Hey guys I'm curious as to what to look for behind the cause of my horrible fuel milage. I have an 02 7.3 170k auto. Stock tires and height. Doesn't seem to have any boost leaks and has a chip intake and exhaust. I'm getting like 11-12 mixed Highway and city. Mostly Highway as I travel about 40 miles round trip per day. I'm not sure what else to check for, any ideas. Help appreciated!

 

Have you put a boost leak detector on it? What about exhaust leaks? What about the EBP tube? Which chip? Which intake? What gear ratio? What rpms? Got a brake caliper dragging? Tire pressure correct? Many things to check...

 

Often a blocked EBP tube or a bad EBP sensor can result in bad fuel mileage ..... As suggested by kjndiver check the EBP tube to see if it's clogged and use a scanner or something like Auto Enginuity to compare the EBP sensor to the MAP sensor & Baro sensor readings.

 

Hey thanks for the reply guys. Does anyone know of a good write up for checking the ebp tube? Also I have a snap on scanner at work with the program what do I need to check? Like what are the names of the numbers I should be checking?

 

Also it has a home made intake with k&n filter. I think it was a spectra kit originally. Ts6 with factory tunes. I don't believe any brakes are sticking. And gears are stock 3.73. I have been running the tires at 65 unless anyone feels I should adjust them?

 

The tire pressures on your door are what the truck was designed around, not only for stability, but for tire wear also. If you rotate your tires regularly, then they will wear evenly unless there is some other issue. The EBP sensor is on the front of the engine, towards the top kind of to the right side of the engine. The tube is below that going to the manifold. A lot of us use and old speedo cable in a drill to clean out the tube with some brake cleaner. Letting the sensor soak in carb cleaner overnight then hitting it with a soft blast of air in the morning cleans them up, as they get clogged too. If you have any oil film around any of your intercooler boots, then you have a boost leak. if you see streaking in the film, then it is a bigger leak. Exhaust leaks behind the turbo at the "babies butt" will leave soot on your firewall indicating an exhaust leak there.

 

Hopefully you find my videos helpful.

 

Good post A/Ox4!

 

How are you getting those MPG numbers? If it's from the overhead instead of hand-calculating - the overhead lies, then a chip makes it tell titanic tales.

Soot is bad on a stock truck. Soot out the back says you're lacking air or the fueling is getting carried away - this could be a boost/exhaust leak, or something as simple as a bad ICP sensor. Exhaust leaks reveal themselves in the form of soot under the hood somewhere - soot doesn't belong there under any circumstances.

 

Hand calculation. My overhead actually says 19.1 right now lol. So somewhere my computer is thinking it's getting better mpg. I understand it's not gonna be perfect but why the 8gal difference? Also no sign of soot anywhere in motor bay.

 

After you checked & cleaned the EBP Tube, see if you scanner will let you monitor the:

Exhaust Back Pressure Sensor (EBPS)
Manifold Absolute Pressure (MAP)
Barometric Pressure (BARO)

On a cold engine, with the Key on the on position and the Engine not running.....the 3 sensors should be within .2-.4 PSI of each other.

so, if you are at an elevation of 1,000 ft above sea level the sensors should all read about 14.2 psi (+ or - .2 psi). If you are around 3,000 feet the sensors should read around 13.2 psi (+ or - .2 psi).