12 mpg is three something wrong
Junior User
Joined: Jun 2005
Posts: 70
Likes: 0
I'd say there is definitely something wrong with your truck. I have a bone stock 98 F150 Offroad w/the 4.6 and I have consistantly avg'ed 17 mpg since new. It has the 3.55 rear and 125K miles. Normal driving is about 1/2 highway and 1/2 red light to red light.
Don't know what it is thats not set right on your truck but I'd guess it's running too rich (do you see black smoke?) and/or the timing could be way off.
Good luck
Don't know what it is thats not set right on your truck but I'd guess it's running too rich (do you see black smoke?) and/or the timing could be way off.
Good luck
Freshman User
Joined: Oct 2006
Posts: 43
Likes: 0
From: Davie Fl
Originally Posted by Volfandt
I'd say there is definitely something wrong with your truck. I have a bone stock 98 F150 Offroad w/the 4.6 and I have consistantly avg'ed 17 mpg since new. It has the 3.55 rear and 125K miles. Normal driving is about 1/2 highway and 1/2 red light to red light.
Don't know what it is thats not set right on your truck but I'd guess it's running too rich (do you see black smoke?) and/or the timing could be way off.
Good luck
Don't know what it is thats not set right on your truck but I'd guess it's running too rich (do you see black smoke?) and/or the timing could be way off.
Good luck
Senior User
Joined: Jan 2008
Posts: 121
Likes: 0
Originally Posted by BLackFenton
I agreed with Volfandt you sound like your running to rich and off timed
Come on guys.... TIMING???????????? I know you guys arent trying to tell hime to check his distributor timing.
What kinda gas are you using? If its oxgenated 10% ethanol. You will be seeing a mile or 2 less per gallon. If your plugs are at 60k try pulling out a couple and checking out how worn they are. Look at the lights and coast as much as possible. Dont let the engine idle other then for 20 or 30 seconds after you start it up in the morning. take out all unecessary junk. Dont run the a/c compressor unless you totally need defrost. After running your truck crawl underneath and using a temperature sensor.. like a handheld type with laser pointer, check your before and after temperatures on you cats. They may be plugging up. I cant remember what year you said it was, but lets just say its a 2000 model year. With 60k on the clock that truck was not drove very much like only 7k miles a year. Chances are that it was short trips and thats not the best conditions for cats.
try keeping it waxed up and clean. My grandad swears that will get you half a mile to the gallon. Try a drop in a/f i wouldnt pony up to a full cai. I bought one 5 years ago and its noisy... didnt notice my of a gain. Try cleaning out your MAF. Make sure that you are running 5w30 oil, not 15w40.
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Freshman User
Joined: Feb 2008
Posts: 37
Likes: 0
From: maryland
ight guys m using 87 octane i just cleaned the maf and used throttle body cleaner and through some BG fuel sysetem cleaner additive in the tank, and the last person to change the oil was the dealer at 60,000 miles and it has 60,700 so i guess they used 5w30 next change ill be going with 5w30 mobil 1, the air filter was also like newin the morning the most it sittis idling is 5 min befor i go to school if that , and no black smoke even when i used the TB cleaner it balrely smoked,
Junior User
Joined: Jan 2005
Posts: 57
Likes: 0
From: Yardley, PA
Take your truck to a mechanic or dealer and have it scanned for codes. My '97 F250 LD 5.4 was getting poor mileage with no indication of a fault. A scan discovered a faulty O2 sensor, it was replaced and the dealer reprogrammed the ECU. Great mileage since the repair.
Senior User
Joined: Jan 2008
Posts: 174
Likes: 0
From: Western Pennsylvania
When I fist bought my truck a few months ago, used that is, it was getting 12mpg. Since I have had it, I have put new plugs and wires in it, new fuel filter and air cleaner, a performace exhaust system and changed the oil and filter to manufactures specifications. the truck not only has more power but i currently getting about 17mpg. This a notiable difference. i am happy and my truck is happy with 
Bowdog
Bowdog
Senior User
Joined: Jan 2008
Posts: 121
Likes: 0
Originally Posted by bluealtered
I find the before and after temps on the cats interesting, does anybody have a rule of thumb for what they should be as to good/bad? ... O ... and my spellings this way cuse i'm lazy. blue
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Post Fiend
Joined: Jan 2004
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From: Elkhart IN
You don't have to take it to a dealer to pull codes, autozone or the like will do it for free. I would start there though. How old are the o2 sensors? How are you calculating your mileage? Do you still have stock tires?
I know it may be expensive, but running some good unleaded race fuel through an engine will help clean it up some. I run 110 octane in my four wheelers, and it keeps the heads, pistons, and pipe a light gray color it burns so clean.
I know it may be expensive, but running some good unleaded race fuel through an engine will help clean it up some. I run 110 octane in my four wheelers, and it keeps the heads, pistons, and pipe a light gray color it burns so clean.
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