Im prety sure my turbo does have the "lag master" housing, but like you said doesnt explain a sudden drop, and its still boosting like it always has.

 

my 09 powerstroke gets around 7 every day.

 

If I pull a trailer and drive as hard as I can, I can't get below 10 mpg.

 

me too...

 

If its smoking more than usual maybe a boost leak? You have a boost gauge?

 

I have the lagmaster and i still pull 20-21MPG unloaded, no mods yet though.

 

At $3+ a gallon, that's gotta hurt.

What better reason to drive the 1st gen more!

 

What is an acceptable mpg, for normal city driving w/a '93 D-350 auto, no major upgrades except turned up fuel screw, and 4" exhaust.

 

16-20 in town, 18-25 highway unloaded. 2wd with 3.07's out back and a 5sp might get ya close to 30 empty highway. The autos loose a lot to the sloppy converter, when I got mine replaced I picked up about 3 MPG.

 

In my 92 d350 I get 17 as a low in town when my fuel filter starts to get old and I'm in need of an oil change. Been consistent like that for years now. Definitely got something wrong with your truck. I'd be scared about it if mine got less than 15 even towing.

 

Taht's what you'd think but at 70 a 3.07/5spd setup is kinda luggish most guys that have it run 80-85 down south and get like 23....i think rbrettctd has that setup and a few others.

Doesn't work like you'd think because a VE motor likes about `1900-2000 rpm.......

I think the 3.54/5spd combo is the sweet spot at about 68-70...
-I know when i drive the 93 now with 265/75 on the back the sweet spot is about 68mph....as soon as you go over that 68mph it starts making more noise and the turbo makes a high pitched whistle lol...even 70 makes a difference.

the one trip we made late at night we were doing 80 the whole way taking turns driving and that tank was like 17.8 which i thought was respectable

i think timing makes a difference too....because it gets 20.7 around town and that's insane if you ask me. my mom

But when half of your tank is free waste motor oil anyways....who cares what your mileage is!

 

have you pulled an injector? What does the tip look like? If its coked, it will give poor mileage and more smoke due to poor spray pattern.

 

Does it haze at idle or while driving? I had 3 injectors with cracked tips and I was getting between 4-7mpg but that was towing heavy. Empty it was 12-15.

 

unless your leaking it or pulling a 15,000 trailer it was stolen I have a17,000 trailer and still get 10mpg min. it would be pumping out the dip stick if it was bad injecters or wash out a cyclinder.

 

My truck has a boost guage, seems to be boosting normal.