11 mpg, and stuck front hubs... help!!!

[jay7.3]

my 99 f250 is getting only 11 mpg with new injectors, high presure oil pump, and cronk sensor. i have replaced the exuast from the turbo back and added k&n filters. i have a diablo sport preditor tuner that has three settings 65, 85, and 110 hp. on stock the tires won't break on dirt. on 65 it runs good but the motor surges for a few seconds before settling to a smooth idol, first thing in the morn. the higher i set the tunner the worse it runs. on 110 the injectors clatter like crazy and the truck is sluggish. i love my truck but will have to sell it if i can't get good milege without breaking the bank. (poor boy's got poor ways) lol

then there is the hubs not disengageing. i don't play in my truck but use the 4x4 often wether it be in sand or water. i know that i am loosing mpg there also. when i put it in 4x4 the ac vents change to defrost for a while. i can't really afford new hubs at the moment while recovering from the injector job. is there a way to use the factory auto hubs as manual if i disconnect the vacuum lines to them and do some cleanning as i am sure they need it.

any advice would be great!

[dmd]

Just remove the hoses from the hubs and use the knob to turn them.

What does your turbo look like? Also, if you have the stock air box with a K&N
you will dust that engine if it isnt already.

How did the truck run before the work?

[jay7.3]

Originally Posted by dmd

Just remove the hoses from the hubs and use the knob to turn them.

What does your turbo look like? Also, if you have the stock air box with a K&N
you will dust that engine if it isnt already.

How did the truck run before the work?

i'm sorry i don't know how to answer that question about the turbo. it has a metal hose system that runs to a y over the motor and to the cooler in front. the turbo looks old, the exaust side is rusty. how would i know if i have dusted the motor? i don't mean to sound dumb this is my first diesel truck.

when i got it was sluggish and got 16 mpg. i put the tunner on it at 65 and it blew my mind. it had so much power and 22mpg, that was a year and a half ago. the changes were suttle and slow. it wasn't till i took a long road trip about six months ago that i noticed the mpg was horrible then i started noticing a loss in power.

[Twinjracing]

K&N is stock box bad????? that what i got on my 01 ex for three years now and still runs fine.

[Dave]

The hubs not disengaging will cost 2-3mpg.

What you have is a vacuum leak. Most likely at the hubs. Find the leak Fix the leak.

Replace your hubs with Warn Premiums. Problem solved.

[Mikey's250]

Originally Posted by Dave

The hubs not disengaging will cost 2-3mpg.

What you have is a vacuum leak. Most likely at the hubs. Find the leak Fix the leak.

Replace your hubs with Warn Premiums. Problem solved.

I found my leak to be at the hubs but I cant find where it is. Is there a seal in there somewhere or what?

[Rowe80013]

There are several seals in the front hubs. I'm in the process of replacing the seals and bearings in my right front hub right now. I have warn hubs and they work great but the bearing that holds the axel shaft inside the wheel bearing is so worn out that the hub drags and like your situation, wont disengage sometimes. There is one yellow o-ring type seal that goes around the wheel bearing carrier that I believe does most of the vacuum sealing but there are also other seals that may play a part. I also recommend switching to a manual hub as my pops has the stock hubs and is always having trouble with them. Good luck

[greenearth808]

my truck turns on defrost when i engage 4x4 too. Is that what its supposed to do? If not what's wrong?

[ju015dd]

Originally Posted by greenearth808

my truck turns on defrost when i engage 4x4 too. Is that what its supposed to do? If not what's wrong?

vacuum leak

[Degnol]

Don't you have to back up three revolutions to disengage the auto hubs? It was that way on my F150, but they were straight auto, not auto manual like my '99SD