Need some suggestions to increase fuel economy

[Jay87LX]

Hi Guys,
I have been away for a minute, I bought a 2012 Harley Ultra Limited and have been on the Harley forums checking things out.
Anyways, I have a '99 5.4 with 99K on the clock and have been averaging 8MPG, yes 8!!!
I am trailering the bike to Myrtle Beach in May and want to at least change the plugs as I think they are originals and may be a major cause of the terrible fuel economy. I know expy's aren't the best on gas but I think 8 is ridiculous.
Any suggestions on plug types and anything else I should do to help out the MPG's?
Part of me wants to leave well enough alone as I dont want to be in the middle of I95 in New Jersey at 3am and have a plug blow out 700 miles from home but I know they NEED to be done.
Also where is the link on how to do the plugs on the '99 5.4. Any other suggestions would be appreciated- Jay

 

[Knautical2001]

K&N air filter and exhaust helps. ..... or just buy a $500 Honda Civic. LOL

 

[Knautical2001]

Myrtle Beach is a drive from Mass.... Doing the plugs should help as well.

 

[SkyJumper]

Jay, there is alot of small things you can do to improve mileage without being told to buy this and that and fork over a pretty amount of money.

1) New plugs (Motorcraft Platinum) and wires.
2) Fuel Filter
3) Fuel treatment (SeaFoam) or injector cleaner at your next fill up.
4) Tire Pressures
5) Air Filter
6) Clean out the throttle body
7) Drive belt
8) Go thru all the vacuum lines and make sure they are serviceable
9) Battery maintenance and grounds.

If you want to upgrade then possibly a CAI, and exhaust upgrade and handheld tuner. But like I said, that is money and not routine maintenance.

 

[GAINMOB]

exhaust, programmer, efan....just to start

 

[GAINMOB]

intake

 

[ExpeditionDrew]

how do you clean the intake.....

 

[GAINMOB]

i'll have to get in the book...cant remember if its not recommended to use injector cleaner on my truck per manual or if im thinking of my wife's 2011 altima

 

[walnuts4x4]

I'll agree with the maintenance first.... then a CIA and free flowing exhaust... and last a programmer.... just FYI... my 99 5.4 with 11" lift and 37s is getting 11-12 city and 13-14 highway... with stock 3.73 gears... other setup in my sig

 

[bnegaard]

I know this is a little bit old but have you checked your mileage manually or are you going by the computer? Also do you have any mods on the engine or oversized tires? I am not sure how you could get a drop of ~40% (most are getting 13-14) unless something is seriously wrong. That would result in a warning light and a code. Before you modify the engine I would sort it out and figure out if you have any problems. Its a bear to sort out everything after a mod when it was messed up before you started making changes. As for mileage mods-there just are not that many that are cost effective. You generally can get more power at the high end which feels good. but my experience has been that few mods pay for themselves-your are generally trading one issue for another. Power on the other hand is easier. Contrary to popular opinion OEM equipment is pretty good and dependable.

 

[CARO'S98EB]

there are 2 ways to increase fuel econ- reduce load and increase efficiency.

load is aerodynamics and rolling resistance mainly- narrow street tires and smooth airflow[lowering, air dams...] will lower the load also somthing like a electric fan may help, but it is then something else to pay for and maintain.

efficiency is harder- slicker oil, better fuel good plugs unrestricted intake good exhaust and sometimes a tuner can help.

IF you want good mileage get a cheap econobox to drive when you dont need the Expy.