anyone using premium gas ?

[thejordan]

Originally Posted by mishka

for me the price difference is about $4 a tank at the current price ($3.70 for premium)

And what's your mpg difference?

[mishka]

Originally Posted by thejordan

And what's your mpg difference?

I have no idea. and i'm not sure how to accurately measure it because my driving habits vary.

[suss6052]

I have felt zero difference between 87 octane and 93 octane, although at this particular time during winter my mileage is much worse than it was when it was warmer, at least in terms of driving around town. It doesn't feel more powerful or faster, but then again I'm not constantly running it against the redline all the time or into the higher rev ranges.

Although if you were to wind it out and then slam on the brakes it tends to hang revs for a second or two after you stop, which is not good.

[mishka]

Originally Posted by suss6052

I have felt zero difference between 87 octane and 93 octane, although at this particular time during winter my mileage is much worse than it was when it was warmer, at least in terms of driving around town. It doesn't feel more powerful or faster, but then again I'm not constantly running it against the redline all the time or into the higher rev ranges.

Although if you were to wind it out and then slam on the brakes it tends to hang revs for a second or two after you stop, which is not good.

Yeah it does seem worse when it's colder , you're right. It's 20 degrees F here right now.. probly much colder in Michigan >;P
I haven't slammed on the brakes yet, and hope I never have to. I also have not seem it "hang revs" after stopping - yet - and hope I never do :)

[suss6052]

Originally Posted by mishka

Yeah it does seem worse when it's colder , you're right. It's 20 degrees F here right now.. probly much colder in Michigan >;P
I haven't slammed on the brakes yet, and hope I never have to. I also have not seem it "hang revs" after stopping - yet - and hope I never do :)

Most of the time if you stop even if you stop fairly abruptly it won't do that, only if you were really going and then suddenly stop, something I try not to do normally and the engine was wound up in lower gears it seemed to hold onto the engine speed longer than absolutely necessary.

I think I had finally managed to run into a use case that more people may see more often, which is a sign that they are typically abusing the vehicle most of the time as that had not happened before or since.

[mishka]

Originally Posted by suss6052

Most of the time if you stop even if you stop fairly abruptly it won't do that, only if you were really going and then suddenly stop, something I try not to do normally and the engine was wound up in lower gears it seemed to hold onto the engine speed longer than absolutely necessary.

I think I had finally managed to run into a use case that more people may see more often, which is a sign that they are typically abusing the vehicle most of the time as that had not happened before or since.

ok so you're saying that if one notices higher reving then normal after stopping, and they had not stopped abruptly, then they are abusing their car?

[Ranx0r0x]

dan50,

If you're getting stumbling with either 87 or 91 I'd say there's something wrong worth checking. I'm a new SE owner so don't know all the details of the engine operation of our vehicles.

In most new cars if the crank senses a difference in the amount of power from cylinder to cylinder the ECU changes operation. A common source of this problem is misfire. Plugs are a suspect and they are the cheapest to check and fix. A typical sign of plugs misfiring is stumbling at low RPM which smooths out at higher RPM.

Have you changed the plugs or wires recently? If so, did you switch from a colder to hotter or hotter to colder plug? Have you pulled the plugs to give them an eye?

Again, I'm a new owner of this vehicle/engine so I'm not up on its actual operation but this would be my first suspect.

[JasDmw]

Not sure if I'm allowed to post a link, but a Canadian consumer news program did a story on premim VS regular. To no ones real surprise, if you car doesn't need it (per the manufacturer), you are wasting your money. In fact, one very artsy lady driving a Honda Civic, who thought the environmental benefits outweighed the price was stunned to find the pollution form the exhaust is worse with premium! They had an expert put a brand new GM car on a dyno and measured all that could be measured. Essentially, the computers in our cars adjust to the fuel. In most cases there was no benefit and in some there were worse scenarios.

If posting the link is verboten; my apologies.

http://www.cbc.ca/marketplace/episod...mpfiction.html

[cobie56]

Originally Posted by JasDmw

Not sure if I'm allowed to post a link, but a Canadian consumer news program did a story on premim VS regular. To no ones real surprise, if you car doesn't need it (per the manufacturer), you are wasting your money. In fact, one very artsy lady driving a Honda Civic, who thought the environmental benefits outweighed the price was stunned to find the pollution form the exhaust is worse with premium! They had an expert put a brand new GM car on a dyno and measured all that could be measured. Essentially, the computers in our cars adjust to the fuel. In most cases there was no benefit and in some there were worse scenarios.

If posting the link is verboten; my apologies.

http://www.cbc.ca/marketplace/episod...mpfiction.html

the link does not work... even when i go to marketplace's home page.... the vid shows up but won't play... tried it on both a pc and a mac... oh, well.

[Ranx0r0x]

Originally Posted by JasDmw

...To no ones real surprise, if you car doesn't need it (per the manufacturer), you are wasting your money....

Fortunately for us the Focus owner's manual specifically states that higher octane fuel improves performance. Easiest way to do that isn't all that high tech. Just advance the timing until knock is sensed then retard it a bit. Higher octane resists detonation as it can handle higher pressure and heat.

In other words, with premium gas the combustion process can start earlier.

Knock is relatively easy to detect due to its almost universal sound spike at around 6400 Hertz.