Originally Posted by Dgc333
Actually on pg 354 it talks about some parts of the country regular gas is 85 octane and that the car will run better on premium than 85.
It does not say it will run better with premium than the 87 octane available to most of us.
This is the third time in this thread i have mentioned this.
Just because you've mentioned it 3 times doesn't mean you're correct.
Focus Owner's Guide Two Thousand & Twelve
, Page 354
, Para 4
"Your vehicle is designed to use "Regular" unleaded gasoline with a pump (R+M)/2 octane rating of 87. Some stations offer fuels posted as "Regular" with octane ratings below 87, particularly in high altitude areas. Fuels with octane levels below 87 are not recommended. Premium fuels will provide improved performance."
Now I'm not an English major but the last sentence doesn't have a dependent clause linking it to the previous sentences, nor does it have any conjoining words. This paragraph is providing us with 4 key pieces of information 1) You vehicle is designed to run on 87. 2) Some stations offer fuels with an octane rating below 87. 3) Running fuel with octane ratings below 87 is not recommended. 4) Running premium will improve performance. 1 and 4 are a bit conflicting but I think I covered my theory on that is my previous post. (Provided below)
Listen, I'm not saying your wrong, because I have no actual proof and the last sentence is a bit ambiguous however, from my interpretation of the manual it states that "Premium fuel will improve performance". It doesn't say ", therefor running premium fuel in areas where (R+M)/2 87 is not available will improve performance. I said right in my post "One day I'll figure it out" because at this time all I have is my interpretation of the manual.
My original post for your convenience.
Originally Posted by JSR84
The manual also states that running premium will result in increase performance.
Most modern engines are tuned with high and low ignition tables. Which if true for the Focus, it would make sense why they recommend regular but also state that premium will increase performance(Page 354 "Octane recommendations" last sentence in the owners manual.). One day I'll hook it up to my Dash Hawk and try and figure it out.
My G8's had high and low octane tables and running on the low octane table the car made around 8HP less than the high octane table (Stock). It switched to the low octane table when it detected a predetermined knock count withing a set time frame. It was kind of a PITA when trying to tune the thing because it was pretty sensitive and switch over when it wasn't needed. I ended up just cloning the high table on to the low since I wasn't planning on running anything less than 94.
God I miss that car.