Decreasing fuel economy / gas mileage

[pmatejcek]

I bought a 2006 V6 in... oh, must have been about 2009. It had about 30,000 miles at the time. My gas mileage seemed to run around 24.7 mpg.

Four years later, at 93,000 miles, my mileage seems to run about 20.8. The tappets have always seemed a little bit loud, but Toyota says they are fine. Except for that, the engine has been unremarkable. It still goes like a bat out of hell if you floor it -- which I only do for the occasional pass.

Is there anything that I should look for? Does it make sense to change the plugs? (I've never changed them, and I doubt that the previous owner did.) Anything else I could look into? Any application for my laptop-based Elmscan OBD reader? Or should I just chalk it up to age?

Paul in East Troy WI

[Scout706]

Maintenance? Air filter? Check engine light?

[ronbo1313]

Fuel injectors might need cleaning. Do you use a TOP TIER gas? An oil analysis will tell you if you have a trace of gas in your oil.

A can of Gumout with Regane or another high quality fuel injection cleaner and I hear the Toyota dealers sell on of the best, may help?

[wrczx3]

Maybe the gas didn't have ethanol back then?

[lance]

I just bought an 08 and the mileage is not what i expected, going to do all that maintenance stuff once it warms up a bit and see what happens

[03rav4inPA]

Every 10k check your air filter...also run some Chevron Techron through your tank every other other oil change...keeps your fuel system components clean!

[olds362]

With modern fuel injected engines, the air filter will not make that much of a difference. The computer will compensate and change the amount of fuel to match the amount of air flowing into the engine. You should still change your filter regularly but it will not affect gas mileage like it used to.

[pmatejcek]

Originally Posted by Scout706

Maintenance? Air filter? Check engine light?

Thanks to all who replied. (I didn't realize that there were replies -- I expected an email telling me if anyone responded...)

Maintenance: I change the oil and filter, variously from 3,000 to 5,000 miles. Have not done the air filter in a while... No CEL. Starts easily, runs smoothly.

What about the plugs? Should I be concerned about them? Pull one and have a look? I'm thinking that replacing the rear plugs is a PITA, and I understand that the factory plugs have a very long life. But I'm just about at 100k... It's winter in Wisconsin, not a fun time to work on a vehicle in an unheated barn. Am I really asking for trouble by replacing the plugs, or am I well advised to take it either the stealership or my favorite Firestone mechanics? I wonder what Toyota would charge to do it. I have to take it in for a rear suspension recall anyway...

Thanks also for the advice on additives. I'll try some injector cleaner. Does anybody out there use Seafoam?

Paul in East Troy

[vanib]

Like you mentioned, your spark plugs are good for another 7K miles and those who took it out mentioned that it looked like new! So I would postpone this for warmer weather.

I have changed the spark plugs on my Mazda V6. Although it took 3 hours to do that job (I had never done this kind of job before), I was able to open the Intake Manifold reach the rear plugs within 20 min the next time!!!

Since there are DIYs on this forum for the plug change, I would definitely attempt it.

[RTexasF]

Originally Posted by 03rav4inPA

Every 10k check your air filter...also run some Chevron Techron through your tank every other other oil change...keeps your fuel system components clean!

I concur. Cleaning the throttle body is also in order.