X-post from B5 S4 forum re: injector duty cycle.....
07-24-2005, 07:21 PM
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X-post from B5 S4 forum re: injector duty cycle.....
TIA for any insight you may have.<ul><li><a href="https://forums.audiworld.com/s4/msgs/2063175.phtml">Click!</a></li></ul>
07-25-2005, 08:23 AM
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At 6000 RPMs (for example), it takes 20ms for a full cycle (2 strokes).
Therefore, 20ms is 100% duty cycle at that RPM. If the specified pulse is longer than 20ms, then it just means that the injector is spraying through the full cycle (100%). You can't fit 35ms of spraying time into a 20ms cycle.
-Dave Pramanik
-Dave Pramanik
07-25-2005, 11:28 AM
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What was different in obtaining the two graphs? I don't think an injector swap will change WOT d/c
unless it detected overlean conditions and the whole system is backed off.
Having said that, how's your O2? was it lean before the swap?
Having said that, how's your O2? was it lean before the swap?
07-25-2005, 01:40 PM
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I never said that it was spraying 35ms, just saying that the ecu can read up to 35ms at any rpm.
Just found it funny that he said his injector duty cycle was over 130-140%, which I dont think can happen. If the injector was at 110% duty cycle at 6k rpms and the air flow was still increasing, the car would run lean in the higher rpms.
I guess a chart is needed to show how much ms at set rpms = 100% duty cycle.
I guess a chart is needed to show how much ms at set rpms = 100% duty cycle.
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07-26-2005, 05:55 AM
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Its pretty simple...
From the RPM, you can calculate the time required for each revolution in milliseconds. Then double it for the time for the full cycle - 2 revolutions/4 strokes (intake, compression, ignition, exhaust).
Thats the maximum amount of time that the injectors can be open. Specifying a longer pulse width is pointless because you are into the next cycle (but tuners still do it).
<img src="http://www.pramanik.net/AW/duty.GIF">
-Dave Pramanik
Thats the maximum amount of time that the injectors can be open. Specifying a longer pulse width is pointless because you are into the next cycle (but tuners still do it).
<img src="http://www.pramanik.net/AW/duty.GIF">
-Dave Pramanik
07-26-2005, 06:26 AM
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Thanks.
But would the car run lean if the duty cycle is over 100%? The reason I ask is because I had no problems holding 35ms readings even on my K03 and K04 setup at high rpms and the car never ran lean.