This is what the tuner here in Denver states about the FIC...........
The problem with the FIC on this setup (and pretty much on most FIC cars) is not making power, its the driveability. Things like cold and warm start, light/moderate throttle, idle, etc. Making power is the easy part, its getting it act right when you're not WOT (i.e. 95% of the engine's time in a street car) where the FIC (or pretty much any other piggyback) just doesn't fit the bill. In general, I'd say that the older ecu's (OBD1) are actually easier to fool with a piggyback than the new ones (i.e. OBD2).
For example, When you put bigger injectors into a car, many times it needs a higher idle speed to maintain idle (warm, cold, depressing the clutch after a redline wot pull, etc.). Well, you can't raise idle speed with an FIC. The stock ECU tries to target a given idle speed, and you can't affect that part of the ECU's logic by simply fooling its input signals. Sure, you can add more air mechanically at idle, but the stock ECU will still pull air via the IAC to lower the idle. An OBD2 car might even throw a code if "too much air" gets base the throttle body at idle (i.e. it could think there's a vacuum leak).
Thoughts?
Some of his statement is true some is not at least with respect to the F/IC on a NSX. If you keep the power goal in the 450whp and less area the F/IC should handle the job. There are a few things you have to consider when putting the entire system together if the F/IC is the engine management tool you will be using. Injector size is a big factor in how easy the tuning process will be. I have found the 440-550cc injectors to be a sweat spot and are the easiest to setup. Go much bigger than a 750cc injector and things will start to get a lot harder.
The OEM O2 wires should not be wired into the F/IC, you should not need the O2 offset feature and if you think you will you should do a stand-a-lone ECU.
The F/IC should not be used on cars running more than 10psi of boost unless you are running higher octane fuels or Meth/water injection. The F/IC has a limit to the amount of retard (-10 degrees according to Chris at SOS) it can induce because it does not intercept all of the cam and crank sensors.
The OBDII NSX's do not use an IAC, they are drive by wire and the idle control is via the throttle blade, I have had zero issues in getting a NSX to idle and return to idle but I have not done one on a cam car, ported heads, or made any throttle body changes, those changes would cause some issues with the OEM ECU being able to idle.
IAT's are a huge issue to having a stable tune, the OEM ECU is very aggressive in trimming both fuel and timing due to IAT's, setup a well designed WTA intercooler and keep IAT's under control and the F/IC and OEM ECU will be much, much happier.
The NSX ECU is not that advanced and is not that hard to keep happy, most MIL lights are emmision related and are usually an electrical or mechanical issue. The biggest issue to getting a F/IC dialed in is the drive time needed to get the fuel trims stable in closed loop, idle and cruse will take some time ussually about 1-2 hours on the road and I have not found a way to get them done any faster or any other way than just driving the car and making changes to the fuel map untill it is stable. I have had little luck doing any drivability work on the dyno, the WOT stuff is easy and can be dialed in on the dyno in 1-3 hours the changes made in open loop are very stable and very predictable, at least they have been for me.
The F/IC may not be the best option for everybody but for me the best option is the F/IC as we have plug in OBDII emmision tests and without the OEM ECU running its readiness test we can not get a car to pass. For me its not to practical to pull injectors, remove/reinstall an ECU, return the car to stock fuel system, and drive around on eggshells for a few drive cycles every year to get plates renewed.
If you plan to stay under 450whp, under 10psi boost, and have emmision issues to deal with I would consider the F/IC to be a good option. However when/if the Infinity-10 ECU is released it may be worth making the move to a full ECU as even now the Series2 AEM is really acting as a piggy back on the OEM ECU. With that issue solved it may be worth the hassle of changing things out every year to get the added control. Might be smart to start off with the F/IC and save some money for the Infinity-10 instead of the Series2. Of course there are ECU options other than AEM but that opens up the same can of worms with emmision issues.
Dave
.........
