Gas Mileage Issues
12-21-2012, 01:15 PM
#1
Thread Starter
Join Date: Dec 2012
Location: Al
Posts: 12
Gas Mileage Issues
I posted this previously but was told to post in this section. I bought my first mustang this summer and had no problems until i got my oil changed at the ford dealership about 2 months after i bought it. Ever since that oil change my miles per gallon have been steadily dropping. Even when i drive more conservatively it doesnt improve my mpgs. I noticed that when I do rev a little higher and the mpgs drop it never goes back up. The only way the average mpgs goes up is if i reset it every time it gets stuck. Even though i reset the average miles per gallon the miles to E stays the same. When i first bought the car i was getting about 320 miles on a full tank but since the oil change i have been getting about 230 miles on a full tank which I thought was really low. Im not sure if it was something the dealership did or if it was just a coincidence that this started happening. Please help because I am a struggling college student and I knew gas was going to be pricey but i didnt think i would have to fill up every week!!!
12-21-2012, 03:49 PM
#2
2nd Gear Member
Join Date: Oct 2012
Location: TN
Posts: 263
That's a loss of almost 7MPG (90 miles/13 gallons), assuming a 13gallon fill up (which is what mine usually holds when I fill). Something seems amiss for sure. FWIW, I usually get around 300 before I fill, that's mixed city/hwy.
12-21-2012, 04:28 PM
#3
Beofre i chime in with good advice my first comment will be... YOU OWN A MUSTANG... Gas mileage should NOT be a concern.
Now, based on how you drive, shift, etc has a lot to do with Gas Mileage... DO NOT trust the Lie-o-Meter.
The best way to do it is through the tried and true method of, filling up, going to 1/4 tank, fill it up again, record how many gallons it took, repeat process 3-4 times and that will give you a more accurate reading.
However, if you're driving spirited here and there you have to factor that in. You should drive it consistently throughout this fill-up process.
I have a 13, and my HWY MPG = 18, because I hammer it to work (90 mile commute one way), I fill up every other day. I am used to this and again, I bought this car knowing full well, it is not a YARIS/Prius and the best I would probably do if I drove it at 65-70 is about 23.5mpg
However, my right foot has an issue, it is a heavy and that 65-70 reads more like 85-90 or 95-100
Now, based on how you drive, shift, etc has a lot to do with Gas Mileage... DO NOT trust the Lie-o-Meter.
The best way to do it is through the tried and true method of, filling up, going to 1/4 tank, fill it up again, record how many gallons it took, repeat process 3-4 times and that will give you a more accurate reading.
However, if you're driving spirited here and there you have to factor that in. You should drive it consistently throughout this fill-up process.
I have a 13, and my HWY MPG = 18, because I hammer it to work (90 mile commute one way), I fill up every other day. I am used to this and again, I bought this car knowing full well, it is not a YARIS/Prius and the best I would probably do if I drove it at 65-70 is about 23.5mpg
However, my right foot has an issue, it is a heavy and that 65-70 reads more like 85-90 or 95-100
12-21-2012, 08:44 PM
#4
Thread Starter
Join Date: Dec 2012
Location: Al
Posts: 12
Beofre i chime in with good advice my first comment will be... YOU OWN A MUSTANG... Gas mileage should NOT be a concern.
Now, based on how you drive, shift, etc has a lot to do with Gas Mileage... DO NOT trust the Lie-o-Meter.
The best way to do it is through the tried and true method of, filling up, going to 1/4 tank, fill it up again, record how many gallons it took, repeat process 3-4 times and that will give you a more accurate reading.
However, if you're driving spirited here and there you have to factor that in. You should drive it consistently throughout this fill-up process.
I have a 13, and my HWY MPG = 18, because I hammer it to work (90 mile commute one way), I fill up every other day. I am used to this and again, I bought this car knowing full well, it is not a YARIS/Prius and the best I would probably do if I drove it at 65-70 is about 23.5mpg
However, my right foot has an issue, it is a heavy and that 65-70 reads more like 85-90 or 95-100
Now, based on how you drive, shift, etc has a lot to do with Gas Mileage... DO NOT trust the Lie-o-Meter.
The best way to do it is through the tried and true method of, filling up, going to 1/4 tank, fill it up again, record how many gallons it took, repeat process 3-4 times and that will give you a more accurate reading.
However, if you're driving spirited here and there you have to factor that in. You should drive it consistently throughout this fill-up process.
I have a 13, and my HWY MPG = 18, because I hammer it to work (90 mile commute one way), I fill up every other day. I am used to this and again, I bought this car knowing full well, it is not a YARIS/Prius and the best I would probably do if I drove it at 65-70 is about 23.5mpg
However, my right foot has an issue, it is a heavy and that 65-70 reads more like 85-90 or 95-100
12-21-2012, 10:53 PM
#5
6th Gear Member
First of all, the on-board tends to be highly inaccurate (I say tends to be because the vast majority are off by about 1-2 MPG to the high side while a rare few are dead-to-nutz on) so hand calculating at each fill-up is a must if you want a TRUE average MPG as opposed to an average relative MPG.
With that said, when you bought the car, did you immediately (or at all) reset the on-board? If not, then you were averaging all the previous data points such that ANY LIVE TIME change in your fuel mileage was masked by the thousands of prior data points. Regardless, you should be resetting the onboard AND hand calculating at each fill-up. Also, trying to figure your fuel mileage by "miles per tank" is useless unless you literally run it 'til empty each time (which is plain stupid). All too often I read of folks complaining of poor fuel mileage and it turns out they've done something to change the PCM settings for gears or tire O.D. which impacts the on-board or something else related to using the on-board properly.
Of course, there IS the possibility of a real issue and not necessarily one caused by the dealer; only YOU can begin troubleshooting to begin ruling out the more likely items that can CAUSE a significant drop in fuel mileage. Begin looking at tire pressure (you'd need to be running a tire near-flat to see that kind of drop, though), dragging brakes, intake/exhaust restrictions, driveline issues...
With that said, when you bought the car, did you immediately (or at all) reset the on-board? If not, then you were averaging all the previous data points such that ANY LIVE TIME change in your fuel mileage was masked by the thousands of prior data points. Regardless, you should be resetting the onboard AND hand calculating at each fill-up. Also, trying to figure your fuel mileage by "miles per tank" is useless unless you literally run it 'til empty each time (which is plain stupid). All too often I read of folks complaining of poor fuel mileage and it turns out they've done something to change the PCM settings for gears or tire O.D. which impacts the on-board or something else related to using the on-board properly.
Of course, there IS the possibility of a real issue and not necessarily one caused by the dealer; only YOU can begin troubleshooting to begin ruling out the more likely items that can CAUSE a significant drop in fuel mileage. Begin looking at tire pressure (you'd need to be running a tire near-flat to see that kind of drop, though), dragging brakes, intake/exhaust restrictions, driveline issues...
12-22-2012, 12:26 AM
#6
Thread Starter
Join Date: Dec 2012
Location: Al
Posts: 12
I didnt reset anything when I got the car. The only thing I could possibly think of is that the dealer reset everything when they changed the oil. I will calculate my average miles per gallon on my next fill up to see what it actually is. The only thing that really bothered me was the fact that my car was consistently saying I was getting 12 mpgs until i actually realized you could reset the mpgs. Before I ever reset ANYTHING my cars miles to E dropped to 199 miles on a full tank and I know that is beyond ridiculous. Like I said this all started right after the oil change. I will try all the suggestions everyone has listed and hopefully I will get to the bottom of the actual problem thanks.
12-22-2012, 04:26 AM
#7
I understood the fact that i wouldnt get very good gas mileage driving a mustang but if i had have had this problem with the gas mileage from the beginning I would be completely ok with it but this has just started happening. I am cleaning my air filter now to see if that maybe was the issue.
But also keep in mind a lot of short trips eats up gas, and even so when yu don't run the car, you can lose gas to evap.
12-23-2012, 06:56 AM
#10
6th Gear Member
Short trips, a lot of stop and go, ANY frequent, heavy acceleration will all take a significant toll in fuel mileage.
If there is ANY chance that the dealer reflashed the PCM, then it's possible your onboard isn't calculating dustance correctly (which is direct input to the fuel mileage value). Check your speed against a GPS.It should be within about 2 MPH.
SeaFoam is a good idea. I typically run Techron thru the tank about once of oil change (that's about 8k-10k miles for me) as Preventive Maintenance but will use the SeaFoam if I suspect a problem.
If there is ANY chance that the dealer reflashed the PCM, then it's possible your onboard isn't calculating dustance correctly (which is direct input to the fuel mileage value). Check your speed against a GPS.It should be within about 2 MPH.
SeaFoam is a good idea. I typically run Techron thru the tank about once of oil change (that's about 8k-10k miles for me) as Preventive Maintenance but will use the SeaFoam if I suspect a problem.