Need advice on what i need to do be4 i change spark plugs on a 05 maxima

[spuka02]

I have an 05 maxima and a week from now i will be changing the spark plugs , serpertine belt to see if fuel mileage improves i am only getting 12 miles per gallon city and highway combine and that is bad i should be getting at least 18 in the city and like 23 in the highway . I always change my oil on time to Castrol 5w-30 . The has 50,000 miles on it i know is too early to change the spark plugs but do i need to change anything else while i am changing the spark plugs

[MinisterofDOOM]

If you're getting 12mpg combined, something is seriously wrong. You should be getting double that. I doubt spark plugs alone are responsible. Is your check engine light on?

[MaximA32]

At that mileage, MoD is right, something else entirely is wrong. I've got an 04 SE with 124k on the clock and I still get 25 on the freeway. Give everything the once over. Set your tire pressure to the correct setting, make sure your air filter isn't clogged and run some Gumout Fuel System Cleaner through a full tank. See where that gets ya. If your check engine light is on, something is up with fuel delivery or emissions that's causing the car to dump fuel. Does it smell like gas when it's running?

[infinitidude123]

Check the plugs to see if they are fouled or not. Something is telling the engine to use more gas. A coolant temp sensor if malfunctioning could fool the engine into thinking it is cold, and will cause the fuel air mixture to be too rich, and could cause poor fuel economy. How is the driveability, does it idle rough? Find a reputable mechanic and have diagnostics run on it to see if any other emission control sensors are bad.