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00' F-150 xlt Super Cab 4x4 296,500 on the clock.
I had some issues with the truck a few a months ago (see attached
miss-fire count on cylinders) I replaced all coils with MC and sp479 plugs.
All was good up in till about a week ago I noticed my fuel mileage had
gone to hell, I mean 1/4 tank in less than 50 miles!
It runs alright while driving, maybe a little on the sluggish side but not like
its flooding out from fuel. Is it possible for injector (s) to leak or put out
to much fuel? No codes, or miss-fires.
Any parts replaced on this truck has and always
will be motor-craft.
50 in 1/4 tank isnt that bad for some around town. 1/4 tank is too imprecise to judge.
I mapped out the miles I drove since fill up and since my odometer works
once in a while 32 miles on Saturday.
Tires 295-70-17
Gears 410's
Engine 5.4
Dyno Tuned and have it checked and adjusted every spring and fall due to
the high temps in Arizona, the AIT's get really high here in summer.
Fuel trims spot on as your can see in my original post above that was
about 3 months ago.
I think I figured out what happened, working out of town and pretty sure
I got a bad tank of gas in Buckeye. I burned it down to almost a 1/4 of
a tank today. So will refill tomorrow and report back.
Thanks!
Speaking for my 98, it seems at around 90* F and beyond, it reacts terribly. Everything takes a hit for some reason. - Fuel ,braking, power. I don't think it's my imagination....it's the heat!
With the miles you have on the engine (I'm closing on 350,000 mile as well) and that Arizona climate you take what you can get from the truck. All you can do is provide good maintenance...all that's worth doing IMO.
Good maintenance, civilized driving and 4 fresh 02 sensors every 100,000 miles will get the best mileage these trucks can do.
Also, -When a custom tuned vehicle begins to act drastically different in way of fueling, power. One of the very first things to do is check the tune. You do that by defaulting back to the original tune for awhile to confirm. Since custom tunes aren't always that stable.
Had a brand new 4x4 Isuzu Trooper in 1995. Took it on a road trip to Colorado that winter. Started out 18 and a half miles to the gallon on the interstate. By the time we got to West Texas north of Amarillo was getting 12 miles to the gallon when I stop for gas. I was worried something wrong. Why,? Well when I got out to pump gas the wind like to knock me over we were driving into a 40 mile an hour headwind. Bad part was it was hard to estimate fuel range with that kind of variability.
In Colorado up in the mountains I got 21 plus miles to the gallon. Such is the life of a boxy non aerodynamic vehicle. Repeated that trip several times and that vehicle and it was always the same 18 miles per gallon down at sea level 21 to 22 up in the mountains. So with a working vehicle in top shape my miles per gallon varied from 12 to 22.
Point is a few miles on a fraction of a tank of gas don't tell you much
Speaking for my 98, it seems at around 90* F and beyond, it reacts terribly. Everything takes a hit for some reason. - Fuel ,braking, power. I don't think it's my imagination....it's the heat!
With the miles you have on the engine (I'm closing on 350,000 mile as well) and that Arizona climate you take what you can get from the truck. All you can do is provide good maintenance...all that's worth doing IMO.
Good maintenance, civilized driving and 4 fresh 02 sensors every 100,000 miles will get the best mileage these trucks can do.
Also, -When a custom tuned vehicle begins to act drastically different in way of fueling, power. One of the very first things to do is check the tune. You do that by defaulting back to the original tune for awhile to confirm. Since custom tunes aren't always that stable.
Summer time here, 118* in the shade 5:00 p.m. rush hour traffic AIT's
in the upper 160's! But I mostly avoid that since work construction and
home by 2:00 p.m.
I take care of this truck, never go over 4k oil change, plugs every 15-20k.
I can't imagine driving this truck with out the tune! I will pull the chip this
weekend and and drive it for a week and report back.
Thanks!
A few months back, I was driving from Tampa to the Pensacola with my xlt, about a 6 hour drive. I noticed a big increase in fuel use almost as soon as I started. I musta put hundreds of dollars of fuel in on the way up. I was freaking out. Just before I finally arrived I got a check engine light. Dropped the code and my downstream O2 sensor was bad. Changed it and fuel usage was back to normal after that. Took a good couple hundred miles to get that CEL though.
A few months back, I was driving from Tampa to the Pensacola with my xlt, about a 6 hour drive. I noticed a big increase in fuel use almost as soon as I started. I musta put hundreds of dollars of fuel in on the way up. I was freaking out. Just before I finally arrived I got a check engine light. Dropped the code and my downstream O2 sensor was bad. Changed it and fuel usage was back to normal after that. Took a good couple hundred miles to get that CEL though.
You got me thinking, I checked my log and found that the last time I
replaced 02's was about 78,000 miles ago. Come to think of it when I
bought this truck it had 130,000 miles on it and never had a Cel, only
when I forgot to plug some thing back in or didn't plug in all the way.
I had problems with the cops though, friggin thing (s) will miss but
never enough to throw a cel and tell you which one it is!
About due to replace 02's anyway so will order a set M.C.'s
Thank You
A few months back, I was driving from Tampa to the Pensacola with my xlt, about a 6 hour drive. I noticed a big increase in fuel use almost as soon as I started. I musta put hundreds of dollars of fuel in on the way up. I was freaking out. Just before I finally arrived I got a check engine light. Dropped the code and my downstream O2 sensor was bad. Changed it and fuel usage was back to normal after that. Took a good couple hundred miles to get that CEL though.
Because of the way they are monitored and tested throughout the drivecyle it's sort of a drawn out process. The sensor won't show bad until it fails 3 times consecutively and that could take awhile. For this reason, they SHOULD be replaced at 100,000 miles. It's their lifespan and that's fairly accurate.
Say you were to get two fails and then a pass during monitor testing. You would be dragging out the inevitable but during this time putting up with very bad economy. It will also run like *** lol. You'll never experience the problem normally, if you swap them ALL out every 100k. Have to swap all 4 out though, not just two if you want that truck running perfectly...or as good as it can. Kind of like a advanced maintenance regimen to follow.
Running with bad O2 sensors transforms the vehicle into slow poor running slug. Your always on fuel, always sucking it. They are toast when get CEL, but are bad way before that occurs. Reason for the 100k regimen.
Using a lot of fuel
