems that have two accel pumps: one for delta MAP and  
the other  
for delta throttle.  
  
Ideally, you would model the fuel thickness in the intake manifold  
between  
the injector and valve, which would require air temp, manifold temp,  
manifold  
vacuum/pressure, and probably an estimation of the willingness of  
the air  
to accept the gasoline as a vapour. This is something for someone  
who has  
done research on this area... if you can model it, you don't have to  
spend  
as much time tuning...  
  
> 1.3.2 --- Deceleration Enleanment (DE)  
>   
> I don't believe this term is necessary in the first prototype of  
our  
> controller. Ultimately this term will lean the engine during  
deceleration  
> much as the acceleration enrichment term adds fuel during  
acceleration. It  
> should have the same inputs as the acceleration term.  
  
Exactly. Just acceleration enrichment turned around. It only adds  
about  
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  
cough  
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  
error from  
> the oxygen sensor. The conditions for when this term should be  
included are  
> yet to be defined. Conditions to consider are cold O2 sensor, cold  
engine,  
> acceleration, deceleration, power enrichment. (others?) (need more  
info here,  
> need to define the controlling algorithm)  
  
Actually, I've seen it done as a combined additive and  
multiplicative term.  
The short-term feedback (oscillator) is additive, the long term  
(block-learn)  
is multiplicative. I guess this simplifies control calculations...  
  
Most FI software I've seen has a lot of compensation for the  
temperature  
effects on the O2 sensor. A lot of engine control software attempts  
to  
predict the temperature of the exhaust and the exhaust system  
components  
to compensate for this. I thought it was wierd, too...  
  
-Dale