Piss Poor Gas Mileage
Senior Member
Joined: Apr 2004
Posts: 4,424
Likes: 0
From: Motor City
Yeah, a 2 mile drive w/ 5 lights ain't pretty on the fuel gauge....
I have a 17 mile commute, 5 lights & about 11 miles slow & go freeway. That results in my 15mpg tanks every week. Nice long road trips @ 70-80mph results in a tad over 17mpg's.
All these numbers still rival if not beat my '99 Expy w/ 4.6L. I love this truck!
I have a 17 mile commute, 5 lights & about 11 miles slow & go freeway. That results in my 15mpg tanks every week. Nice long road trips @ 70-80mph results in a tad over 17mpg's.
All these numbers still rival if not beat my '99 Expy w/ 4.6L. I love this truck!
Senior Member
Joined: Dec 2003
Posts: 146
Likes: 0
From: Northern AZ
Let me ask you this...
I'm going to take a highway test drive to see if I see a difference. How long should it take the info center to reflect better mileage? Does it adjust pretty quickly?
The one time I tried resetting while cruising along (at 40, not freeway speeds), it hit 22 mpg. On the trip I mentioned with the 18.8 mpg average, I put gas in, ran around in town some, then hit the road the next morning. The average included about 10 miles in town and patrolling the garage at Seatac looking for a place to park, then driving home.
To answer your question, it will improve immediately from the initial readings when it's on the highway, but it may take a 100 miles or so to get a decent highway average. It climbs quickly for a while, then gradually adds a tenth every few miles. On my trip, it pretty much settled in at 18.8 and didn't fall any once it reached that point.
I'm going to take a highway test drive to see if I see a difference. How long should it take the info center to reflect better mileage? Does it adjust pretty quickly?
The one time I tried resetting while cruising along (at 40, not freeway speeds), it hit 22 mpg. On the trip I mentioned with the 18.8 mpg average, I put gas in, ran around in town some, then hit the road the next morning. The average included about 10 miles in town and patrolling the garage at Seatac looking for a place to park, then driving home.
To answer your question, it will improve immediately from the initial readings when it's on the highway, but it may take a 100 miles or so to get a decent highway average. It climbs quickly for a while, then gradually adds a tenth every few miles. On my trip, it pretty much settled in at 18.8 and didn't fall any once it reached that point.
Senior Member
Joined: May 2004
Posts: 5,409
Likes: 1
From: Sunny FL
Originally posted by cowboy_cash
Does anyone suggest the best gas to use i.e 87, 91, or 93?
I have a SupCab FX4 5.4L 3.73 w/K&N drop in filter. All the rest is stock.
Does anyone suggest the best gas to use i.e 87, 91, or 93?
I have a SupCab FX4 5.4L 3.73 w/K&N drop in filter. All the rest is stock.
Originally posted by Superchips_Distributor
Hi Brian42,
Thanks for your post!
Actually, "72 Mustang's" original post pointed out that he was going to be using the 9100 - which is our custom Micro Tuner with performance tuning. So that being the case, as I stated originally, yes, there *is* more power to be had by having us tune for 93 octane instead of 91 octane.
Additionally, it is NOT automatically & always true that using higher octane fuel is a complete waste of money on the stock tuning - though to be fair, I'm kinda-sorta "splitting hairs" here, as I'd be the first to say that I wouldn't spend the additional money on additional octane that the motor is not specifically tuned for, as you usually don't get enough additional mpg to *justify* that additional expense in these F-150's.
In reality, that actually depends on how the knock sensor system is set up (calibrated) in each individual vehicle's computer code (PCM revision/calibration), and that varies widely in these trucks. For example, some will allow as much as 8 more degrees of timing as long as the knock sensor does not detect detonation (and here we're talking about one specific form of detonation, "pre-ignition") - but the other catch is the actual *rate* at which that timing comes in. It's usually slow enough (say, only 1 degree every 2 seconds at the same TP & load) that it's just not worth spending the money as you don't get enough additional fuel mileage to offset that cost - UNLESS the truck is actually tuned for it's use. There are some F-150's (a good number) whose knock sensor system calibration cannot add any timing when detonation is not detected, while others can add only another 2 degrees of timing, but can do it pretty quickly - again, this varies widely in these F-150's. You can take 20 trucks of the exact same configuration & model year, and have 13 different knock sensor calibrations.
I generally *do* agree that as long as the engine is not specifically tuned for the higher octane in the borderline knock table, it's not going to be worth spending the additional 20 cents per gallon as compared to what can be had (both in terms of raw power and fuel mileage gains) if the higher octane is actually *tuned* for. These F-150's have more different PCM revisions each model year than virtually any other vehicle made - sometimes *hundreds* of different revisions each model year alone, and they vary widely in certain areas - such as how certain limiters are effected, how the knock sensor system is calibrated, etc. Just FYI........
By the way - on the subject of fuels & energy content - higher octane fuel does not automatically have "less energy." On the other hand, it is also false that higher octane premium fuels will always automatically have a *higher* energy content than "regular" fuels, as some assume (and as some oil companies have advertised/marketed) - more often than not, when there is a difference, it's usually in favor of the higher octane fuel. There is not any kind of "rule-of thumb" *either* way.
When dealing with *quality* fuels, the actual BTU content per gallon (or per lb.) of fuel usually does not vary much regardless of octane (in the 87-100 octane range, R+M/2). The actual energy content of gasoline is expressed by the oil company/refiner in terms of the number of BTU's per gallon - say, 110,000 BTU's per gallon, or 98,000 BTU's per gallon, etc. - and that is not "automatically" increased or decreased (all else being equal) based solely on the octane rating.
Another point that comes up from time to time regarding fuels & higher octanes is the burn rate - once ignited, the flame front propagates itself across the combustion chamber at roughly the same speed regardless of octane (again, when we're talking about fuels in the 87-100 octane range R+M/2), generally speaking - but getting it *LIT* - actually INITIATING the burn of the A/F mixture takes more time - both in real time and in degrees of crankshaft rotation, as octane rating goes up. This is *precisely* why it's generally considered close to a waste of money to use more octane than the motor is tuned for, more often than not - and I'd be the first to say not to bother using more octane than the motor is tuned for, I do agree with you on that, certainly. Using significantly more octane than the engine is tuned for will actually *reduce* power and fuel mileage, and can also cause MIL's, etc. just as the owners manuals for most of these vehicles mentions.
With higher octane, it's not just that we can make more power & mpg *if* we add timing - proper tuning dictates that we *must* add more timing to the motor to compensate for now much longer it takes to *initiate* the burn of the higher octane A/F mixture. The spark plug needs to get it's current with the piston further down the bore (BTDC) so that peak cylinder pressure still occurs with the piston the same approximate number of degrees *down* the bore (ATDC) - otherwise the engine doesn't make the power it should, and won't get the fuel economy it should, either - this is why most of these vehicles owners manuals specifically instructs *not* to use premium gas, as they are originally tuned for 87 octane from the factory.
In tuning, the BTU content ("energy") of the fuel makes every bit as much difference, if not more, than just it's octane rating. A low energy 93 octane fuel can be out-performed by a higher-energy 92 octane fuel, for example. Or take methanol-based fuels (far different from gasoline) - now they have a *very* high octane rating, but have only about 50%-70% of the BTU content per gallon of gasoline.
Just some quick general FYI...................
Hi Brian42,
Thanks for your post!
Actually, "72 Mustang's" original post pointed out that he was going to be using the 9100 - which is our custom Micro Tuner with performance tuning. So that being the case, as I stated originally, yes, there *is* more power to be had by having us tune for 93 octane instead of 91 octane.
Additionally, it is NOT automatically & always true that using higher octane fuel is a complete waste of money on the stock tuning - though to be fair, I'm kinda-sorta "splitting hairs" here, as I'd be the first to say that I wouldn't spend the additional money on additional octane that the motor is not specifically tuned for, as you usually don't get enough additional mpg to *justify* that additional expense in these F-150's.
In reality, that actually depends on how the knock sensor system is set up (calibrated) in each individual vehicle's computer code (PCM revision/calibration), and that varies widely in these trucks. For example, some will allow as much as 8 more degrees of timing as long as the knock sensor does not detect detonation (and here we're talking about one specific form of detonation, "pre-ignition") - but the other catch is the actual *rate* at which that timing comes in. It's usually slow enough (say, only 1 degree every 2 seconds at the same TP & load) that it's just not worth spending the money as you don't get enough additional fuel mileage to offset that cost - UNLESS the truck is actually tuned for it's use. There are some F-150's (a good number) whose knock sensor system calibration cannot add any timing when detonation is not detected, while others can add only another 2 degrees of timing, but can do it pretty quickly - again, this varies widely in these F-150's. You can take 20 trucks of the exact same configuration & model year, and have 13 different knock sensor calibrations.
I generally *do* agree that as long as the engine is not specifically tuned for the higher octane in the borderline knock table, it's not going to be worth spending the additional 20 cents per gallon as compared to what can be had (both in terms of raw power and fuel mileage gains) if the higher octane is actually *tuned* for. These F-150's have more different PCM revisions each model year than virtually any other vehicle made - sometimes *hundreds* of different revisions each model year alone, and they vary widely in certain areas - such as how certain limiters are effected, how the knock sensor system is calibrated, etc. Just FYI........
By the way - on the subject of fuels & energy content - higher octane fuel does not automatically have "less energy." On the other hand, it is also false that higher octane premium fuels will always automatically have a *higher* energy content than "regular" fuels, as some assume (and as some oil companies have advertised/marketed) - more often than not, when there is a difference, it's usually in favor of the higher octane fuel. There is not any kind of "rule-of thumb" *either* way.
When dealing with *quality* fuels, the actual BTU content per gallon (or per lb.) of fuel usually does not vary much regardless of octane (in the 87-100 octane range, R+M/2). The actual energy content of gasoline is expressed by the oil company/refiner in terms of the number of BTU's per gallon - say, 110,000 BTU's per gallon, or 98,000 BTU's per gallon, etc. - and that is not "automatically" increased or decreased (all else being equal) based solely on the octane rating.
Another point that comes up from time to time regarding fuels & higher octanes is the burn rate - once ignited, the flame front propagates itself across the combustion chamber at roughly the same speed regardless of octane (again, when we're talking about fuels in the 87-100 octane range R+M/2), generally speaking - but getting it *LIT* - actually INITIATING the burn of the A/F mixture takes more time - both in real time and in degrees of crankshaft rotation, as octane rating goes up. This is *precisely* why it's generally considered close to a waste of money to use more octane than the motor is tuned for, more often than not - and I'd be the first to say not to bother using more octane than the motor is tuned for, I do agree with you on that, certainly. Using significantly more octane than the engine is tuned for will actually *reduce* power and fuel mileage, and can also cause MIL's, etc. just as the owners manuals for most of these vehicles mentions.
With higher octane, it's not just that we can make more power & mpg *if* we add timing - proper tuning dictates that we *must* add more timing to the motor to compensate for now much longer it takes to *initiate* the burn of the higher octane A/F mixture. The spark plug needs to get it's current with the piston further down the bore (BTDC) so that peak cylinder pressure still occurs with the piston the same approximate number of degrees *down* the bore (ATDC) - otherwise the engine doesn't make the power it should, and won't get the fuel economy it should, either - this is why most of these vehicles owners manuals specifically instructs *not* to use premium gas, as they are originally tuned for 87 octane from the factory.
In tuning, the BTU content ("energy") of the fuel makes every bit as much difference, if not more, than just it's octane rating. A low energy 93 octane fuel can be out-performed by a higher-energy 92 octane fuel, for example. Or take methanol-based fuels (far different from gasoline) - now they have a *very* high octane rating, but have only about 50%-70% of the BTU content per gallon of gasoline.
Just some quick general FYI...................
Junior Member
Joined: Oct 2004
Posts: 3
Likes: 0
From: Germany
Originally posted by jpdadeo
Hey, cowboy_cash read this post about gas and octane. It explains why you should use the octane your engine is tuned for. Superchips_Distributor posted it back in June of this year. Hope this helps!
Hey, cowboy_cash read this post about gas and octane. It explains why you should use the octane your engine is tuned for. Superchips_Distributor posted it back in June of this year. Hope this helps!
