nvflash74

A test with 92 Octane gas yielded 46.0 MPG at 55MPH and 36.3 MPG at 70MPH. So it's about a wash, basically 50 cents more per gallon than 88 octane gives 15% better milage. However I'm sure I get more Horse Power, so I'll just run the higher octane fuel and avoid too much timing coming out. I ordered a K&N cold air intake and I'll update these numbers once I install that to see if I pickup any fuel mileage.

Say, thanks for the info. So I did some data logging after a few tanks of 88 octane gas. I also used an SCT x4 to reset the KAM. I ran out I-65 about 70 miles or so just to let the computer relearn some of the fuel trims and shift points. Then I set the cruise control to 55mph and ran out about 60 miles with some hills. Result: 39.9 MPG. So the trip back from Charlotte of about 80 miles I pretty much must have been doing 55mph most of the way. Mom drove me up to buy the car because I was not trading in my old car, and I remember when we got to the one spot on US74 that is 70MPH she ran off and left me, I didn't notice she was gone, but when I did I sped up to 70. Likely I just did 5 or 10 miles at 70MPH and most of the trip I did at 55 with very few red lights and most of it expressway. I'm going to say the gas that was in the car was likely 91 or 93 octane. I don't know, they filled it up when I bought it. I was thinking I did some testing at 55mph a few times, but I don't think I ever did it on higher octane gas and I never reset the KAM before. Anyway, I think I'll run a few tanks of 93 Octane through it, set the tires to the max tire pressure on the side of the tire. Run out 100 miles on I-65 at 55mph and log that, then run back at 70mph and see if that 500RPM really makes the difference between 34mpg and 40mpg HWY. One thing tho, with the cruise set at 72mph even on a pretty steep hill, all I got was about 1PSI of boost. If I really got in the gas I would peek about 16.5PSI of boost on both a VAC/BOOST GAGE and my SCT x4 in gage mode. So other than giving more horse power, the turbo does nothing for gas milage that I can tell. At 55mph even up a grade it stayed in 6 gear on the CVT and I never saw any boost. Sure more HP is fan when you want to slam the gas, it's just not going to do anything for milage in cruise control mode unless you are really pulling some mountains or towing a trailer. Also, Ford is really vague about the octane rating of the fuel you should use. Basically if you want the full 245HP you need to use at least 91 octane fuel all the time. 87 just takes timing out because of the spark knock when you hit a boost condition. Right now I can get 88 octane fuel 5 cents cheaper than regular 87, but I assume it is E15, and that is all Ford says the car is rated for, not to use e85. So are these cars e85 safe with the right tune or are the seals in the fuel system not flex fuel safe?

So in 2019 I bought a used 2016 Fusion SE 2.0L EconoBoost from a lot in Charlotte,NC. It had 2,500 miles on it and that was amazing for the age of the car, whoever had it just dod not drive it at all. So on the 90 mile drive down from Charlotte to Fayetteville I got 39.8 MPG and I could hear the turbo making the slight whistling sound I am accustomed to from years of driving big rigs. I never got near that milage again, best I could do on long hwy trips was about 36 MPG and slowly I've lost fuel economy in city and on hwy. With about 75k now on HWY I get about 32 MPG and in the city I get about 22 MPG. I have a real smooth driving style and always get better than the EPA estimated fuel milage out of every car I drive. I'm still using the factory break pads on this fusion and they still have a little life in them at 77k, that's how smooth I break. So I figure the waste gate on the turbo is opening when it should not be, I got a vacuum and boots gage and hooked it to one of the two vacuum lines that come from the intake across the top front of the engine compartment. I think it is hooked up proper. When I gun it boost builds to around 18 pounds before the waste gate opens, but at 70 MPH it's not building any boost at 2200-2300 RPM. Once in a while it will build up about 5 pounds between 55-75 MPH and hold there, but only once in a while. So shouldn't it be building boost at hwy speeds? If I gave it more than 1/2 throttle I get boost until I let out or over pressure opens the waste gate, but not really any boost what so ever at less than 1/2 throttle. I almost never use more than 1/4 throttle so my turbo really isn't doing anything, right? I have never had any check engine codes on this car, so I'm just not sure what is going wrong? Should I look at the boost sensor in the charge pipe?