Zetec on 91 octane
When using high Octane someone times the formula between a 91 or 93 octane could be the difference between a good idle and a great idle, either way. Depending on temperatures, the 91 could offer superior idle quality and part throttle response, where as the 93 might not as it's burn time is ever so slightly longer. Just saying.
If this is a standard Zetec, then this could be a sign of carbon buildup on the valves/pistons as well.
If this is a standard Zetec, then this could be a sign of carbon buildup on the valves/pistons as well.
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There is absolutely no advantage(1) to using higher octane gasoline if the engine does not require it. In fact, you may experience a small loss of power, as the detonation does not occur at the precise time that the engine is set for. If your engine is designed for 87 octane gasoline, then it should run best with that.
(1) Except to BP, Shell, or whatever company you buy from!
(1) Except to BP, Shell, or whatever company you buy from!
"Old Guy's" SVT:
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Incorrect. The PCM looks at the knock sensor and keeps advancing timing until it starts to pre-ignite. With a higher octane level, the pcm is able to advance the timing farther than on lower octane levels thus allowing a more complete burn of the fuel in the combustion chamber. This will increase fuel economy and sometimes make the car run smoother. Cost wise from 87 to 91, it is not worth the extra 1-3mpg you will get. Just my .02oldoutboardjim wrote:There is absolutely no advantage(1) to using higher octane gasoline if the engine does not require it. In fact, you may experience a small loss of power, as the detonation does not occur at the precise time that the engine is set for. If your engine is designed for 87 octane gasoline, then it should run best with that.
(1) Except to BP, Shell, or whatever company you buy from!
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Oh contraire, Mr. Mechanic - unless this particular PCM is programmed to take advantage of higher octane (many aren't). For example, Chrysler minivan V6's will run on any old swill, and higher octane gas will only cause them to have heartburn. Another thing: If your "normally runs great, designed for 87 octane" engine seems to suddenly need higher octane, that's an indication of other issues.FocusMech.73155 wrote:Incorrect. The PCM looks at the knock sensor and keeps advancing timing until it starts to pre-ignite. With a higher octane level, the pcm is able to advance the timing farther than on lower octane levels thus allowing a more complete burn of the fuel in the combustion chamber. This will increase fuel economy and sometimes make the car run smoother. Cost wise from 87 to 91, it is not worth the extra 1-3mpg you will get. Just my .02
"Old Guy's" SVT:
2004 CD Silver 3-door w/blue interior (one of 244 in that color scheme in 2004)
Build #879 of 1,978
Mods: JRSC+BBK; C-F-M Rear Engine Mount; FSWERKS Stealth Exhaust
2004 CD Silver 3-door w/blue interior (one of 244 in that color scheme in 2004)
Build #879 of 1,978
Mods: JRSC+BBK; C-F-M Rear Engine Mount; FSWERKS Stealth Exhaust
oldoutboardjim wrote:Oh contraire, Mr. Mechanic - unless this particular PCM is programmed to take advantage of higher octane (many aren't). For example, Chrysler minivan V6's will run on any old swill, and higher octane gas will only cause them to have heartburn. Another thing: If your "normally runs great, designed for 87 octane" engine seems to suddenly need higher octane, that's an indication of other issues.FocusMech.73155 wrote:Incorrect. The PCM looks at the knock sensor and keeps advancing timing until it starts to pre-ignite. With a higher octane level, the pcm is able to advance the timing farther than on lower octane levels thus allowing a more complete burn of the fuel in the combustion chamber. This will increase fuel economy and sometimes make the car run smoother. Cost wise from 87 to 91, it is not worth the extra 1-3mpg you will get. Just my .02
Being you mention "unless", you simply don't know for fact. Whereas mech does.
The other part you don't see mentioned much, if at all, is how the 'adaptive learning' plays into ignition timing, among other things.
Basic fact is, yes better fuel can aid in more power / more timing in every single Ford EEC-V. How much will vary on many things and might not be noticed at all. ... take an old SBC/SBF, +1* can't be felt at all. Same thing with newer cars, but that doesn't mean it's not helping something somewhere (lowering PW's for instance).
--John
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Yeah, it's helping something somewhere, alright: Helping BP's & Shell's bottom line. Helping to keep your wallet slim.iminhell wrote:How much will vary on many things and might not be noticed at all. ... take an old SBC/SBF, +1* can't be felt at all. Same thing with newer cars, but that doesn't mean it's not helping something somewhere
"Old Guy's" SVT:
2004 CD Silver 3-door w/blue interior (one of 244 in that color scheme in 2004)
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Build #879 of 1,978
Mods: JRSC+BBK; C-F-M Rear Engine Mount; FSWERKS Stealth Exhaust
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Yep the gas companies love it when you burn the non regular gas. Probably costs them pennies per gallon if that to give it just a little more octane.
BTW love the new handle Jim
BTW love the new handle Jim
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What the......? Oh well, if the shoe fits.Patalrob wrote:BTW love the new handle Jim
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If you think about it, premium gas has always been 20-30 cents more per gallon. Hasn't changed much even though gas has quadrupled in the last 20 years. If it was going up by the same factor you would expect to see premium cost a dollar more per gallon than regular...Patalrob wrote:Yep the gas companies love it when you burn the non regular gas. Probably costs them pennies per gallon if that to give it just a little more octane.
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I wonder if the percentage of cars that require premium fuel is increasing or decreasing.
"Old Guy's" SVT:
2004 CD Silver 3-door w/blue interior (one of 244 in that color scheme in 2004)
Build #879 of 1,978
Mods: JRSC+BBK; C-F-M Rear Engine Mount; FSWERKS Stealth Exhaust
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Build #879 of 1,978
Mods: JRSC+BBK; C-F-M Rear Engine Mount; FSWERKS Stealth Exhaust
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Require? I'd say decreasing simply due to the fact that cars are getting so much more sophisticated in the engine management.oldoutboardjim wrote:I wonder if the percentage of cars that require premium fuel is increasing or decreasing.
Look at the 2012 Focus, it's 12:1 compression but will run happily all day on 87 octane unlike our old SVTs that kick and scream if you even try to run midgrade.
On the other hand cars that can take advantage of the higher octane fuels are increasing in numbers for the same reason, at the auto show lots of the spec sheets showed different horsepower ratings depending on the fuel you put in the tank.
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