Changing injector pulse rate at idle?

[robert dingli]

John writes,
> ... 
> The disquieting aspect of the drive pulse was that while its duration 
> was constant, the period was varying between about a value of  
> about 40 milliseconds to one of about 45 milliseconds. Idle spped was 
> esentially constant.
> 
> Is this a commonly-used technique to achieve an EFFECTIVE pulse 
> width of less than 1 millisecond??  Is something more involved going on here??
> Anyone have any similar findings (or opinions)?? 
> 
> John
> 
John, while the engine speed may appear to be essentially constant, it isn't.
A 30 rpm variation is not uncommon between cylinder firings and one would
expect much more cycle by cycle.  The injection event is crank position
dependent and the variation you have described (40 - 45 mS) corresponds to
a 750 - 667 rpm variation, assuming one firing per cycle. 

I don't think anyone uses a variable period (speed independent) method for 
controlling injection quantity for port injection.
 
Robert


-- 
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             Robert Dingli           r.dingli at ee.mu.oz.au

Power and Control Systems                 Thermodynamics Research Lab
Electrical Engineering                    Mechanical Engineering
   (+613) 344 7966                           (+613) 344 6728
  University of Melbourne, Parkville, 3052, Victoria, AUSTRALIA
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