would there be any point to wiring in the optional ignition harness as it wouldn't be able to advance timing without the cam pos or crank pos with the emanage blue anyway...so what else would it do or be good for then on our cars? lastly regarding the injector harness, the only advantage would be to control the duty cycle of the injectors and control them individually right? but if only doing a simple air/fuel ratio tune, the main harness would be enough as it allows altering of the maf signal to change the AFR just as how the a safc would right, so what else would merit the install of the optional injector harness and it's additional abilities?

 

You have a basic handle on what the different harness do, now here are the reasons why. The basic harness is used to control the MAF meter, by adding or subtracting percentages in 1% increament. With this basic harness you an also use the injector scaling function to replace the factory injectors with larger ones with out the car running too rich and flooding. Once you scale down larger injectors you can only add fuel back using the MAF map to a small degree. The signals are so fast and precise comming from the MAF, that after too much negative to positive adjustment the signal is not smooth. (If I did some home work I could come up with an equation and formula to explain this point, but I have other pressing matters, maybe some others will chime in on a better explaination, but thats it in a nut shell.)
The injector harness is used only to increase the pulse width of the injectors. You cannot reduce the amount of time the injectors sqirt, only add. Once the injectors have been scaled back, then the addional injector harness adds fuel back at certain %s just like the MAF. At points where you are not in boost and driving in a normal manner, the injector harness boxes should be at zero. Once the car starts getting into boost, you can then adjust the proper settings in the 3rd quadrant, when the tps is past 50% and the RPMS reach 3000 or 3500.
The Ignition harness is used to retard timing when you reach boost to avoid detonation. When you increase cylinder pressure, heat causes the fuel to ignite before the piston is in the proper postion to start its down stroke. When the piston is too high in the rotation and the fuel ignites, you run the risk of burning pistions and valves.
One of the bad things about our cars is that when moving up in the RPM the range the computer automatically advances timing to gain power when N/A. When boosting this can be catostrophic, thats when you burn holes in the pistons and blow head gaskets.
If you are running less than 8psi of boost, the ignition harness is not apsolutely necessary, however I was able to add 17hp by just adjusting timing after all other tuning was completed. Try buying an extra 17 hp for $30 any other way.

Hope this helps a little.

Choray