2Lucky2tha7

iTrader: (3)

If anyone has seen my recent thread "Ridiculous stumble during injector staging ", then you know that I am having injector problems. So, considering that my secondary aftermarket injectors may be the problem, I'm thinking about getting the 1st gen yellow top 680cc low impedance injectors. My current setup is a streetported 4-port with a series 5 rotating assembly (9.7:1 rotors, full racing beat exhaust, etc. I am currently running 760 cc secondaries, but I was getting up to 150% duty cycle, which is pretty ridiculous. The lowest PWM I ever got it down to was 10.0 while the engine was hot, but once it got cold, it would constantly burn out the injector fuses and was VERY hard to start. Actually, it couldn't stay running at all. The only way I'm able to drive around now is if I set it to 20.0 or higher. I also have to use a 15 amp fuse for the injectors as well. When I wired up the harness, I ended up connecting all 4 12V injector wires to a much larger gauge wire, to my fuse box as well. But I doubt that that is the main problem at all, because I was originally using the original harness's 12V supply to the injectors. Regardless, they act the same either way. If I get the 680's, do you think that they will supply enough fuel for my setup, and will they somehow lower my duty cycle and help to fix the problem? I'm also using a TII fuel pump with a good fuel filter and fuel pump sock. I'm wondering if the 680's will be enough, because when it's getting down to 13 AFR's at higher rpm's, it's actually VERY fast, and much faster than a stock TII.
Also, as for MUYTHAIBXR's previous questions in my other thread:
(1): My ground wire setup is a chain of being connected to the battery, alternator body, engine block in 2 places, and the firewall in 2 places. All my grounds from the Megasquirt are grounded at the battery.
(2): The transistors do have the Mica insulators between them and the heatsink.
(3): There are no shorts in my wire harness, and it was thoroughly wrapped tightly in electrical tape, and I have checked it for any shorts, as well as where all the connections are. This didn't start happening until I changed from the stock high impedance 460cc injectors and the PWM was set at 25.5. Obviously, I changed out the injectors because my engine was being starved of fuel in the higher rpm's.

Anyway, any comments or suggestions? Do you think the 680's will help, or will they supply enough fuel for my setup? If not, what other injector options should I consider?

Brian

muythaibxr

The absolute EASIEST thing to do would be to find some high-impedance injectors, and stop having to mess with the PWM settings.

You could also grab a resistor pack off of another rx7 that has them.

I think the actual size of your injectors is fine, it's the fact that you can only set one set of PWM settings, but really need to be able to set the PWM settings differently for your primaries vs your secondaries.

Ken

renns

As Ken said, the resistor pack will make your life so much easier. Go to the local wreckers and grab one. If you can't find a Mazda part, the Honda/Acura units are very easy to get to, on the strut tower or firewall on the driver's side. Snip out a bit of the harness as well, and you can then wire it in with the stock Honda plug. I've used this type on a couple installations, and it works great. It also has a die-cast aluminum housing that looks nice when cleaned up. Pic below:

2Lucky2tha7

iTrader: (3)

In the meantime, I will be looking for a resistor pack. But I'm just curious, what bigger high impedance injectors can I find that aren't too expensive? Right off the bat, I only know of the stock series 5 TII 550cc ones.
Also, would you happen to know off hand where the resistor pack is in the series 4 engine bay?
Thanks,
Brian

muythaibxr

Off the top of my head, I think it's in the front passenger side part of the engine bay. Underneath where the AFM and air box and all that stuff would normally go.