Ok, in the interest of getting the most mpg, I've done a hot air intake mod off my (modified) cat shield, to the air box via a 2" flexible heat riser tube. Scangauge shows (in this cold weather here in Buffalo,) intake air temps of around 80-100 degrees, which seems to be the best (after using and playing with it for the last couple of years now.) Engine runs perfect at 195 or so, summer and winter. So with water temp and air intake temp being the same, why do I do better mpg-wise in the warmer weather? After kicking it around, I'm guessing the ambient air temp sensor (in the front bumper) might have something to do with it. Any thoughts? If so, what is it for exactly? If it does play into the equation, what if I mounted it inside the air box to fool the system that it is warmer outside than it actually is? Would this help? Could it hurt anything? For those in the know, thanks for your forthcoming advise!
Chris
I think the Temp sensor in the front bumper is primarily for the Climate control system to control autostop, so it probably doesn't affect the engine management. The Intake Air Temp sensor located on the intake pipe is what is used by the ECU for engine running.
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2002 Silver MT 225k miles LMPG - 60.8
Best Tank Distance = 722 miles @ 74.2
Ambient air sensor has been relocated by others on this forum. I believe it has two purposes, one is to provide input so the automatic climate control knows how to behave to provide the proper action to keep on top of the temperature to provide uniform comfort, and two, preventing the car from going into auto-stop with the climate control in demand, even in econ. Others have moved it and enjoy that they get auto-stop when they feel they should. I looked at it a bit and wasn't sure how to slip it on the other side of the radiator and until I figured it out, I didn't want to cut the wire mounts.
Edit: Posted same time as 02insight, pretty much same info.
So with water temp and air intake temp being the same, why do I do better mpg-wise in the warmer weather?
Summer gas has a higher energy content per gallon than winter gas. Also, hot humid air may give better mpg: I get better mpg on hot summer days than on cooler summer days, using the same summer gas, as long as it isn't so hot I need the AC.
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2006 MT
MIMA w/FAS module
various mods to driver
You're right about humid air; these cars love it. None of that in the Buffalo area when the temp is well below 32 degrees! Thanks guys! Question answered!
Chris
Winter mileage is worse because the engine runs longer with cold enrichment, snow and rain on the road increases rolling resistance, air is denser and more viscous increasing aero drag, oil and grease is thicker increasing mechanical drag.
No matter what you do to the car, it still has to push through cold dense air on wet or snowy roads trying to turn stiff tires and thick lubricants. Some battles you just can't win.
I've made several modifications that reduce the impact that winter has on my fuel economy. I'm getting 65mpg tank averages this winter, which is far better than it would be if I didn't try.
I've made several modifications that reduce the impact that winter has on my fuel economy. I'm getting 65mpg tank averages this winter, which is far better than it would be if I didn't try.
Of course things can be done. When the air is cold one can block off more of the grille. A block heater will warm the engine. Hot air intake is more important. Not everything can be compensated for but things can be done.
The biggest thing you can do is use forced auto stop, because the car will be much more hesitant to engage auto stop in winter.
There's also intelligent use of the heater controls for faster warm-up. A ScanGauge or similar helps with that.
When the snows that came with my car wear out, I'll install LRR snow tires.
Then there are mods that help year-round, but behave differently in the winter. Air is 20% denser in winter than summer, so aeromods become that much more important. IMA battery capacity is greatly reduced, so an assist/regen disable switch may have a greater impact. Regen is weak in the winter, but weight reduction and grid charging help reduce the need for regen.
If I had only three pieces of advice to give, it would be block your grille, install FAS + assist/regen disable, and drive with gloves.
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Ambient air temp sensor question for the "gurus"
