I posted this over at freshalloy also.
As some of you know, my plan thus far for my KA-T has been to use a SDS EIC (Simple Digital Systems Extra Injector Controller) controlling 4 extra MSD 50#ers in a seperate fuel rail (JWT), welded into the intake manifold runners.
I was going to tune the setup using the LM-1 wideband sensor, but as I'm thinking about the setup, I'm wondering how it is that I am going to be able to fine tune the AFR when I need to. The injector controller works in 2 ways: you can tell it at what boost (manifold air pressure) to turn the injectors on, and you can also control the fuel "gain," by determining at what rate the amount of fuel spray increases per RPM/boost increase.
My (theoretical at this point) problem is that the fuel is added only in a linear path. That is, once the initial spray times and amounts are determined, the spray rate at any time is determined as a function of that number and the imputs it receives. I am wondering, however, if this is going to cause me a problem if my AFR is NOT linear. I have never done any real tuning before, but I imagine air/fuel ratios kinda fluctuate, spiking here and there etc. If I find a spike in my AFR at say, 3000 RPM, I will have no way of correcting it with this system without adding fuel to the ENTIRE RPM range, see what I mean?
Am I missing something, or is this a real problem I should consider? WD, I know you have done a lot of tuning with extra injector setups... am I just making up problems or is this something you've come against?
Tuning with SDS EIC
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WDRacing
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Sorry I haven't been online much, since i leave tomarrow for the states. The SDS is very similer to the system that I'll be using with all of my turbo kits. The system works very well, since it only increases fuel duty cycle when boost increases via the map sensor. So the stock injectors which are run off of the stock ecu will control all the non boost variables. I know you already know all this, I'm just saying it to keep my head straight...heh. I don't think you'll have any lean conditions once you install the system and have it tuned accordingly. The system does limit your fine tuning over the entire rpm range. But it does a pretty good job of controlling fuel under boost.
The hardest part is getting the initial tuning done, obviously run pig rich to start then lean out the injectors as you go. Atleast the LM1 lets you datalog, so you'll have a complete rpm/boost graph to work with.
That doesn't really answer question huh...I'd suggest if you do run into a small lean spot, that you increase the duty cycle for the entire rev range and sacrifice the rich condition it creates for the rest of the range.
Let me know when your gonna start your tuning process, I'll help if I can. Hoepfully I'll be up and running by then and have some data for you to use.
WD
The hardest part is getting the initial tuning done, obviously run pig rich to start then lean out the injectors as you go. Atleast the LM1 lets you datalog, so you'll have a complete rpm/boost graph to work with.
That doesn't really answer question huh...I'd suggest if you do run into a small lean spot, that you increase the duty cycle for the entire rev range and sacrifice the rich condition it creates for the rest of the range.
Let me know when your gonna start your tuning process, I'll help if I can. Hoepfully I'll be up and running by then and have some data for you to use.
WD