can't get mpg up...

[sms8921]

Ok here's the deal 94 7.3 turbo new IP and injectors, timing set to 8.5-9.3. Truck has 4.10 rear end. New lift pump, synthetic gear oils in front and rear and I still can't get over 12 mpg highway. Pump and injectors now have 5000 miles on them. I have tried driving very easy and very hard, nothing has helped. I run PS additive in every tank. Getting ready to sell it soon if I can't get more mpg put of it. Anyone looking to trade or buy? Lol

 

[thx997303]

Tire size? If they're larger than stock, you have to correct for it. You could be getting more mileage than you think if that's the case.

 

[sms8921]

Tires are 285/75/16 don't know how to figure that math compared to stock tires.

 

[thx997303]

That tire size will travel 3.5% farther than stock tires. So you will need to add 3.5% to your odometer reading to get an accurate estimate on fuel mileage. If you run 300 miles for example, you need to add 10.5 miles.

Multiply the odometer reading by .035, than add the result to the odometer reading.

As it is, you are still likely getting poor MPG, but You're likely getting closer to 13 mpg than 12.

 

[chris142]

How fast are you driving? I can get 15.7 if I stay at 60 and don't try to power up hills. Last weekend running 80 and staying on it I only got 12.6.

 

[justinray]

Hows the air filter look? Does it feel strong when driving, or like you lost power? Tires properly inflated? Any of your front accessories on there way out (ie. power steering pump, water pump, vaccuum pump, alternator)? Is the alignment in spec? These are all the normal factors that all play their own little part in killing mpgs, while it may be something else, usually these are the more common culprit.

 

[justinray]

Also, what Chris said, every 5mph over 55 is 10% more drag on the truck, and the drivetrain.

 

[sms8921]

New water pump up front. Everything else seems fine. New alignment last fall, tires good on pressure. I drive 55 or under all the time. Truck feels real strong, almost no smoke when ******* it everything looks and feels rights just mpg sucks..

 

[FORDF250HDXLT]

try bumping your timing back from 8.5-9.3 as you stated to 6-7 BTDC.
i recently turned my fuel up! and retarded timing back to 7 BTDC and i can now make my 8k lb dually box truck hit up over 15mpg (running empty of course lol!)
http://ecomodder.com/forum/em-fuel-log.php?vehicleid=5088
(i know that one looks a little suspicious rolling into the gas station at exactly 300.0 miles on that tank.but it's exactly what it said.)

after a handful more back to back tanks,i;m going to try the lowest spec 6 BTDC and see what happens.

first though,as stated by others,you must have an accurate odo! start with fixing that:
http://www.ford-trucks.com/article/...EDOMETER_ON_9296_FORD_FSERIES_AND_BRONCO.html

 

[riotwarrior]

Taller wider tyres make a difference as they have more rolling resistance, I've got tall narrow ones 255/85/16's 4:10's and ZF and 7.3 NA and routinely get 19+ miles per Imp gallon.

Check yer speedo with a GPS and compare what it reads to what you actually are driving. I've found mine to be effed. so I have to calculate it all out manually...No big deal just basic math!

Whats yer TP set at? What load range of tyre?

It is an E4OD right, is it stock and how many miles on it? Could be that's the culprit too.

What do you weigh in at for the truck?

Lots of variables, are you in hilly terrain or flat land? Lots of city or lots of highway driving?

Need fill in more blanks to offer any real advice.

JM2CW

 

[FORDF250HDXLT]

another thought,
insure your mechanical fan clutch didn't fail in the engaged position.they typically fail in the unlock state,but sometimes can fail locked up.this would really hurt and explain a lot of your low economy too.

 

[sms8921]

Tps is set to spec, fan clutch works great I think I weigh in at like 6600 empty. Just checked Speedo with GPS and it is almost exactly on. I have a recently rebuilt transmission that's had a custom tq and shift kit put in. I drive mixed but I have purposely taken the truck on solid highway rides and have not been able to net over 12 mpg... I will maybe try retarding the timing back some.

 

[Greg5OH]

are you sure you have a diesel converter? The gassers have a much higher stall speed. Is the converter fully locked on the highway?

 

[OLDBULL8]

Better check with Agnem where to set the timing with a baby Moose. I think your not advanced far enough with a turbo, prolly around 10.5 to 11 BTDC. JMO.

 

[sms8921]

Yea it's a diesel tq converter the gut that did it is big on e4ods and a family friend that knows about diesels. I had the timing awry at 10.5 once and I thought it was gonna come apart in me lol.