syntheticreality

I am new to the forums here. I own a 2004 4.6L supercab 2WD. I am noticing a gas mileage drop that may be due to the winter, but seems worse than usual.

My mods are as follows:
-Custom exhaust with side exit. Both tips come out in front of the passenger rear wheel. It has a magnaflow muffler and 2.5 inch pipes.
-K&N Air filter
-Diablosport predator Tuner

On my recent trip from NY to FL, I was had two motorcycles in the bed weighing around 450lb each and some luggage in the back seats. I got 16-17 MPG on the highway. On the return trip, my gas mileage on the highway dropped to 15.6, then 14.9, then 14.8. I recall that I used to get over 18 on the highway and typically 15ish in the city.

Now for the questions:
1. What mods can I do to further improve my MPGs?
2. Am I in need of some sort of tuneup?
3. I am considering putting 18 inch rims and slightly bigger tires and pissubly even a leveling kit. How much will this hurt my gas mileage?
4. Does the 5.4 get better mpg's than the 4.6?

Thanks in advance and sorry for any repeat questions. I tried to use the search feature to answer these, but I really didn't find adequate answers.

CrashTECH

Read my post here: https://www.f150forum.com/f4/mileage...x3/#post359873

1. There are a few, UDP, eFans, Gears. However modding for better MPG alone is a bad idea. It will take a LONG time to re-coup the costs. UPD and eFans (if you build your own kit) will take 25-30k miles to earn back at best. This is a break even point.

2. Not likely. If you have followed your normal maintenance anyway.

3. Depends. Leveling kit may or may not affect it by more than .5 mpg or so. Wheels and tires is too wide to know. Depends on tire height, wheel weight, etc.

4. No. At least as a general rule not. They are probably so close it doesn't much matter although the theory is that the 4.6 would be better. I haven't seen much evidence that it is better by a significant amount.

atvrider93

I'm not sure what the conditions were for each but weather will affect mileage and aggressiveness and traffic with greatly affect mileage. e fans and UD pullys would help a little but not much difference.

syntheticreality

will efans and UD pulleys give me much more power? Are there any downsides to those?

CrashTECH

They won't give you power, so much as free it up from what is already there. Belt driven accessories consume energy from the motor so you have less available for the wheels.

a UDP will spin the accessories slower, reducing the load on the motor. This is fine normally but if you tow a lot (or really heavy things) OR you have a big stereo system with big amps I wouldn't do it. It will reduce the output of your alternator which will be an issue in some cases.

The only real down sides to the eFans (the fan is mechanical belt driven) is that it adds some complexity (which isn't a big deal, most vehicles have electric fans). It could also be seen to be more prone to having issues where the mechanical fan just spins when the engine does. I think though that the fans can keep up just fine for all but the most brutal conditions.

HankBob

I get 9.5 mpg on my truck (04 5.4L f150) and it used to get better gas milage, though it was still only 10-12mpg it still saved me a lot of money. Ever since I got it back from the shop it dropped to 9.5. The locked the cam phasers and did a few other things. My spark plugs were already brand new so they didn't replace them but I don't know why it is so bad. Im on 33x10 in tires so they aren't very big and the truck isn't lifted or anything either. I do have a steel front bumper but even before the shop I had it and the mpg were better. Any advice?

laterongc

put on stock wheels/tires, stock bumper, and do basic tune up (TB MAF clean, TB relearn, etc).

needsmoarturbo

Didn't you just make a threat about your transmission being shot? Maybe that's part of the issue?
And you said you warm it up? Warming the engine up gets you zero mpg for however long it's idling which really drags down your average....