That’s untrue. That’s the whole point of a o2 sensor. The sensor reads the amount of fuel that is being burnt to the ecu can compensate for how much fuel the injectors will dump into the engine. If not enough fuel is not being burnt from let’s say a clogged air filter then the ecu will back off on the fuel that is being dumped into the engine. When you add a cone filter the more air that is being sucked into the intake will cause the ecu to dump more fuel into the engine. Yes Honda uses a closed loop system to a point that’s what we call a base map. The engine temp o2 sensor and timing tells the ecu how much of the air fuel ratio is off from the base map. Now if you ran a dummy o2 sensor then yes the amount of fuel that is being squirted from the injectors will ALWAYS be the same because the exhaust reading will NEVER change. Being at a higher altitude can cause the engine to lean out a bit which will get you better gas mileage. Since the air is thinner. So saying the modification of the intake will not change any of the gas mileage is wrong because it does in one way or another.

 

I'm sorry, you're completely incorrect; OBD-II systems keep the air to fuel ratio spot on for any given driving dynamic regardless of altitude or the configuration of the intake upstream of the throttle body. In fact, MAP based systems are, if anything, even more accurate than MAF based systems in this regard. Like it or not, modifying the intake and/or changing altitude will not affect an engine's fuel efficiency.

The above said, given the reduced aerodynamic drag on the vehicle's body when at altitude, that WILL noticeably improve fuel economy.

 

ok if you say so

I guess I just don't what I'm talking about. If what your saying in true why does honda use all the sensors to correct your a/f ratio? I guess we can just do away with them and the car would run 100% spot on. No matter of what altitude temperature or driving conditions your driving in. But we will go with that *face palm*

 

A lot has happened since I while I was gone. So...You have a car that idles like crap, loses power slowly over time, you change the air filter, gets nominally better, you change the oil with fingers crossed, nothing improves. You change the plugs, still nothing. You go down to the local auto store and in a last ditch effort you by sensor cleaner and shoot all your O2 sensors with it, the car runs normal again. Sure wish my wifes car work how you are describing Shipo, would have made my life easier and a lot cheaper.

 

Bottom line is...My car gets better gas mileage since I took out the preheater box.

Cold air expands faster and more voilently when compressed and ignited within a cylinder requiring less fuel to achieve the desired effect. Increased volume and flow of air WILL create finer atomization of fuel through induced/increased turbulence within the intake manifold (Physics).

Here's a noodle boiler for you. In many cases you can increase HP by replacing your throttle body with a smaller one (more so on motorcycles but it applies to cars as well) !?!?!?!?!?! Why is that? Do you know? Hint: It's physics again.

 

Clearly you need a course in combustion science; what you describe is a scientific and physical impossiblity.

Fact, a cold dense charge will yield more power (albeit at a rich A/F) than a similar volume of warm air.
Fact, a warm charge will yield a lower BSFC than a cold charge due to the superior fuel atomization of the mixture.

If you don't like those facts, hey, I'm only the messenger.

No surprise there; a throttle body which is too large can reduce (or eliminate) optimal intake resonance which will in turn reduce power within a given RPM range.

 

How is what I've written not clear; the "Closed Loop" nature of the intake system uses primarily the MAP sensor (or MAF depending upon the make of the engine) for the basic fuel map, and then other sensors (primarily O2) for the fine tuning of the mixture.

Slice it and dice it any way you want, the air to fuel ratio will not change whether you're running say a 20% throttle setting while tooling along on a straight and level road at 65 mph when the atmospheric conditions are 59°F with a density altitude equivilant to 10,000' MSL, or whether you're running that same 20% throttle setting due to having a heavily clogged air filter and you're rolling along at the same speed and OAT but with a density altitude of Sea Level.

Long story short, altitude will do nothing to change the BSFC of the engine; the only reason vehicles will get better fuel economy at altitude is wind resistance against the body of said vehicles.

 

Well I guess we will agree to disagree

 

Agreed

 

Yeah, normally the O2 sensor has limited authority to adjust fuel rate. Otherwise you'd have ONLY the O2 sensor & don't need anything else.

Really, the other suite of sensors can respond more quickly so they're used for primary control. Either MAF or MAP/RPM depending on the carmaker's "tradition".

And the O2 sensor really can't measure "mixture". It can only measure difference in oxygen partial-pressure inside vs. outside the exhaust pipe. Quite a few situations can fool the O2 sensor, for example a misfiring cylinder. The sensor will read excess O2 in the exhaust, but the engine isn't really running lean. Excess O2 along with unburned fuel means it isn't burning, but the O2 sensor can't measure the presence of unburned fuel.

It's also pretty common for the control system to go to open-loop at high loads. The EPA cycle doesn't extend into very high loads, so above a certain load they will increase the fuel rate for a bit of charge-cooling. That's more common in turbos, but I think it's sometimes done in NA engines.