Just took delivery of my new truck and even though I've had trucks with the same engine and the old 7.3 D, I can't believe the poor gas mileage and lack of power in this truck. It is an '08, 4x4, xlt, 3.73 and now have 700 miles on it. Mileage stinks and power is worse.

Can I improve matters with a tuned exhaust or air injection system. I know most chips are BS and even though I realize things will improve somewhat with time, I really think I need to do something.

Any advice?

 

Maybe it would help if you provided some details like what kind of mileage you are getting. Describe the lack of power - acceleration? hauling? towing? etc?

What kind of trans - auto or manual?

Anything else you can think of would be good. Some of the more knowedgeable folks can then chime in with some ideas/suggestions.

 

Yeah, what's mileage stinks mean?

 

You got the wrong gears for one. With 3:73s your putting a lot of load on that poor little 5.4l. Also the 5.4l 3V only has 300hp and 365lb tq, couple that with a 7k lb truck and a VERY bad 3:73 gearing and you will get a truck that don't move for crap or get good mpg. (As far as a truck goes) Do a gear swap to 4:30s and you will pick up a noticeable power boost. An intake and exhaust will give you minimal gains and a tuner will give a decent 20hp increase but you will need to run 93 octane gas.

 

Dude, c'mon man. Redford...git 'im!

 

Sometimes the truth hurts. 3:73s are not good gearing for decent performance, towing or hauling around a heavy truck. I have 3:73s on my truck currently but I have the V10 with mods done to my truck and I know 3:73s are hurting performance, I'm swapping to 4:30s eventually, just not in the budget right now. Also take in to account that the 05'up SDs heavier than the 04' under SD. Notice the same truck with the 3V V10 is not offered with 3:73 gearing and the V10 has gobs more power than 5.4l 3V. I have no problem with the 5.4l, its a good engine.

 

Only true if your wanting to realize the entire potential of the tuner. You can still change other things that might actually help(if the truck is an auto) match the way the truck acts with how the driver acts and not have to worry to much with hp/tq and thus eliminate the need for the 93.

 

While I don't have the 3v motor, It took a tuner, 4.56 gears, valve body, cold air, headers and exhaust to make it move. It's still not quite what I want from a lazy launch, but it has chirped second.

 

You got a nice truck. Did you replace the necked down y-pipe section on your truck? I replaced the Y on my truck before the headers and it helped the low end power quite a bit. My dad has the ebay y on his truck, and its working good for him.

 

I know, I was just letting the guy know power wise what to expect. A good tuner is a valuable tool that I won't go without.

 

I'd love too, but I haven't found a bolt on one yet. All I can find are the v10 y-pipes and no-one can tell me that it will fit. Plus I want the Y-pipe to be more of an X pipe that's missing a leg than the reduced diameter intersections.

 

The ebay y-pipe will fit right in, you cut out the old section and weld in the new ebay section. Both the 5.4l and 6.8l have the same y-pipe setup after 2001 or late production 2000. The stock y-pipe is alright except for the necked down portion. The ebay pipe comes in stainless or aluminized. You have the V8 so you do not have to worry about flutter. The stock y-pipe was designed like it is to eliminate flutter from the V10, the V8 doesn't produce flutter.

He says it also fits the 5.4l
eBay Motors: Stainless 00-04 Ford F250-F350 6.8L V10 Exhaust Y Pipe (item 220231758451 end time May-14-08 23:12:36 PDT)
eBay Motors: 00-05 Ford Excursion 6.8L V10 High Performance Y Pipe (item 220232516851 end time May-17-08 01:41:08 PDT)

 

I really wanted to try it without cutting my stock one apart just in case it fluttered more than I could stand. Banks, JBA and another company had a listing for the V10 bolt on Y-pipe and that was more what I am in the market for.

 

Sorry about the confusion. The truck is an automatic trans and the power concern isn't really dramatic pulling away from a stop but rather maintaining highway speed going up slight hils... The overall mileage is < 10mpg and highway at 65 mph is <15 mpg. Can I expect this to improve with break-in and a more impt question is - will any of the chips on the market actually help. I plan to occasionally pull a 65oo# boat and envision a less than enjoyable experience. WHY THE HECK DID THEY STOP MAKING EXCURSIONS - I loved all 3 of mine (all diesel).

 

Doc,
Your 5.4L will wake up quite a bit after breakin, 2000-5000+ and mileage will increase. I had the same thought when i bought mine but i babied her and didn't have my foot in her too hard. Of course if your towing with it even ocasionally you probabably should have opted for the V10 or diesel. But regardless do the gear swap, chip and exhaust and intake mods. Although the gear swap will opt the best performance and the others will only yield minimal hp numbers.