How Air Temps affect MPG - Ford Mustang Forum
 
LinkBack Thread Tools
post #1 of 6 (permalink) Old 01-31-2017 Thread Starter
PONY Member
 
Nelsoncp21's Avatar
 
Joined: Dec 2016
Posts: 254
 
Garage
How Air Temps affect MPG

So this winter we've had some really crazy up and down weather here in VA. One day it's 30 degrees and 2 days later it's 60 and then back to 30. This has been going on all through December and January. I've been closely watching my gas mileage since I bought my Ecoboost back in Aug. Up till November I was hanging right at 28 MPG average. Then the colder weather hit and it dropped down to nearly 27mpg average. I just chalked this up to the switch to winter gas additives. Recently I've noticed though on days where the air temp is 50+ I'm getting between 27.6 to 28 MPG. If the temps are below 50 I'm seeing decreases somewhere between 27 and 27.5. I use 93 octane from the same gas station each time. The only variance is air temps.
So my question is what exactly is causing this? I am not an expert but my initial thought is colder air being denser causes the computer to adjust the A/F ratio. More or denser air meaning more fuel being injected. Is this thought process correct or do you think it's something else?

Nelsoncp21 is offline  
Sponsored Links
Advertisement
 
post #2 of 6 (permalink) Old 01-31-2017
BOSS Member
4.6L Member
 
JonR2006's Avatar
 
Joined: Jun 2012
Location: St. Louis
Posts: 4,989
             
Garage
I'm noticing the same thing but I personally think it's effected by more than just temperature...tire pressure changes, driving habits for each tank, gas quality, type of traffic throughout the span of a tank, etc...

Are you adjusting the tire pressure to be the exact same every day? Every 10 degrees is one PSI (up or down). You could be running lower tire pressures which tends to negatively effect MPGs.

There are probably a lot of things contributing to what we are seeing other than the temperature drop. You are seeing such a minimal affect (maybe 1 MPG at the most). Too many variables to consider that I'm not comfortable attributing it to just one of them.


Matthew 26:52-54 / Go Pack Go!

1987 Mustang GT Hatchback - 2V Mod Swap In The Works

1997 Lincoln Town Car, PI Intake/Cams, Sofa-On-Wheels, "Fat Tony" we call it

2001 GT Convertible - D1SC / Geared / Cammed / 440wh 400wt - TOTALED 2/2019
JonR2006 is offline  
post #3 of 6 (permalink) Old 01-31-2017
PONY Member
 
AlloyPony's Avatar
 
Joined: Jun 2014
Location: The Bluegrass State
Posts: 739
 
You're seeing a smaller drop than I would expect.

In winter, lots of things happen. First, fuel retailers switch to "winterized" fuel. It's got additives that help prevent freezing in your tank, but it also has less energy per liter so your fuel economy will drop. Second, the car will run in closed loop mode for a longer period of time because it takes longer to reach operating temperature. This increases fuel usage. Third, the colder temps. increase fluid friction, which robs horsepower, which increases fuel usage. Fourth, cold air is more dense, which pushes upon your car with more force, which increases fuel usage while on the highway.

It's almost impossible to get your best MPGs during winter. I typically see a 2 MPG decrease with my cars and trucks both during winter.

2003 Mach 1 - TR3650 - Ford Performance aluminum shaft - Mac O/R H-pipe - Airbox modification - 17% tint

Gone but not forgotten:
2001 GT auto in Zinc Yellow-Flowmaster mufflers - Pypes O/R H pipe-Eibach Sportline springs/Koni STR.T shocks-AMR wheels w/ 315/35 MT Street Comps-FR 3.73s-Blankenship Performance tuning-Steeda Under-drive pulleys-BBK CAI-AcuFab 70mm TB
AlloyPony is offline  
 
post #4 of 6 (permalink) Old 01-31-2017
Apprentice
Classic Member
 
HuntingKy's Avatar
 
Joined: Oct 2009
Location: Sonora,KY
Posts: 213
 
I have owned a 2012 Ecoboost since new and every winter I notice a drop in mileage.
I have also had the though that the cold, dense air causes a richer mixture to be used.
HuntingKy is offline  
post #5 of 6 (permalink) Old 01-31-2017
PONY Member
 
Coosawjack's Avatar
 
Joined: Mar 2016
Location: Beaufort
Posts: 423
 
It's the fuel in Winter since colder air is more dense and you should actually get much more power in cold air than hot air......fuel being the same!!
Coosawjack is offline  
post #6 of 6 (permalink) Old 01-31-2017 Thread Starter
PONY Member
 
Nelsoncp21's Avatar
 
Joined: Dec 2016
Posts: 254
 
Garage
Thanks. Sounds like for the most part y'all are thinking along the same line as me.
I drive the same route the same time of day every day so there really isn't much variance there.
As I stated in the original post I have been using the same gas from the same station since they switched to the winter additives so that's not it. Plus I can see the variance even off the same tank of gas since the weather around here has been like a rollercoaster.
I would agree with the tire pressure statement but that was the first thing I looked into. In fact when the cold weather first kicked in I put air in my tires. While the pressure may vary from day to day when I first start it seems to be staying constant after a few miles on the road and they heat up so that has been pretty consistent.
I had never given much thought to the friction of the lubricants. Not sure how big of an impact this is though as I always warm up the engine and check the oil temp before I start driving. I'm sure there is a slight impact though.
Good stuff though. I appreciate the feedback.
Nelsoncp21 is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Ford Mustang Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a VALID email address for yourself, otherwise you will not receive the necessary confirmation email needed to confirm, validate and activate your new AFM member account.

Failure to provide a VALID email address, will result in the cancellation of your new AFM member account registration.

Email Address:
OR

Log-in













Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome
 


Search Engine Friendly URLs by vBSEO 3.6.1