Tannerpford

I just had cam phasers put in two months ago and thinking about it that is the time when it started. I have always thought it ran rich I always had a lots of black build up on the tail pipe and sometimes when I would start it on a cold mornings it would smoke for a sec. They tried to tell me that it was just steam but I know the difference. I hope they did something and can fix it but I doubt it since I am now off warrantynow.

LugN8R

I am going to offend a lot of people by saying this but I heard this from a very good mechanic that worked for freightliner and went to Wyo-Tech. If you put an aftermarket high flow air filter system on your newer truck the computer will change the air/fuel mixture so it compensates for the increased air, causing more power and less mileage. I would like to see a debate on this. This was not my opinion, but it makes sense to me.

Tannerpford

I got 2 mpg better when I put my airaid on and that was two years ago.

VanoFord

I have had a Stage 2 AEM Cold Air Kit for quite some time on my 06 Supercrew. My mileage started to drop but I never put 2 and 2 together. I have gibson headers, true duals, TB spacer... how could i be losing mileage? So then I researched and picked up a Diablo MAFia and now, 15 in the city, 22+ on the highway, sometimes 25 (but how often do we go 55). Anyone that has alot of mods should pick up this mod for sure. THERE IS A DIFFERENCE BETWEEN THE ENGINES SO MAKE SURE YOU GET THE CORRECT ONE. thats my 2 cents, feel free to return any change

JerrfyLube

Since when?

Colder air creates a denser fuel\air mixture which in turn means more power...which again, if you drive conservatively, means slightly better mileage. Once its up to opperating temp, it should be every bit, if not more efficient as it is in the summer months. Different fuel blends can effect mileage, but if your seeing substantial drops, you need to start buying gas from someone else. But from my experience, the biggest killer of mileage is your right foot...not the fuel your putting in it. Its easy to blame crap mileage on gas but its RARELY the cause.

Some of my highest MPG numbers have been recorded in winter months...but probably, because i tend to tow my toys a lot less then...

posttal

I'm glad..in a way..to see this thread.
My mileage dropped from 14.5 to 9 roughly about a month ,month and a half ago.I noticed it when I updated my Gryphon with a new 87 octane performance tune and reset my gages to show mileage.After a week of noticing lower mileage I went back to the stock 93 performance tune...with no change.I left the gryphon setting with the 93 octane tune since its winter and heat and ping is not an issue..and because when I first installed it my mileage was pushing 15mph.
Now after see all the others with mpg issues I'll join in with hopping its just weather related since the air is denser.Hopefully it will come back up in the spring.
Oh,I'm in cleveland,Ohio..its 23 outside as we speak with 6 inches of fresh snow on top of the already 8-9 inches.

Ruprecht

Rup's Conspiracy Theory: (cue the X-Files theme)

With a tough economy and fuel companies looking for ever greater profits, gas station owners are getting pinched. As a result, many are resorting to making 'adjustments' to their pumps and mixing in 'additives' to their fuels to get back a couple cents per gallon.
Along with winter blends, the fuel is less efficient, and we are paying for 26 gallons when we are really only getting 25. As a result, our fuel economy appears to drop suddenly.

JerrfyLube

Got any credible sources to back those claims up??

CrashTECH

Definitely a conspiracy theory. That just isn't true. There is ZERO blending at the pumps. The stations just can't support this. There are different blending properties and additives for the winter, but this is due to EPA emissions requirements and engine warm up needs. The fuel is less efficient but that has nothing to do with stations wanting to sell you more gas. Gas stations don't make more than maybe 3 cents a gallon. If you bought 26 gallons you got 26 gallons in your tank.

Fuel economy drops in the winter because of the change in blending and additives for the winter months.

http://www.startribune.com/cars/11354696.html

The answer mentions "time to temperature" and the density of the air alone. Which are very valid physics based reasons.

Energy required to raise temperature: LINK

Q=m*C(T1-T2)

Q = Energy
m = Mass
C = Specific Heat (a measure of thermal conductivity)
T1 and T2 are start and end temperatures, on the Kelvin scale. (delta t)

Table of various specific heats for metals.

So you just plug and chug! You can see how ignoring everything else, the delta t is a big player.

If the temperature of the engine block is 0* C (freezing point of water) and you need to get it put to the normal operating temp of over 95 and under 220*F (35-105*C) you can see that you are changing the factor of energy required by many multiples of 10. Delta T from freezing to normal temp is going to be around 90. Now if it is a little warmer, say 25*C (approximately room temperature) the difference is 90-25 = 65.

So converting to Kevlin and assuming that mass = 1 and specific heat = 1.

Freezing = 0*C = 273K
Room Temp = 25*C = 298K
Operating Temp = ~90*C = 363K

Q = (90) From freezing to normal (363-273)
Q = (65) From room temp to normal (363-298)

So in colder weather, you can see that the energy required to reach operating temp is going to be greater. More fuel is used during the warm up time, so lower MPGs will be attained.

Tannerpford

Ya I know that the cold weather has a lot to do with it but I have a bad bog when I step on it and I know that isn't the cold weather. What could that be and now this tank I put Costco gas in and it jumped up to 15.3 and I did some 4 wheeling in the snow. I was getting 12 then it started to climb I don't know if it pulled out of it or what I hope so but I would really like to know what is going on with it. I know the chip is reading correctly because I calculate it every tank and the chip reads within a tenth.