Megasquirt Forum Area is for discussing Megasquirt EMS

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

Thread Tools
 
Search this Thread
 
Old 12-30-05, 10:54 PM
  #1  
Senior Member

Thread Starter
 
Join Date: Jan 2004
Location: Pittsburgh/Johnstown, PA
Posts: 476
Likes: 0
Received 0 Likes on 0 Posts
PWM flyback circuit not needed if running high imp injectors?

Do I need to install this since I am running high impedance injectors?
Old 12-30-05, 11:20 PM
  #2  
MegaSquirt Mod

 
muythaibxr's Avatar
 
Join Date: Sep 2004
Location: Maryland
Posts: 4,721
Likes: 0
Received 1 Like on 1 Post
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.
Old 01-10-06, 11:19 PM
  #3  
Full Member

 
norbak1258's Avatar
 
Join Date: Nov 2002
Location: Colorado
Posts: 183
Likes: 0
Received 0 Likes on 0 Posts
1988 turbo II is high impidance correct?
Old 01-10-06, 11:24 PM
  #4  
MegaSquirt Mod

 
muythaibxr's Avatar
 
Join Date: Sep 2004
Location: Maryland
Posts: 4,721
Likes: 0
Received 1 Like on 1 Post
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.
Old 01-11-06, 06:16 AM
  #5  
RX-7 Alumni

 
Rex4Life's Avatar
 
Join Date: Oct 2002
Location: Spacecenter Houston
Posts: 1,140
Likes: 0
Received 1 Like on 1 Post
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.
Old 05-09-07, 05:25 AM
  #6  
SAE Junkie

iTrader: (2)
 
Jobro's Avatar
 
Join Date: Mar 2005
Location: OZ/AU
Posts: 1,282
Likes: 0
Received 8 Likes on 5 Posts
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?
Old 05-09-07, 01:04 PM
  #7  
Rotary Enthusiast

 
renns's Avatar
 
Join Date: Oct 2001
Location: Ontario, Canada
Posts: 1,022
Likes: 0
Received 4 Likes on 4 Posts
Here's the Honda unit I'm using.

Attached Thumbnails PWM flyback circuit not needed if running high imp injectors?-honda-resistor-pack.jpg  
Old 05-17-07, 07:13 AM
  #8  
Junior Member
 
auricom's Avatar
 
Join Date: Apr 2007
Location: Dearborn Michigan
Posts: 11
Likes: 0
Received 0 Likes on 0 Posts
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.
Old 05-17-07, 08:58 AM
  #9  
MegaSquirt Mod

 
muythaibxr's Avatar
 
Join Date: Sep 2004
Location: Maryland
Posts: 4,721
Likes: 0
Received 1 Like on 1 Post
no, you don't have to do that unless you're using low impedance.
Old 05-18-07, 10:23 AM
  #10  
#include <stdhdr.h>

 
dfwrx7's Avatar
 
Join Date: Aug 2001
Location: Allen, Tx
Posts: 375
Received 3 Likes on 3 Posts
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.
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
trickster
2nd Generation Specific (1986-1992)
25
07-01-23 04:40 PM
alphawolff
1st Generation Specific (1979-1985)
17
11-17-15 05:57 PM
morataya
Microtech
1
08-16-15 09:39 AM



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



All times are GMT -5. The time now is 06:44 AM.