Seems like if you just trick the ECM into thinking the air is hot by moving the IAT sensor to the upper radiator hose (plastic tie wrap and duct tape) then you wouldn't have to give up as much HP but still widen the LeanBurn range. I have a CVT so no LeanBurn for me to mess with.
Theory #3- NO- the hotter the air=less dense air= less O2; results in less O2 in the exhaust gas,which is sensed by the O2 sensor, which then tells the ECU to lean the fuel mix=better MPG even when not in lean burn. Asuming that the O2 sensor, not the IAT, is the "final authority", once the engine is at operating temp, in fuel mixture and smog output.
ed
Theory #3- NO- the hotter the air=less dense air= less O2; results in less O2 in the exhaust gas,which is sensed by the O2 sensor, which then tells the ECU to lean the fuel mix=better MPG even when not in lean burn. Asuming that the O2 sensor, not the IAT, is the "final authority", once the engine is at operating temp, in fuel mixture and smog output.
ed
There might be less O2 in less dense air, but there is less nitrogen, and hydrogen, and all the other stuff. I don't think that less dense air will have any effect on O2 sensor operation.
MLN63,
I don't think moving the IAT to the upper radiator hose is a good idea. The ECU needs actual IAT to get proper fuel mix. If you always had the IAT running hotter than actual, you'd always be running lean, which isn't the same as being in lean burn. That would not be good. you wouldn't have the lean burn algorithm burning off NOx, and under heavy load, you coudl damage your engine. That is if you actually got it to run at an air-fuel ratio other than what the ECU wants. It might just correct the air-fuel ratio to where it should be using the O2 sensor. The O2 sensor is king in this game. I woudn't be surprised if it doesn't totally correct away from any IAT tricks to get to the air-fuel ratio it wants to run. Also, you might just throw a code.
I have had the IAT sensor moved to the upper rad hose in both my vehicles and get higher MPGs than if it is reading the actual air temp, since the sensor is reading cold when the coolant is cold I have no CELs and no drivability issues.
Better results are achieved at 130d than at 115d and no further improvement passed 130d.
The CVT vehicles don't have leanburn so the warm air mod will only produce less HP so you need to use more throttle for the same engine load.
I have had the IAT sensor moved to the upper rad hose in both my vehicles and get higher MPGs than if it is reading the actual air temp, since the sensor is reading cold when the coolant is cold I have no CELs and no drivability issues.
Better results are achieved at 130d than at 115d and no further improvement passed 130d.
The CVT vehicles don't have leanburn so the warm air mod will only produce less HP so you need to use more throttle for the same engine load.
Hmmm. Interesting. Perhaps you have effected it enough to lean it out to where the O2 sensor can't correct it back, but for some reason the ECU doesn't have an issue with that. I guess experience trumps theory in this case.
Need4Speed: I wouldn't say that your mod was for nothing. Using a larger throttle opening for the same load means it is easier for the engine to pull air past your throttle plate. I think the true indicator of whether or not all your effort was for nothing would be your difference in consumption. If it didn't change, then maybe it was all for nothing. You have said that you haven't noticed an improvement in your winter mileage when compared to summer, but that's definitely not an apples to apples comparison. Perhaps in a few months you'll know.
My late summer/early fall tank MPGs were in the 77 to 79 MPG range, made it the 40 miles to work many day at 84 MPG. Now I am struggling and this tank is showing 65 MPG, so I am down around 12-14 MPG due to the cold weather. This tank the average temperature has probably been around 15F, with a number of drives to/from work at -5F to +5F. We have not had a lot of snow, just mostly very cold temperatures. My commute does not really change either, traffic wise.
The cold temps also affect the battery, with it charging by itself to 86%, then discharging by itself just to warm it up.
I have seen so many posts that indicate that the colder temps dropped 6-8 MPG and the person adds the warm air mod to get back to normal. No such luck for me.
__________________
2001 Red CVT
19,351 miles lmpg 19.0 as of Oct 7, 2011
Best tank 78.9 MPG, 738.9 miles
Email dave@groe.us
I guess you don't have any data from cold weather before the mod?
I find the battery comment interesting. So you're saying that the battery will put itself through charge and discharge cycles just to warm the cells up? Is that just so that it will be able to perform better when needed? I wonder how much of a drain on mileage that is. I also wonder what temperature you have to get below before the battery starts wasting juice doing that. I've tried doing research on this, but the terms in the search are so abundant on this forum that it's hard to find any data on that phenomenon/algorithm.
All I found is this one here. The bottom of page 15 and top of page 16 hint at it.
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