Ok, I'll let you know now, this post will be alil long but i appreaciate anyones help.

I have an 02 f150 4.2L SuperCab. Lately it seems that my MPG has gone down drastically. My tires are almost new and fully inflated, clean air filter, and no unnecessary weight in the truck. I think it may need new spark plugs cuz it idles really rough in drive and reverse but wht would yall think?

I'm also abt to add a few engine mods to get some more grunt outta it, I was gonna get an engine swap but thats too much trouble. I plan on dropping in a throttlebody, k&n CAI, a JET performance module, new headers, and flowmaster 40's dual rear exit. But what I am wondering about the mods is the exhaust. I found a guy on youtube w/a 40 series, no cats, and stock headers. Here's the link. http://www.youtube.com/watch?v=Hb9IDN5JzjQ

Would aftermarker headers add more aggressive sound? Thanks,

 

You might want to get a new fuel filter, that can cause MPG to fall.

By throttlebody do mean a bigger throttlebody or did you mean one of those throttlebody spacers? If you meant spacers, save your $, they give you no gains on a fuel injected motor.

To gain a few more HP and some MPG you might to look at getting UDPs and e-fans.

 

97XL,

Yes, I was referring to throttle body spacers. I've always heard mixed emotions abt em but nvr heard anyone w/experience on the 4.2.. What are UDP's and E-fans, wht do they do, and where can I find em, thanks man

 

Stay away from JET also!!! They do nothing for our trucks!!

As far as you idle problem, check vacuum lines to start, and change the plugs and fuel filter.

When it comes to mods, go with an exhaust (Magnaflow, Flowmaster, Aero). I prefer magnaflow, and that is what my set-up is. I have a link in my sig! Get a K&N, S&B, or Air-raid CAI, and if you want more, spring the $$$ for custom tunes (VMP, Troyer, PHP). Also cutting out the stock 4 cats and reaplacing with 2 highflows will help. Dont know much about the headers.....

UDP=underdrive pullies, which allow you to free up more power from the engine by freeing up the amount of crank power used driving AC/waterpump/etc.

E-fans are electric controlled fans that replace the stoc mechanical fan. They are lighter in weight, and dont use the engine to turn them, therefore freeing up more power. They also help MPG and give you colder AC. I plan on these next summer!!

Welcome and keep you wallet handy!

 

i recommend getting the K&N air intake. I like it because it is a world-renowed company and i use their filters in my plane. i know others offer a tad more power, but it is the only CARB-cert'd (required in california) and has a 1,000,000-mile warranty!

 

WTF? You have a plane too?

 

If you want more power, leave the ENGINE alone!! Put in some lower GEARS!! None of the things you're considering will actually give you enough of a power gain to justify the cost.

Mileage? Maybe someone else can help you with that one. My 99 4x4 4.2 manual transmission averaged about 12mpg. For comparison, that's about the same as my 05 Supercab FX4 5.4

 

What the heck did you do to that thing?? Drive it at 5000 RPM the whole time?? The worst I have ever seen is 13.8 (most recent tank) and I have a 4.2 Auto, Scab!

 

HAHA......I don't know WHAT I did?!?! That's why I said I'm probably not the best person to ask about mileage.

True.....the truck only knew 2 speeds: wide-open and stop! I usually shifted around 4500. If I was in a hurry, I didn't shift till I hit the rev-limiter.

But seriously, the rpm's didn't seem to have an effect. With highway-only driving at 70mph, I got 14mpg.....in both 4th and 5th gear. I tested this several times.....no mileage difference at all. I never checked to see what the mileage was in 3rd gear at 70mph.......but I suspect it would have been a little less ;-)



.....mileage calculations were with 265/70-16's I never checked it with the 35's.

 

I would have hated to see what it was with the 35!

IDK either, but I do love the way you put beefy tires on L rims!!

 

Hey thanks!! I did the inside too......

 

nice. wish i could get that for my Scab....but the 'ole clothe seats are good enough for my bum!! lol

 

i always wanted to see a truck with lightning rims and big tires
and it looks siick wish i cood afford some...