Dragon posted this in another thread, but I think it deserves it's own.

With the FC Datalogit you can change the inj size to 1600 and it shows on the commander and works.

 

ummm....yeehaw?

just kidding Igy

 

Pretty much yes, but you still need the resistors...

 

The stock injectors are 15 ohms..
The 1600's are 5 ohms...
If you don't put in the 10ohm resistors with the 1600's to make them 15ohms your car will run fine for a while until a couple weeks later when it burns up the injector driver in the power fc that is made to run 15 ohm injectors and your computer will be junk...

The resistors are only around $.020 ea and you only need 2...

Chris

 

This is just theory, so take it with a grain of salt, but...

Running 1300cc injectors at 54 psi base fuel pressure is equivalent to running 1600cc injectors at 40 psi base pressure, in that the same amount of fuel will be delivered by both setups with the same injector signal from the ECU.

So, it seems to me that the problem of running 1600cc injectors with the PowerFC (and with the limit of 1500cc from the Commander) could be solved by adjusting the primary injector size down in the same ratio that the secondaries are scaled down by. The PowerFC needs to know the RATIO of primary and secondary injector sizes to calculate the injector signal. The absolute sizes seem to be less important, because the effect is no different than running different fuel pressures. The PowerFC does not know what fuel pressure you are running, so it doesn't need to know the exact sizes of the injectors to work properly, either.

Another issue that I haven't seen addressed much is that "1600" injectors are usually 160 lb/hr injectors, which converts to 1680 cc/min rather than 1600.

I am not 100% sure of how the settings need to be changed so that the PowerFC can calculate things properly, but I am 100% sure that it can't do the job with 550/1680 injectors entered as 550/1500. I suspect that you might be able to leave the injector pulse correction value at 100%, but change the injector sizes to something like this:

Q-Pr = (1500/1680) * 550 = 491
Q-Sc = (1500/1680) * 1680 = 1500

My thinking is that by leaving the injector pulse correction value at 100%, your fuel maps may be able to stay the same as they are. However, since I don't really know how it uses these values, you might need to change the injector pulse correction value and re-do the fuel maps to get the injector signal right, but at least by entering the sizes so that the PowerFC knows the real ratio it seems possible for it to calculate the injector pulses properly. Perhaps someone from the datalogit team that understands how the PowerFC calculates the injector signal could comment on this.

And of course if the datalogit can be used to enter the real sizes, perhaps none of this matters! Get a datalogit and enter the real sizes.

-Max