rotarypower101

iTrader: (1)

So does the PFC run low impedance injectors with resistors correctly or not?

Is using the resistors just a way to make them work?

What is the difference in the way they operate/distribute fuel?

If I am using the datalogic I can completely bypass (not install) the resistors right?
How does it do this are they (10 ohm 20 watt resistors/10 ohm 10 watt resistors) built into the datalogic?

How much better is it to use the 1300s instead of low impendence 1600s, assuming that there is no issue with the 1300s sticking or not working properly?

I was talking to Ralf Friend (Exessive motorsports, groundzero) and it sounded like he was saying that 1600s work but are just not as accurate at putting in the fuel as high impendence1300s would be (my interpretation of what he was saying)

Obviously many others are using them so they must work fairly well. Right?

I am running the GT 35/40 and was thinking about using 850 primaries and 1300 secondaries. These will work for my HP goals but I am not sure if using 1300s is the right path, because I have read a couple of posts that say stay away from the bored out 850s to 1300s.

I have been scowering the forum for answers but haven’t come up with much on some of my questions.

What will be the advantage to running the high impendence over the lows if any?

I am leaning towards the 1600s because they are much less expensive, new, and I haven’t heard any bad stories about them sticking closed or problems with running the resistors/datalogic.

Thanks for any help

cewrx7r1

iTrader: (2)

I have only run stock injectors with the PFC, 550/1200s, but I do know about electronics, so here are some basic facts.

First the basic law of DC electricity. Injectors runs DC but because it is pulsating at a high rate, it does have some AC affects but we will omit these(impedance, capacitance, and reverse EMF).

E(volts) = I(current) * R(resistance).

The stock resistance is 13.8ohm for a Mazda injector.
I do not know if the ECU supplies 12 or less voltage so lets use 12 volts. I know the alternator supplies almost 14 volts but this is irrevalent for our discussion as is the supply voltage. The laws still work the same.

Thus omitting the resistance of the wiring an asumming it is 0 ohm, we have 12 volts = I * 13.8 ohms.
Or I(current) = 12/13.8 = .87 amps.

watts(power) = I * E = .87 *12 = 10.44 watts.

Thus this is the basic load range the ecu was made to run per injector.The circuits might be able to run hicher current without problems but I do not know their safe maximum current/power. So now to your questions.
***************************************
"So does the PFC run low impedance injectors with resistors correctly or not?"
Yes it can if the extra current flow is within its design range. This will have to be answered by someone who has actually done it. It would work up to the point of overheating then burn up if the load was too high.
Most like would happen at higher fuel load requirements as the injector cyclic rate goes higher.

"Is using the resistors just a way to make them work?"
They will work anyway up to the point of overloading the ecu control circuits. The added resistor is used only to keep max current flow within the save range for the ecu circuits.

"What is the difference in the way they operate/distribute fuel?'
None except a large injector injects more fuel.

"If I am using the datalogic I can completely bypass (not install) the resistors right? "
Might burn up/overload the ecu.

"How does it do this are they (10 ohm 20 watt resistors/10 ohm 10 watt resistors) built into the datalogic? "
Really do not understand this question. Both of these resistors will have the exact same affect if placed inline with a lower resistance injector. The diff is there power/heat handling capacity. 10ohm/20watt can handle twice the current of a 10/10. 20 watts is twice the value of 10.

"How much better is it to use the 1300s instead of low impendence 1600s, assuming that there is no issue with the 1300s sticking or not working properly?"
The question really is, what is the power requirement for a lower than 13.8 ohm injector. If the installed resistor reduces total current flow such that the power used by the injector is too low, it might not function at the full rated flow rate. The R value given in E=IR
can be (R = R1 + R2) R1 being the risistor and R2 being the injector. If R1 = R2 than each drop half the power of the total circuit which might be too low for the injector.
You will need to know the operatinal range for the low resistant injector. It is never a problem with a higher resistance injector becaue it will alwasy get it max required current/power with out overloading the ecu.

"I was talking to Ralf Friend (Exessive motorsports, groundzero) and it sounded like he was saying that 1600s work but are just not as accurate at putting in the fuel as high impendence1300s would be (my interpretation of what he was saying)'
See above.


"I am running the GT 35/40 and was thinking about using 850 primaries and 1300 secondaries. These will work for my HP goals but I am not sure if using 1300s is the right path, because I have read a couple of posts that say stay away from the bored out 850s to 1300s."
Bullshit fairy tells. Anything might not work sometimes if not correctly made or modified.

"What will be the advantage to running the high impendence over the lows if any?'
Less load on the ecu this less heat build up.

rotarypower101

iTrader: (1)

"How does it do this are they (10 ohm 20 watt resistors/10 ohm 10 watt resistors) built into the datalogic? "

"Really do not understand this question. Both of these resistors will have the exact same affect if placed inline with a lower resistance injector. The diff is there power/heat handling capacity. 10ohm/20watt can handle twice the current of a 10/10. 20 watts is twice the value of 10."

Maybe I am misinformed but dosnt the datalogic have the ability to omit the proper resistors, and have a setting in a datalogic menu to set it up for 1600s?
Or is it just the proper setting so the pfc adjusts for the 1600 injector as opposed to the 1500 limit? (this may be my misunderstanding)


so if what you said is correct then the reason for using the 10 ohm resistor is to bring the watts close to the same as stock?

“1-3ohms =low impedance;12-16ohms=high impedance”
from “Sixrotors”

https://www.rx7club.com/forum/showth...impedence+ohms


“E(volts) = I(current) * R(resistance).”

I= 12 volts / (3ohm injectors+10ohm resistors)= .923 amps


“watts(power) = I * E = .87 *12 = 10.44 watts.”

watts(power) = I * E = .923 *12 = 11.08watts

which is only 6% off the original numbers. And am sure it could be refined much better if necessary.

Thank you very much for sharing your knowledge cewrx7r1

David