Bench racing ecms Even if ya hate 101 please read

[richard vandervoort]

>On Thu, 18 Jun 1998 11:39:17 -0700, "richard vandervoort"
><fastski at mailexcite.com> wrote:
>
>>>Speaking as a "magazine expert" here...  Other people have posted that
>>>battery voltage makes a difference to the fuel injector as far as how
>>>fast it opens, etc.  So I believe the ECM does have a battery voltage
>>>correction for injector on time.
>
>>From my experience working with ABS valves (solenoid) it would seem 
>foolish for the injector (solenoid) power to not be regulated.  If it is
>regulated there would not be any need to correct for voltage changes in
>software.  The time for the plunger to move should be relatively fast
>compared to the total on time of the solenoid.  Solenoid valves are
>usually rated by an on time, flow versus pressure curve, mimimum turn on
>voltage(or pressure), and duty cycle.  Flow through the valve is
>regulated by power on time.  Using high frequency PWM of voltage the
>flow rate through the valve can be partially controlled.  This however
>is dependant on plunger and valve seat shapes and may not work very well
>since typical injectors are designed for on off operation.
>
>[richard, no word wrap?]
>
>Weeeell, then I guess you're just gonna have to color the auto makers
>"foolish", then. On the other hand, to folks where every penny counts
>(bean counters abound there, ya know), the cost of regulating a fairly
>hefty amount of power, relative to the cost of reading the +BAT voltage
>and making a tweak with a few linesOcode, might seem like a pretty
>"unfoolish" tradeoff to them guys. Heh.
>
>Gar
>
>

Let me state something in simpler terms. When using solenoids valves for ABS with minimum on time of 3 milsec the voltage does not make a significant difference to flow until the valve does not open.  I do not know how far the fuel injector manufactures push their solenoid valves into the nether world of partial opening, or even what is a typical on time for an injector.  The relationship between plunger movement time and voltage is at least a second order relationship plus temperature (fluid viscosity) and pressure (fuel supply to intake plenum differential) dependant so the code may be a lot more than a few lines.  Since we know these other variables are not measured and estimating them would be quite innacurate, I would measure injector voltage in a running car while decreasing supply voltage (battery)if you really want to find the answer.


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