03 5.4L- Many Issues, any help appreciated.
03-02-2009, 09:53 PM
#1
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03 5.4L- Many Issues, any help appreciated.
I have an 03 half ton with a 5.4, with only 51000 miles. Its an Fx4 ex cab short bed.
Ever since i got it, this thing got terrible mileage. With the stock tires, stock everything, i got about 13 in the city and 15 on the highway.
A while ago, i cranked up the torsion bars to level it out, put on a Gibson cat back single and a true flow intake, as well as a set of 285/70R17 BFG mud terrain KM-2s on the stock FX4 rims.
After that, i cant get above 10-11 corrected in the city, and about 13 on the highway. My foot is not that heavy at all, i dont drive like a mainiac.
Anyways, i change the oil every 3K, it has also had a fuel filter change, tranny fluid change, rear diff change, tranny filter, and O2 sensors which showed bad on the computer. I also put through some of that injector cleaner stuff to no avail.
After all this, i still get the same mileage. Whats the deal? Im gonna clean the MAF sensor and see what that does. After looking everywhere for the distributer, i realized the 5.4L has coil over plug setup. What can i do to check my electrical system to make sure its kosher? The computer shows nothing wrong.
Thanks for the help
-Kip
Ever since i got it, this thing got terrible mileage. With the stock tires, stock everything, i got about 13 in the city and 15 on the highway.
A while ago, i cranked up the torsion bars to level it out, put on a Gibson cat back single and a true flow intake, as well as a set of 285/70R17 BFG mud terrain KM-2s on the stock FX4 rims.
After that, i cant get above 10-11 corrected in the city, and about 13 on the highway. My foot is not that heavy at all, i dont drive like a mainiac.
Anyways, i change the oil every 3K, it has also had a fuel filter change, tranny fluid change, rear diff change, tranny filter, and O2 sensors which showed bad on the computer. I also put through some of that injector cleaner stuff to no avail.
After all this, i still get the same mileage. Whats the deal? Im gonna clean the MAF sensor and see what that does. After looking everywhere for the distributer, i realized the 5.4L has coil over plug setup. What can i do to check my electrical system to make sure its kosher? The computer shows nothing wrong.
Thanks for the help
-Kip
03-03-2009, 12:06 AM
#3
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Torsion bars? Didn't know we had them...you sure? As far as the mileage goes that is about right...we just have to deal with it...the bigger tires can affect your mileage...rolling resistance higher, increased drag on the drivetrain... maybe throw off your computer, RPMS, reverse all the changes & check again...you might have inadvertantly made it worse
03-03-2009, 01:30 AM
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Yeah, it has torsion bars. Not sure which year has it and which doesnt.
I love the pickup dont get me wrong, and am a die hard ford fan. I have taken this thing through so much stuff im amazed at how well it holds up.
It doesnt seem to run great either. I have starting issues with it.
My buddies 98 k1500 350 is faster. The 350 is a good motor, but his is all stock, and mine claims more HP and TQ. He has similar tires, and can roast them to peices, and i have to work to get mine spinning.
It will sort of stutter every time i start it, and then get going. It actually would not start on me one time, till i gave it gas, then it fired up.
I love the pickup dont get me wrong, and am a die hard ford fan. I have taken this thing through so much stuff im amazed at how well it holds up.
It doesnt seem to run great either. I have starting issues with it.
My buddies 98 k1500 350 is faster. The 350 is a good motor, but his is all stock, and mine claims more HP and TQ. He has similar tires, and can roast them to peices, and i have to work to get mine spinning.
It will sort of stutter every time i start it, and then get going. It actually would not start on me one time, till i gave it gas, then it fired up.
03-03-2009, 07:36 AM
#5
OVERTHINKER
2 recommendations that I do myself, first don't buy gas with ethanol and second get a tuner so you can run 91/93 gas.
A little info about fuel; from Thanksgiving to Easter we get winter mix for emissions control and it burns faster. From Easter to Thanksgiving we get summer mix which burns a little slower. Add ethanol to the mix and everything burns faster.
Back to the tuner and its value at 91/93 octane; 91/93 burns slower than lower octane so you get more millage out of a gallon of fuel. Don't go out and just start putting 91/93 in your truck without a tune because without the tune your timing is not compatible with the higher octane burn.
I got 13-14 mpg in my 5.4 until going to a tuner and now I get 16 mpg as long as I keep my foot out of it.
Don't take my word on this alone. Do your own research.
A little info about fuel; from Thanksgiving to Easter we get winter mix for emissions control and it burns faster. From Easter to Thanksgiving we get summer mix which burns a little slower. Add ethanol to the mix and everything burns faster.
Back to the tuner and its value at 91/93 octane; 91/93 burns slower than lower octane so you get more millage out of a gallon of fuel. Don't go out and just start putting 91/93 in your truck without a tune because without the tune your timing is not compatible with the higher octane burn.
I got 13-14 mpg in my 5.4 until going to a tuner and now I get 16 mpg as long as I keep my foot out of it.
Don't take my word on this alone. Do your own research.
03-03-2009, 07:05 PM
#6
Senior Member
5.4 Mileage - Live with it
Yup, it sounds like you're getting around what everyone is getting. I just traded my '00 F-250 SD 4x4 with over 100K miles and it got 11-12 mpg consistently--didn't matter whether it was around town, on the X-way at 65, or towing a 16' landscape trailer loaded with equip. 'Course, the truck had the 4.10 LS diff with the tow package, so I always considered myself lucky to average better than 10 mpg....
As for stepping up to the higher octane, I doubt if it will net you that much more mileage to justify the cost. While your computer M-A-Y give you a bit more advance because you won't experience any pre-detonation, you'd have to make some seriously expensive internal mods to increase the compression ratio to 10.5 - 11.0 to see a major increase in efficiency.
Bubba
As for stepping up to the higher octane, I doubt if it will net you that much more mileage to justify the cost. While your computer M-A-Y give you a bit more advance because you won't experience any pre-detonation, you'd have to make some seriously expensive internal mods to increase the compression ratio to 10.5 - 11.0 to see a major increase in efficiency.
Bubba
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03-07-2009, 09:17 PM
#8
Senior Member
I had a 2oo3 with a 4.6 and my mph was low also . I added the exhaust and the programmer my mph went up a little.
I just bought a 2008 5.4 put 35" tires with CAI, Exhaust and Programmer MPH is 13 -15 around town and 18-20 freeway my 2003 2wd got worse than my new lifted 4x4
as far as your shudder on take off or hard start ? was it
Check your coils, spark plug boots under the coils for cracks, ck for a bad vac leak any where.
On my new truck when they lifted the truck they damaged the right hub which gave me a vac leak at the right hub. that vacum came from the vac hose to the brk booster, my mph went to 9 -10 mph
but after the hub was replace the mph went back up.
The truck was running too lean!
I just bought a 2008 5.4 put 35" tires with CAI, Exhaust and Programmer MPH is 13 -15 around town and 18-20 freeway my 2003 2wd got worse than my new lifted 4x4
as far as your shudder on take off or hard start ? was it
Check your coils, spark plug boots under the coils for cracks, ck for a bad vac leak any where.
On my new truck when they lifted the truck they damaged the right hub which gave me a vac leak at the right hub. that vacum came from the vac hose to the brk booster, my mph went to 9 -10 mph
but after the hub was replace the mph went back up.
The truck was running too lean!