Ok, I'm sure this has been asked 100 times, but my search wasn't useful.

I replaced the intake & air box with a DIY cold air intake BUT I kept the original "tube" that the sensor is in, so it should be reading the proper air/O2, correct?

Thinking of doing exhaust (axle back). Since I still have the stock intake sensor setup, is an ECU retune required/recommended?

I am assuming (correctly or incorrectly) that since the intake sensor is still factory, it is also "accurate". So the ECU shouldn't need to "de-tune".

I love this stuff but the info I hear is confusing and conflicting. When/why/how does the ECU recalibrate to factory and how does that overcome any advantages of better breathing?

Separate question, does simply using higher octane make any performance difference? Or is that only a factor in higher compression engines where the ECU can "compensate" for lower octane?

Any info is greatly appreciated.

 

basically it will be a noise maker because from what i understand no mod on this car is truly useful unless you get yourself a FIC. the cars ecu pushes it back to getting the best fuel economy possible... shitty i know

 

yet i have gone over a second faster in the quarter mile between fully stock and where i am now.

it dials cruising efficiency down, not aggressive driving

 

don't do a fart can axelback or straight pipe the freeway drone will kill you and it feels like you lose low end alot go with a nice tanabe muffler or on the lower end price wise a megan muffler youll be happy in the long run if you end up doing a cat delete or b pipe unless you like the sound of bees and tons of noise like a diesel truck as your car goes slower then a prius and back to what you asked no ecu tune is needed and I run 91 but I doubt its making a difference but ive always ran 91 in all my Hondas only cause I love them or they required it

 

with a stock exhaust and muffler delete, my car did not drone or kill your hearing on the highway. sounded good when cruising and going around town, still sounded OKAY when beating on it.

Now that I have the cat delete, aka WeaponR crap, it sounds GODAWFUL

My car demands a good quality muffler and a long resonator. Its horrible

 

A.:
Q1: correct.
Q2: not required nor possible. Only way to retune this ECU is a reflash.
Q3: correct.
Q4: quoting the manual, "This system constantly adjusts the ignition timing, reducing the amount of HC, CO and NOx produced."
And it also adjusts fuel based on airflow. When it adjusts is constantly. Why? Because Honda programmed it that way. How it adjusts is rather complicated.

Q5: my answer is yes, though many disagree.
Q6: the Fit engine is high compression, and the ECU does adjust to low/high octane.

 

YEAH I looked into the full headers but without a turbo ,supercharger or a cam setup I don't see the point I feel like it would be bog city with no power in low end I kept the primary cat just removed the second one and the resionator with staright 2 inc piping and kept the stock muffler car is very responsive no lag in any part of the powerband has some rice tones at about 3-4000 rpm but nothing crazy like the dohc engines out there with headers (I know not many will agree with me but I like the rice noise if I wanted a deep sound I would have bought a mustang ) only thing I plan on doing would be a nice shinny muffler after that im done trying to gain anymore hp not like you feel it much anyways and on to sparco seats,mugen parts and carbon wings hood and lips and all the things to make my fit pretty and some tein springs im over the driving my sponge on wheels( And I wish skunk2 made a intake manifold and throttle body that would be amazing )

 

just keep the ecu stock and use 87.

 

Sounds like a fartcan, don't ya think? Suitable for old farts, like ....... me??!