Just bought a 12-channel oscilloscope
02-20-2012, 05:09 PM
#2
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i recognize the bottom two traces.
the ones above that appear to be evenly spaced like batch ignition.
the top looks like more "crank" triggers.
edit: you did it in the future!
the ones above that appear to be evenly spaced like batch ignition.
the top looks like more "crank" triggers.
edit: you did it in the future!
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02-20-2012, 11:22 PM
#7
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Crikey!
We have a pair of Agilent mixed-signal scopes at work (4A, 16D) and those are about US$8,000 each. That's a hell of a nice piece of gear you have there.
And I'm wondering the same thing as Y8s. I've never scoped the INJ channels on an NB before, but I find it rather interesting that they are pulsing each injector twice per cycle at what I observe to be slightly above idle (looks like ~1200 RPM.)
Also, just out of curiosity, was that taken from an actual running engine? Those injector pulses look abnormally clean, and the duty cycle seems way too high for idle (6.85% based on 11 pixels/squirt x2 squirts across a 321 pixel cycle.)
We have a pair of Agilent mixed-signal scopes at work (4A, 16D) and those are about US$8,000 each. That's a hell of a nice piece of gear you have there.
And I'm wondering the same thing as Y8s. I've never scoped the INJ channels on an NB before, but I find it rather interesting that they are pulsing each injector twice per cycle at what I observe to be slightly above idle (looks like ~1200 RPM.)
Also, just out of curiosity, was that taken from an actual running engine? Those injector pulses look abnormally clean, and the duty cycle seems way too high for idle (6.85% based on 11 pixels/squirt x2 squirts across a 321 pixel cycle.)
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02-21-2012, 01:41 AM
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And I'm wondering the same thing as Y8s. I've never scoped the INJ channels on an NB before, but I find it rather interesting that they are pulsing each injector twice per cycle at what I observe to be slightly above idle (looks like ~1200 RPM.)
Also, just out of curiosity, was that taken from an actual running engine? Those injector pulses look abnormally clean, and the duty cycle seems way too high for idle (6.85% based on 11 pixels/squirt x2 squirts across a 321 pixel cycle.)
Also, just out of curiosity, was that taken from an actual running engine? Those injector pulses look abnormally clean, and the duty cycle seems way too high for idle (6.85% based on 11 pixels/squirt x2 squirts across a 321 pixel cycle.)
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02-21-2012, 08:00 AM
#12
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As said, that's what the 01+ ECU does. I've been thinking about why.
Let's suppose that Mazda "tacked on" the VVT algorithm to a non-VVT ECU in such a way that the injection algorithm was blind to intake valve timing, so they were unable to properly time injection events to actual intake valve opening. So perhaps they break up the fuel pulse into 2 half-pulses, 1 timed to where the earliest the valve could be open, and the second timed to the latest the valve could be open.
This is the only thing I can think of.
Let's suppose that Mazda "tacked on" the VVT algorithm to a non-VVT ECU in such a way that the injection algorithm was blind to intake valve timing, so they were unable to properly time injection events to actual intake valve opening. So perhaps they break up the fuel pulse into 2 half-pulses, 1 timed to where the earliest the valve could be open, and the second timed to the latest the valve could be open.
This is the only thing I can think of.
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02-21-2012, 12:00 PM
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I can't see how. Two separate squirts means twice the dead-time. Seems like it'd partially negate the purpose of going from batch injection to full sequential.
Reverant, I'd be very curious to see how the injector pulses change as you increase both RPM and MAF to get the ECU into a higher-load condition. Specifically, at what point do the two pulses merge into one?
Reverant, I'd be very curious to see how the injector pulses change as you increase both RPM and MAF to get the ECU into a higher-load condition. Specifically, at what point do the two pulses merge into one?
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02-21-2012, 12:05 PM
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I can't tell you why but it must be common for modern EFI systems to use multiple squirts per cycle. Here is the ECU timing diagram for an SRT-4 and you can clearly see that it squirts 3 times per cylinder every 720 degrees.
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