Spark Plugs for better MPG's

[Nathan16341]

I have an 05' MT with 76,000 miles and last time I checked, I got 320 miles per tank at a 14.5 gallon tank. If you do the math that's 22mpg almost all Highway! That sucks. I am running all Amsoil fluid with a K & N air filter. I am hoping putting new plugs in will boost my MPG. Besides replacing in the original plugs, what have you had luck with?

[CadenceScion]

If your going to replace Spark Plugs, make sure you get NGK's (Double-Platinium) or (Iridium). Another suggestion would be to clean the Throttle Body w/ throttle body cleaner and a bottle of Fuel Injection/Fuel System Cleaner (Chevron w/ Techron, Lucas, STP, Gumout).

You could also try spraying your MAF Sensor w/ a MAF Sensor Cleaner.

[Nathan16341]

Thanks bud, I hope it makes a difference.

[CadenceScion]

Your welcome!

[navylife59]

I get better MPG than that with my S/C. With 75K miles on it, some things that could be chewing up your mileage is a slipping clutch or worn-out O2 sensors. In cruise on a flat highway, the load on the clutch is light. You would know your clutch is slipping when accelerating. Have you have changed your trans-axle fluid? A good synthetic gear oil would help some. Tires and inflation can play a large role in MPG efficiency. Do your tires make alot of road noise? Do they feel extremely hot after driving on the highway? If so, that could be signs of increased friction from the tire's tread blocks and materials. Replacement is the only option here. Properly inflated tires is critical as an under inflated tire creates alot of friction. I run 32PSI all around but you can just follow the OEM recommendation on the Driver's door jamb. Dragging brakes is another known culprit. The caliper pins and bushing grommets could be dry or gunked up. This can lead to a brake pad that stays in contact with the rotor. Very shiny and/or grooved rotors is a sign of this happening. If so, would suggest rebuild the calipers, replace/turn the rotors, new brake pads, and flush/replace the brake fluid with a better than OEM replacement. Parking brake cable can be taut and cause the parking brake shoes to remain engaged. These shoes are small so it would only be a problem for a short time like 100 miles or less.

How about your air filter? Been replaced or cleaned (aftermarket oiled) lately? Wheel bearings worn can be yet another issue when getting near the 100,000 mile mark though it is unlikely. Is the car running rice due to some engine mod? Of course, there is the issue of driving habit but I take it that you are comparing previous mileage with similar driving habits. How much Ethanol is in the gasoline that you purchase? The more Ethanol the less MPG you will get. How are you calculating your fuel economy?