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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: going from low to high impedance injectors??
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Sun, 14 December 2003 14:40
 
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well, to start, measure the resistance of the resistor pack 
the 4KE resistor pack i have has 2 injector outs, and each is about 3.8ohms. each injector is 2.4ohms. i can't remember how to work out current flow thru each branch of a resistor network, so i'll leave that to you 
a 12ohm injector with 12V will have around 1amp running thru it.
a low impedance injector will have maybe 2 or 3amps to crank it open, and then a hold current of maybe 25-50% of this.
on megasquirted cars, ppl are successfully using resistor packs with low impedance injectors, and using saturation method.
10 ohms is a pretty big difference to the ECU...as you are considering how many amps the ECU is grounding.
since power is supplied to the injectors, and the ECU just grounds them, you can work out roughly the max current that flows thru the ECU (assuming it just shorts the injectors) by working out total resistance of injector and resistor pack, depending on how many injectors there are for each circuit of the resistor pack.
if the high imp inj's have more resistance than the sum of the low ones with the res's, then the total ECU current will probably be lower, and might be ok..
you also need to consider the 'flyback current' generated when the injector closes, as high imp flyback is bigger than low imp flyback (maybe due to larger inductance???)
there is a possibility that the flyback spike can take out the injector drivers....
anyhoo, a few things to think about...
oh and have a look at this page, they discuss what size resistors to use with low imp injectors, which you may be abl eto use to back calculate stuff
http://members.shaw.ca/megasquirt/manual/minj.htm
Cya, Stewart
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| | Subject | Poster | Date |
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going from low to high impedance injectors??
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ed_ma61 | Sun, 14 December 2003 12:49 |
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Re: going from low to high impedance injectors??
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oldcorollas | Sun, 14 December 2003 14:12 |
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Re: going from low to high impedance injectors??
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ed_ma61 | Sun, 14 December 2003 14:17 |
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Re: going from low to high impedance injectors??
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oldcorollas | Sun, 14 December 2003 14:40 |
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Re: going from low to high impedance injectors??
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oldcorollas | Sun, 14 December 2003 14:42 |
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Re: going from low to high impedance injectors??
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Simon-AE86 | Sun, 14 December 2003 14:37 |
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Re: going from low to high impedance injectors??
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Simon-AE86 | Sun, 14 December 2003 14:51 |
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Re: going from low to high impedance injectors??
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oldcorollas | Sun, 14 December 2003 14:57 |
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Re: going from low to high impedance injectors??
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sideshow | Sun, 14 December 2003 21:47 |
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Re: going from low to high impedance injectors??
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ed_ma61 | Mon, 15 December 2003 07:16 |
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Re: going from low to high impedance injectors??
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thechuckster | Mon, 15 December 2003 08:02 |
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Re: going from low to high impedance injectors??
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sideshow | Mon, 15 December 2003 08:51 |
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Re: going from low to high impedance injectors??
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ed_ma61 | Mon, 15 December 2003 12:12 |
