Bumping an old thread if ya'll don't mind. I've decided to dive head first into fine tuning my own FIC in my ODB1 91. I'll likely get a base tune done first with Bisimoto locally but my gut tells me it will take me hours and hours of fine tuning to get it running optimally.
Have some questions:
1. How does the F/IC compensate for altitude at say 6000ft? Dave mentioned it has it's own MAP sensor. Is that built-in the F/IC case or is that an external sensor to measure manifold pressure, say at boost? I've read other Honda ECUs have a built in barometer inside the case but not sure if the NSX does. I'd be surprised if it didn't. At wide open throttle on a stock ECU the ECU reads not the boost pressure in the manifold, but the pressure in the ECU case at altitude advances the ignition and leans the fuel. This is not what you want in a boosted car if you want reliability. This is my current working assumption so i'm a bit confused how to tune for this.
2. I've read that there may be a 2D and a 3D method for controlling a Meth kit. Has anyone had success with using perhaps Boost and IAT to trigger? Or perhaps a 0-5V progressive trigger so the spray can be controlled gradually? I've read some installations where the Meth is ON as soon as the F/IC sees boost. Just looking for a more robust 3D method of controlling the Meth. (Actually i'll be using 80/20 so it'll likely be mostly water)
3. It seems the common assumption with the base CTSC tune (RRFPR, boost-a-pump, etc) is that it relies on the factory ECU to retard the timing, richens fuel when IATs get high. Is there a way to "undo" this with the F/IC? It seems during normal driving conditions (unboosted) my IATs hover around 100-140degs. I'm assuming at these temps the ECU isn't retarding timing nor richening fuel. With Meth/Water it seems the best we can cool these CTSCs is around 160degs and at this temp any more spray yields diminishing cooling results. My assumption is at 160 (likely 180+ at the track) the factory ECU will still pull timing and run fuel fat. Just trying to conceptualize how the F/IC can compensate against this condition...
4. Lastly, might be a dumb question, but the F/IC doesn't requires an input from a Wideband O2, right, but is it optional? If a UEGO was added into the system can the F/IC make dynamic adjustments based on the AFR at that point in time? It was mentioned earlier the the FIC can intercept the O2 signals as well. I'm assuming that's the factory narrowband O2 yes?
Thanks much for any input. Hope to return the favor someday!