I have an 03 QC 4X4 5.7 with 93k on it. I bought it with 68k. When I first got it I was averaging around 13.5 mpg with a mix of prob 60%local and 40% highway miles. Now im lucky to get 12 and recently got 10mpg. In that time I have replaced the after cat o2 sensor, cleaned my throttle body and air filter which brought me from 11 to about 12mpg. I am wondering how I can get back to at least 13mpg again I am hoping to get 15 if possible The price of gas is killing me. 89 octane where i live is about 4.25 a gallon. I have an AEM CAI and a gibson cat back exhaust. I am wondering if removing these will get back some mileage. I am very easy on the skinny pedal as well. Wil replacing the spark plugs help? The engine runs very well though so I dont know if it will make any difference. Is this normal mpg for one of these trucks? I am just frustrated. I dont want to have to get rid of the truck.

 

You could try a good injector cleaner, you may see improvement.

Plugs should be checked, replace if needed.

Efan mod can get mpg increase quick & can be low budget or fancy kit.

 

If you have 93k on the engine and have not replaced the spark plugs then you are dead wrong. If they havent been replaced in the last 30k then you need to replace them.

Other things to look out for are weight reduction, proper tire pressure, front O2 sensor, non-ethanol blended fuels, electric fan conversion versus clutch fan, keeping the RPMs lower. Resetting the PCM also helps

Thats all i can think of right now.

 

great suggestions. i wll definitely replace the plugs when the weather gets a little better. Any suggestions on type? And i didnt even think about the electric fan mod, ill look into that. Thanks!

 

Use OEM plugs and we have tons of mods, DIY and How To's in our FAQs. Click on the link in my sig or at the top of the section to get there