[Diy_efi] Re: Fixed frequency PWM batch mode FI

[Marcell Gal]

Hi, 

Ron Schroeder writes: 

> But, I would still prefer injecting on ignition events or crank sensor since
> the fueling calculations are much easier.

I agree with Ron.
If the firing is not synchonized, it can have 2
bad effects IMHO. 

 - too rare firing causing bad uneven mixture
(sometimes too rich, simetimes too lean) Why not use a carb :-) ? 

 - too frequent firing causes intensive injector wearout
(the injector is a magnetic valve - at least in my engine),
and you will have to calculate with the nonlinear
valve opening curves and do the appropriate measurements. 

Unfortunately you can avoid the first bad effect at quite
high free-running PWM frequencies (when the wearout will
be a problem). 

As many people pointed out on this list,
there is serious disadvantage of not synching the
injection to the engine rotation. 

On the other hand there is very very weak advantage
(gained simplicity) of free running injection timing
(since you have the sensors for injection ANYWAY). 

Of course you can do it, but do not count on quality
output. 

  Cell 


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