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Posted (edited)

I don't want to speak too soon but I only just got my truck 2 weeks ago and I'm getting 15.5 to 16.0mpg in 100% city driving according to the display. (CCSB, 5.3 v8, 4x4, 3.42 gears) Hopefully it continues. My 04 and 09 F150 4x4 crew cabs with 5.4 v8 only got 12 to 13mpg driving the same exact roads. My other family members with F150 3.5 ecoboost get in the 14's mpgs driving the same city roads.

Edited by stevev
Posted

Why are people running premium? Higher octane is only to prevent detonation in higher compression engines and doesn't contain any more chemical energy than regular. Doesn't seem to be worth the 30-50 cents more.

Most if not all of the 5.3l engines will have detonation on 87 octane fuel. There is some on mine running premium fuel and even see it on e-85 ocassionally. If you have some way to monitor this on your truck you should check it out.

Posted

I've got a bit over 8,000 on mine now. A 5.3 with 3:42 rears. I run the same route to work every day since day one. Don't really drive it much on the weekends. Just about half of the 73 miles a day is traffic and red lights, the other half is cruisin' at 70-74 mph on the pike. I've averaged just shy of 20mpg for the past 6,000 mile. I always do the 400 mile average on the DIC. I'll have to get a pic.

 

I have tried premium a few times and every time, I get just about an extra 1 mpg. One other thing I've noticed is my engine seems to really like warm/hot weather. Every time it's cooled down, (I'm talking high 60's to low 70's) my mpg struggles.

 

I bought the truck in March which is the tail end of our winters. Thinking because of it being new it didn't do very well with mileage. Cold weather always plays a part too. It didn't do much better than 18 on its best days. As the weather got warmer the mpg steadily rose, to what it is now,and it's been rock solid with those numbers. The DIC and my own calcs are pretty much right on. Same station, same gas (Sunoco), and actually the same pump too! :)

 

If I ever get the chance,I'd like to take it on a long highway trip to see what kind of numbers I get.

Posted

Most if not all of the 5.3l engines will have detonation on 87 octane fuel. There is some on mine running premium fuel and even see it on e-85 ocassionally. If you have some way to monitor this on your truck you should check it out.

 

I can't find much about that, any links?

Posted

 

I can't find much about that, any links?

 

I can't find much either.

I don't know for certain,but I'm thinking that would be more so on the older 5.3's.

Posted

 

I can't find much about that, any links?

Can't copy links on the phone but look up 5.3l KR while data logging. It is in the engine section

Posted

I notice when I first bought my truck it ran better on E85 or 93 gas. A few months ago the tuners where seeing KR on 87 gas. I guess it wouldn't hurt the 5.3s to run 87 gas but your not getting the performance if its hitting KR a lot. I run E85 it cheap and easy to get for me, the performance on it is noticeable.

Posted

I put in 93 today. After intake and exhaust mpgs went up about 5 miles. However timing had to be pulled because it seems that torque on the low end was lost. So I think if I'm doing city commuting I'll stick to 87, but if I'm going on a road trip where I'm not doing so much acceleration, I'll stick to 93 for the commute.

Posted (edited)

Has anyone brought up the KR issues with a dealer?

I personally did not. I am sure they saw it and let it go so I figured why bother; not sure how the couldn't have. WOT they are good, it is just under light throttle and cruising situations. The sensors do what they are supposed to so it is "safe" but it is greatly reduced with higher octane fuel. I think they made the timing so aggressive in these areas to pull all they could from the motor MPG and power wise.

Edited by CAtaylor
Posted

What the hell?!

Don't let it fool you, that's easy to do, reset your mpg on trip a and coast down a hill. Then read your average

 

 

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