Locutus wrote::shock:
even better.
how do you tune with a narrowband? just make adjustments to keep it in the stoichiometric range?
sorry for the slow reply.
first off i would say that i have some reservations about your planned course of action. sticking in a wideband with a simulated narrowband output, and then using the dfa to tune that simulated narrowband output (with the guidance of the wideband via datalogging on a computer)... it just seems like a very convoluted process to me. why not just tune off the narrowband - because at the end of the day, you will be using the dfa to modify one or the other narrowband signals.... so why not just stick with the oem sensor / signal.
this is the umpteenth time i've gone over this , i should probably give it it's own thread to refer to in future.. save me having to type it out every time.
anyway.....
dfa built and installed
el cheapo jaycar AFR guage built and installed
ok so in the above shots you can see the gauge in closed loop cycling between green (lean) and yellow (rich), with several red leds in between . the mid point of the red leds is somewhere near stoich.
so when you put the boot in we go open loop and the car goes rich (yellow leds). so you take note of the corresponding tuning points on the dfa, and simply adjust these points until the yellow leds don't light up anymore.
i did this by doing laps of 2 on/off ramps of the western ring road here in melbourne, stopping in between to make adjustments. took me half an hour or so. i leaned it out to the 2nd last red light on my afr... it gave a noticeable improvement in power. probably could have gone further but i figured better safe than sorry.
later on i replaced my stock injectors (215cc from memory) with some big 460cc injectors, in preparation for a turbo install. the car would barely run when i first started it, coughing and spluttering as it was drowning in fuel. it took about 5 minutes tuning with the dfa in the garage to get it to idle and cruise... then took it back out to the freeway on ramps to tune again. another 20 / 30 minutes of WOT tuning and it was back to it's old self.
ok so i don't have any dyno charts to measure my results but another forumite , phil / manga_blue followed the same procedure in tuning his na8 with the dfa / narrowband afr meter combo. he recorded his setting and then zeroed out his dfa. then put his car on the dyno , had it dyno tuned and ended up with a tune that was almost exactly the same as his initial tune.
so yeah, for a lightly modded car i reckon you can get by with a pretty simple , cheap solution. for a heavilly modded car, a megasquirt or something is probably better but there ya go. you don't need to do much i reckon, the mazda engineers got it pretty right to start with, they just added some richness for safety, which can be easilly dialled out with the dfa.
