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Old 12-27-2009, 11:18 PM   #13 (permalink)
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Join Date: Jul 2009
Location: New York
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no nickname , it's just a car - '04 volkswagen golf tdi
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measuring injector opening

scan data does not measure
ACTUAL injector on time

you can use a high resolution scope .
it is easiest to measure injector open with injector current waveform and it is easiest to measure injector close with injector signal voltage

the open time is about 70% of signal time but varies with different systems

above the Blue trace is Injector current , the red trace is Injector signal voltage - BUT
this waveform was captured using an injector tester pulsing 4ms signals , it is NOT the same as what you will see on a running car / system
you can see the "gull" in the current waveform which is caused when the magnetic field changes because the pintle has moved opening or closing the injector's opening

an operating system looks like this
pintle movement is clearer and easier to see , this what an actual system waveforms will look like , black is voltage green is current

Originally Posted by smonson View Post

I've built a similar gauge for my '99 Nissan Pulsar (which I think is Almera or Altima or something like that in the USA) after being impressed by the MPGuino when it got mentioned on hackaday. My hardware is similar but totally different software.

My question applies to the OpenGauge/MPGuino as well as my thing. Has anyone actually measured the opening and closing delay of a fuel injector? How do we know it's ~500uS? If the opening time is because of the physical movement of the valve, wouldn't there also be a similar closing delay?

Thanks. -Simon

Last edited by mwebb; 12-28-2009 at 12:05 AM.. Reason: added another image
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