8 Mpg?

[alpinestar]

Why am i getting 8 miles per gallon? i have the 2.9, completely stock except a flowmaster muffler and the truck seems like it runs good. so im getting about 160-170 miles a tank and thats horrible. so whats the deal?

 

[tpking]

what size tires and gears? clogged cat can make for bad mpg's

 

[PetesPonies]

with an injected engine, mpgs can be really fouled up by a bad O2 sensor. It can enrichen the mixture when it is not needed, its a feedback sensor. It tells the computer how to fine tune the results. But when they send inaccurate info, it can really lower the mpgs. Its the one sensor that should be replaced every 50K as a tune up piece. They degrade.

 

[Mechanickid]

check the timing

 

[alpinestar]

i have 31" tires and 3.73's and i will bust everything out of the cat if its necassary and how much is an 02 sensor?

 

[2low]

doesnt james duff sell a cat eliminator pipe?

 

[Shran]

Test your coolant temp sensor first. Known problem on the 2.9.

 

[Hahnsb2]

Because you're measuring your fuel mileage wrong.
How many gallons are filling up with when you're on E?

 

[alpinestar]

im not even filling up with when i do it. i normally put 10 bucks in with is about 3.8 gallons around here. so i run my gas gauge til it gets back down to where it was when i filled up and its only about 30-35 miles. and ive tested to see how far down my guage goes past E and its doesnt at all. i have an aftermarket gauge and when my gauge gets right to E it is completely empty. left me stranded in the middle of a busy road one day

 

[Jason]

I would read into what Hans is saying. I am not even sure a 2.9 can pump fuel through the engine that fast without a fuel line leak.

 

[Shran]

I would read into what Hans is saying. I am not even sure a 2.9 can pump fuel through the engine that fast without a fuel line leak.

You would be surprised. I was getting 10 on the highway with one of my 2.9s before I replaced my ECT...that is why I suggested it.

 

[alpinestar]

oh trust me it can... cuz it is... plz if you like i'll let you pay for the fuel for a week.. its rediculous. luckily im about to swap in a 4.0 so if this doesnt help it (i just put a new o2 sensor in and havent got to drive it since yet) i will get that 4.0 in soon!!!

 

[martin]

If you're getting nearly four gallons for ten bucks you must have some really cheap gas where you are. It's around a buck a liter here so we get less that two and a half imperial gallon for ten bucks.

 

[Hahnsb2]

You NEED to fill it all the way, drive at least 100 miles and fill up again to get an accurate read on your mileage, your method is no better than blindly guessing. If I tried to guess the mileage by looking at my gas gauge I'd be getting 8 MPG too.
Also rember if you have differen't gearing/tires your speedometer/odmeter is off too.

 

[Jspafford]

Yeah, your reading the mileage wrong. Fill it up, drive 100 miles like mentioned, then top it off again. Divide the number of miles driven by the number of gallons (exactally) needed to fill it back up. 2.9's are capable of much better. Mine has 163K and last fill up got 22.4mpg.