Truck Is Getting Terrible Mpg

[scagle777]

Here lately I've notice I'm only getting about 260 miles on a tank of gas. About a year ago I was getting about 380. I have changed spark plugs about 5,000 miles ago and the air filter the other day. Has anyone else notice a drastic drop in their mpg? It seems like the gas isn't very good. I'm not sure why my truck mpg are so poor now.

[hockeypro1411]

Could be the winter blend fuel, but you live in the GA, so I doubt they even change it. Maybe different driving habits? Then again you do drive a vehicle with enough power to move a house, and the aerodynamics of a piano, so I don't know what to tell ya.

[MarkD]

Locally people are complaining about losing 1 mpg to 10% ethanol fuel.

 

Don't know about cartersville, is that near statesville?

[scagle777]

Could be the winter blend fuel, but you live in the GA, so I doubt they even change it. Maybe different driving habits? Then again you do drive a vehicle with enough power to move a house, and the aerodynamics of a piano, so I don't know what to tell ya.

 

 

I drive with a light foot. I don't understand what it coud be. Guess I'll just have to keep tuning it up until it gets better.

[scagle777]

Locally people are complaining about losing 1 mpg to 10% ethanol fuel.

 

Don't know about cartersville, is that near statesville?

 

 

I don't think so. It's about 30 miles nw of Atlanta. I've lost about 4-5 mpg

[nbscanuck]

fuel filter change may be needed

[scagle777]

fuel filter change may be needed

 

 

That was going to be the next step

[gmblack3]

Just turned 16k on my 07 SD 1500.

 

Computer said I only got 16.2 to 16.4 on my trip to and from Central FL last week. I was cruising at 80 for about 80% of the trip, the rest at 85. I even filled up at a BP in FL before I left. I always run 93.

 

Back in Nov of 07 when I had 2200 miles on the truck I drove it on a 1500 mile round trip. Cruising at 87 thru the TN mountains I got 16.1 on the first tank. Cruised at 80 for the next tank and got 18.1.

 

So I guess this gas does suck with the 10% crap blend.

[Ex-Clerk]

Shannon

I noticed in another post that you had removed the muffler and are running straight pipes. I don't know about Chevys but the Ford 5.4 needs a certain amount of back presser to operate properly. Check with somone who has some expertise and see if this could be part of your problem.

 

Kenny

[66nova]

This may be a silly question, but it didn't drop around the same time you got your exhaust did it?

 

When I put new exhaust on my truck my mileage dropped quite substantially for a good while. I can't really blame it on the exhaust, but I liked to hear it. I did not ever really get on it, but I gave it slightly more gas then I would have before, and I may stay in it just a hair longer. I really didn't realize I was doing it at first until I started calculating my mileage and said whats going on.

 

It does not take much at all to drop you average mileage a few mpg. Pushing down on it one time just a little harder than usual can ruin the average for that tank.

 

BUT I would definitely change the fuel filter. It's good for maintenance and it may help your mileage.

[norsemanberg]

You should clean up your throttle body as well, I am having the same problem up here in wisconsin and I'm doing the same thing you are ( one thing at a time to figure out what exactly the problem is) and I found that after i clean mine up really good my MPG bumped up by about 1. Good but not enough so back to work! Let me know if you find any thing that makes a big jump in the MPG.

[66nova]

You should clean up your throttle body as well, I am having the same problem up here in wisconsin and I'm doing the same thing you are ( one thing at a time to figure out what exactly the problem is) and I found that after i clean mine up really good my MPG bumped up by about 1. Good but not enough so back to work! Let me know if you find any thing that makes a big jump in the MPG.

 

 

You should probably put a bigger throttle body on it. It will get like 40mpg then.

[2018GMC]

How many miles are on the truck? Has the 02 sensor been changed?

 

http://www.boschautoparts.com/Resources/FA...ygenSensors.htm

 

Depending on what type of 02 sensor it should be changed at 40k 60k or 80k

 

Yes if you 02 sensor is bad it will throw a check engine light but only if it is way out of limits or dead. Most sensors will slowly die - functioning slow - negatively effecting your mpg.

 

Depending on your truck you may have up to 4 sensors. Usually they are located before the CAT, in, after, or both.

 

My local exhaust shop said that if they are before the CAT you can safely remove the cat (may be breaking emission laws), if they are in the CAT, after, or both you must keep your CATs or else your truck will get horrible mpg and prob run like $hit.

 

We replaced all (4) o2 sensors (Had a rich mixture engine code) on my buddies 97 350 and mpg improved 2mpg and had more get up and go.

 

Usually you will notice 10% to 15% increase in mpg if your 02 sensor(s) are worn out.

[ace ventura]

I see your running 285's. If you didn't adjust for tire size it will show a reduction in fuel economy.

[scagle777]

My truck has right at 100k on it. It's been getting terrible gas mileage the last few tanks. Before any exhaust change.