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injdata-voltage [2011/12/13 08:44]
twdorris created
injdata-voltage [2011/12/15 06:01]
twdorris
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 ====== Injector Data - Voltage ====== ====== Injector Data - Voltage ======
 Fuel flow rate through an injector is affected by a number of different things. ​ This page focuses on the effects of voltage across the injector. ​ Of all the things that might affect injector flow rate, particularly at idle and cruise pulse widths, voltage is one of the most influential. Fuel flow rate through an injector is affected by a number of different things. ​ This page focuses on the effects of voltage across the injector. ​ Of all the things that might affect injector flow rate, particularly at idle and cruise pulse widths, voltage is one of the most influential.
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 ===== Example ===== ===== Example =====
  
-The effect of varying voltage across an injector is easy for us to imagine because (1) the effect is pretty dramatic and (2) we can often demonstrate it while sitting in our car.  The image below shows one simple example of topping out the power windows, but because voltage is constantly being influenced by all sorts of things (alternator output which can be influenced by engine speed or fans coming on or off, etc.), the effect is actually pretty common in the real world.+The effect of varying voltage across an injector is easy for us to imagine because (1) the effect is pretty dramatic and (2) we can often demonstrate it ourselves ​while sitting in the car.  The image below shows one simple example of topping out the power windows, but because voltage is constantly being influenced by all sorts of things (alternator output which can be influenced by engine speed or fans coming on or off, etc.), the effect is actually pretty common in the real world.
  
 |{{http://​www.ecmtuning.com/​images/​forums/​injbatadj-1.gif?​300}}| |{{http://​www.ecmtuning.com/​images/​forums/​injbatadj-1.gif?​300}}|
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 So your ECU really has to adjust for this varying voltage in some way.  It can't just turn the injectors on for 3 ms and always expect to get the same amount of fuel.  As we'll see in the next section, a 3 ms pulse at 9v might produce no flow at all while the same 3 ms pulse at 14v might produce 200 cc/min of fuel or more! So your ECU really has to adjust for this varying voltage in some way.  It can't just turn the injectors on for 3 ms and always expect to get the same amount of fuel.  As we'll see in the next section, a 3 ms pulse at 9v might produce no flow at all while the same 3 ms pulse at 14v might produce 200 cc/min of fuel or more!
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 ===== Data ===== ===== Data =====
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 ^  //Click to enlarge// ​ ^ ^  //Click to enlarge// ​ ^
  
-Obviously, this effect is huge.  If the ECU calculates that it needs roughly 50 cc/min of fuel flow (for example), it would need to hold the injector open for 4 ms at 9 volt vs. about 2.3 ms at 12 volt.  That's a really big difference and clearly illustrates why it's critical for smooth operation to get your battery ​table set up correctly.+Obviously, this effect is huge.  If the ECU calculates that it needs roughly 50 cc/min of fuel flow (for example), it would need to hold the injector open for 4 ms at 9 volt vs. about 2.3 ms at 12 volt.  That's a really big difference and clearly illustrates why it's critical for smooth operation to get your voltage ​table set up correctly.
injdata-voltage.txt ยท Last modified: 2024/03/15 11:16 (external edit)