The way I understand this is heating the air going in on a MAF system would confuse the ecu. The fuel and ecu work together for the best mpg. You can cover the front to build a little heat in the radiator but the intake grabs air from the side anyways. The winter gas has less btus and more is required. Also isn't heating the intake opposite of what you want. It was 22 around here a few days ago and my IAT temps were 32 highway and went up to 40 at idle. Here this will explain it Testing a warm air intake (WAI) - MetroMPG.com . Keep in mind this is a MAP system and Not A MAF.

 

The real problem is gas is supposed to be 2 dollars not 4. At 2 dollars most people would not complain. I am with you on trying to figure ways to improve mpg.

 

What root problem are we trying to solve?

Fuel atomization? Heat the fuel. See what happens.

Fuel mixture? Do we think that the mixture is off when it's colder? What data is there to support this?

I would venture a bet that a good part of mileage gains in warm / less dense air have to do with reduced drag.

As far as rich / lean conditions - we need to get our heads out of carburetor mode. EFI systems tend to read intake air temperature. If they read it, they're adjusting for it.

Not trying to say there won't be gains. Just not sure that everyone understands what they're trying to "fix".

 

The ECU is typically aiming for stoich outside of high load situations.

With warmer air there is less fuel required. Thus less is consumed.

The idea being to raise IATs so less air (by mass) passes over the MAF and subsequently less is injected. This also makes it easier to light the mixture off.

This is something that could be accomplished simply by keeping your foot off the go pedal. Though warmer air on start up would reduce fuel consumption by letting you get off the fatter part of the Coolant Temp v. Fuel Enrichment tables and enter Closed Loop operation sooner.

But if the ambient temps are low, the coolant/intake temps will be cold anyways. This is where blocking off half the radiator and other techniques come in. But again, just taking it easy on the throttle would achieve comparable if not equivalent results for most.

 

No 'problem' really Just curiosity about how IAT affects fuel consumption, everything else being equal... and if there's any tinkering that can be done to take advantage of that. (Always looking for an excuse to tinker, right? )

this ^^^

 

DiamondStarMonsters said what needed to be said.

And that is the point. There's not usually much magic to this stuff - but tons of myth.

I'd personally be curious about mappings that keep you at stoichio at all loads. Some preliminary observations (bargain OBD2 -> Bluetooth adapter and an Android handheld using Torque non-free) seem to show that 80% throttle is where the current mapping transitions ABRUPTLY to power rich - a targeted 12.4:1 I think.

I'd also be curious about properly designed exhausts and their MPG implications. I know that 80's and early 90's injected Hondas benefited noticeably from proper exhausts MPG wise as much as they did power-wise. Had personal experience with the Lightspeed stuff (4-2-1 headers, can't recall what the rest of the system was like) working out nicely with stock mappings.

Anyway, I doubt that most of us are smarter than Honda. They probably picked a nice compromise - a very nice compromise.

 

Stoich at all loads would not really be do-able without a stratified direct injection that would make it more like a homogenous charge compression ignition motor.