as far as i know, our fuel map has:

1)an open loop - 0rpm - 4000rpm. in this situation, everything will vary, and the injectors will put in as much/as little fuel as it deems necessary.

2)closed loop - 4000rpm - redline. in this situation, the ecu will tell the engine and injectors to run only 1 strict map.

now this is the part i don't quite understand fully. if the air intake is aftermarket, won't the engine run lean after 4000rpm(given the intake provides more air than stock intake), since no matter how much air is going into the engine, the stock ecu will only run that 1 fuel map and inject the same amount of fuel regardless?

please help me understand this, and please correct any information that is wrong ^^

 

ANYTIME you add aftermarket product's,you should upgrade(tune)your ECU.If it's only an intake(and exhaust) your adding,you will be fine.

 

From my understanding, Open Loop occurs under 2 conditions:

1. under Wide Open Throttle (WOT)
2. during cold start ups (when the engine is cold)

The ECU runs under a preset Air to Fuel Ratio.

Close Loop = ECU set the A/F ratio according to what the sensors are detecting.

 

you have it backwards, closed loop is where the ecu makes short term and long term fuel changes to keep the stoichiometric ~14.7:1 air to fuel ratio to try to get the best fuel economy and emissions.
open loop is when the engine runs off of a premade fuel map from the factory. figuring out when the ecu switches from closed loop and open is a little tricky, it's based on a few variables: RPMs, MAP, throttle position, and O2 temp.
when you install an intake or exhaust it would be best to get your car tuned for it, but it really doesn't matter, when Honda makes the fuel map, they have to account for the people in the higher elevation, cold climates, etc... so they make it safe for everyone. So the little bit of extra air from the intake would still be in spec.

 

bluecivic107 is correct, Open loop on cold starts and WOT. closed loop any other time.
thats why Drive Clean (ontario emissions program) doesn't test at WOT, because its one of the only times that engine emissions arent regulated (the other obviously being a cold start-up)
open-loop is when the ECU just runs at 14.7:1 AFR or less for one of two purposes; max power, or to aid in catalyst light-off and warm-up.
closed-loop is when the ECU reads the other sensors (O2, TPS, etc) to determine the best AFR for the given load.
thats why some mods don't have a large effect, the computer is negating their effects when its in closed loop.
in closing, in open-loop the ECU wont inject the same amount of fuel regardless, it will inject an amount that will give an ideal 14.7:1 AFR for max power (WOT) or something a little richer for cold starts.

 

Having nothing to do with this thread at all:
LMAO! That is the best name EVER! You need to change your avatar pic to the green one though
You may now resume your previous discussion...that is all

 

So, how much tuning IS possible on our system? I'm not really familiar with what's available for Honda tuning, but I built an EFI system for my old Plymouth so I have a pretty good handle on what has to happen. I don't anticipate needing to tune on my Fit much at this point, but I'm looking in to the potential of a supercharger in a few years.

FWIW, I think with regard to AFR under open/closed loop, any time the engine is running in open loop, the computer is using a look-up table to calculate how much fuel to inject at a given moment. Closed loop is trying to achieve 14.7:1 AFR to keep the catalytic converter happy and emissions low. This may not apply to engines that run with wide-band O2 sensors full time, as you could easily program the AFR desired at the MAP/TPS/temp point in question.

Anyone know if Fits use WBO2's?

HF

 

In open loop, it injects a certain amount of fuel regardless, because it doesn't read O2 readings in open loop so how would it know that it's 14.7 :1 AFR?(14.7:1 is way LEAN for WOT it's more like ~13:1 or ~12:1)

 

no just a narrow band