Excursion problem
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Post Fiend
Joined: Sep 2005
Posts: 5,955
Likes: 9
From: Ohio
Excursion problem
My mileage is down and i cant figure out why. Last summer i was getting 480 per a tank which is roughly 11 to 12 average. For some reason, i don't know why, but im getting 380 per a tank. Today I filled up and now im getting 350. It seems to be dropping. Ive never changed the spark plugs before and it has a 103,500 miles on the orig ones. Also i can tell the IAC vavle is going because it likes to idle rough like 3 times a week. Could thops becausing the mileage drops? 350 on a 44 gallon tank is like 7.5 to 8 mpgs. What do you guys think is wrong?
Post Fiend
Joined: Oct 2002
Posts: 11,314
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No tuneup in 103K miles ?
with all due respect... the problem may not be with the Excursion
Need for a tuneup and basic REGULAR maintenance aside....
lift kit, tire weight, change in driving conditions, driving STYLE, front end alignment, carrying more weight, tire air pressure, air filter, fuel quality, fuel filter, etc.....
lot's of things...
with all due respect... the problem may not be with the Excursion
Need for a tuneup and basic REGULAR maintenance aside....
lift kit, tire weight, change in driving conditions, driving STYLE, front end alignment, carrying more weight, tire air pressure, air filter, fuel quality, fuel filter, etc.....
lot's of things...
Elder User
Joined: Apr 2004
Posts: 782
Likes: 0
From: Sweet Home Alabama
Check around the gas tank. Fuel leaks seldom show on ground as it evaporates quickly. Tune up stuff will not drop your mileage from 11 to 8 quickly, and tough to do that in a year even, it is 30%. My bronco had a small leak only when full or bad angles as the issue was on top. Little sealant and all was well.
Check brakes, one may be a little tight increasing resistance. Grease bearings, if they are worn or dry, it would increase resistance as well.
Air filter, tires would be maybe 10% decrease if dirty, or real low. 7-8 is towing 6-8K pounds mpg. Do you use the same gas? Try a tank of good stuff, or different stuff. I think BP/Amoco gold (premium) and Chevron Premium have best cleaners in their gas; get 1/2 prem and half regular. I get the best mileage with 6-10 gallons premium and rest regular only from Chevron or Amoco. Gives me about 88 octane overall with higher concentration of cleaning agents.
If that does not do it, maybe more serious like injectors or COPs.
good luck
Check brakes, one may be a little tight increasing resistance. Grease bearings, if they are worn or dry, it would increase resistance as well.
Air filter, tires would be maybe 10% decrease if dirty, or real low. 7-8 is towing 6-8K pounds mpg. Do you use the same gas? Try a tank of good stuff, or different stuff. I think BP/Amoco gold (premium) and Chevron Premium have best cleaners in their gas; get 1/2 prem and half regular. I get the best mileage with 6-10 gallons premium and rest regular only from Chevron or Amoco. Gives me about 88 octane overall with higher concentration of cleaning agents.
If that does not do it, maybe more serious like injectors or COPs.
good luck
Sit. Stay.
Joined: Oct 2001
Posts: 18,308
Likes: 20
From: Washington State
FWIW, it is against the law for gasoline companies to add different/more additives to the varying octanes. Chevron gas has the same amount of Techron in 87 as it does 91.
IEH, get new plugs, COPs & boots.
IEH, get new plugs, COPs & boots.
New User
Joined: Nov 2006
Posts: 11
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I averaged 11.2 miles per gallon year in, year out for about 90K miles. Switched to Schaeffer full synthetic oil and moved the average up to 11.4-11.5 mpg. Driving a stock 2001 V-10 4x4 4.30 LS, 140K miles
Mike
Mike
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Senior User
Joined: Nov 2006
Posts: 425
Likes: 1
From: Brooksdale, ON
I'd say it's your lift and new and bigger tires. you are actually going farther then you are reading on the odometer with the taller then stock tires.
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Sit. Stay.
Joined: Oct 2001
Posts: 18,308
Likes: 20
From: Washington State
Larger tires mess up the speedometer and hence, the odometer, reading. They also create more rolling resistance.
As suggested here and in the V10 forum, make sure your truck is 100%. Plugs, boots (definitely) & COP's (maybe) & a new fuel filter.
The rough idle may be due not so much from the IAC but from the worn plugs and possibly the fuel filter.
As suggested here and in the V10 forum, make sure your truck is 100%. Plugs, boots (definitely) & COP's (maybe) & a new fuel filter.
The rough idle may be due not so much from the IAC but from the worn plugs and possibly the fuel filter.
Senior User
Joined: Nov 2006
Posts: 425
Likes: 1
From: Brooksdale, ON
Here are some numbers for you. In 1 mile a 31" tire turns 653 times. A 33" tire turns 592 times. That alone is close to the 10% loss in milage. A 31"tire has a circumference of 97" and a 33" tire has one of 103" so for every turn of the tire you are short 6" on your Odometer. Now what also happens is that as tire wear happens the size of your tire gets smaller so that number is never acutarte once you turn a mile down the road, hence the reasoning behind inaccurate speedos.
Elder User
Joined: Mar 2005
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Originally Posted by Monsta
The rough idle may be due not so much from the IAC but from the worn plugs and possibly the fuel filter.
Elder User
Joined: Apr 2004
Posts: 782
Likes: 0
From: Sweet Home Alabama
Monsta-i have heard and read conflicting reports on that, so maybe my X is just more efficient with 88 octane. I have messed around alot with it and as geeky as it may be, I kept a log since mile 54 on the odometer and it will do .25-.5 better when I increase octane to 88 although not with midgrade. I always run 100 gallons or more during experiments and take the mpg over 2-3 tanks. I thought cleaning agents helped, either way it makes me feel better.
Hybrid-I just assumed you knew the lift consequences. My speedo was off 9.5% with the new 35s and now it is off about 8% due to wear on tires as sewerat said. You can use milemarkers on the interstate to measure actual vs odometer (use at least 10 miles) or use a GPS which will show actual speed to find difference.
Hybrid-I just assumed you knew the lift consequences. My speedo was off 9.5% with the new 35s and now it is off about 8% due to wear on tires as sewerat said. You can use milemarkers on the interstate to measure actual vs odometer (use at least 10 miles) or use a GPS which will show actual speed to find difference.