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Megasquirt PWM flyback circuit not needed if running high imp injectors?

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Old Dec 30, 2005 | 10:54 PM
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PWM flyback circuit not needed if running high imp injectors?

Do I need to install this since I am running high impedance injectors?
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Old Dec 30, 2005 | 11:20 PM
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you don't need to, but if you have the parts I'd install it anyway in case you ever want to run low-impedance injectors.
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Old Jan 10, 2006 | 11:19 PM
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1988 turbo II is high impidance correct?
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Old Jan 10, 2006 | 11:24 PM
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even if it isn't, the rx7 came with resistor packs stock on all the years that are low-impedance...

This means that either way you can run no problem without the extra flyback circuitry.
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Old Jan 11, 2006 | 06:16 AM
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From: Spacecenter Houston
Originally Posted by norbak1258
1988 turbo II is high impidance correct?
Yes that's correct. If for some reason you end up pulling the injectors, it's easy to check. Just measure the resistance across the injector--high impedance will be 10 ohms or greater, low will be less than 5 ohms.
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Old May 9, 2007 | 05:25 AM
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Can someone post a picture of this fabled resistor pack?

Any differences electrically to a normal carbon wound resistor?

I'm planning on using 89-91 High Impedance Turbo injectors 550cc
and 870cc Siemens injectors which are low impedance?
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Old May 9, 2007 | 01:04 PM
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Here's the Honda unit I'm using.

Attached Thumbnails PWM flyback circuit not needed if running high imp injectors?-honda-resistor-pack.jpg  
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Old May 17, 2007 | 07:13 AM
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if you use high impedance injectors don't you have to use PWM to lower the injector duty cycle? instead of a constant pulse width during the entire injector cycle, you need a PW of a few nanoseconds to open the injectors needle/armature asm, then you turn the PW on and off rapidly for the rest of the duty cycle. the PW will fluctuate so fast that the needle will not be able to close, but the injector coil will not get overworked. then of course when the cycle is over, you stop the rapid PW and bring the current back to zero, closing the needle.
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Old May 17, 2007 | 08:58 AM
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no, you don't have to do that unless you're using low impedance.
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Old May 18, 2007 | 10:23 AM
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From: Allen, Tx
Originally Posted by muythaibxr
even if it isn't, the rx7 came with resistor packs stock on all the years that are low-impedance...

This means that either way you can run no problem without the extra flyback circuitry.


I don't think that's true on the GSL-SE's. My -SE was definitely low-Z through the factory harness. I just added resistors to my MS harness.
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