I'm getting 1 mpg less (combined) lately. I'm running 35 psi in the tires. It only has about 29K miles. It has gone from 18.6 to 17.6...not much difference but the consistent 35 psi should at least contribute to slighter more mpg.

I got a free nitrogen-for-air replacement a couple of months ago in the tires. My driving habits haven't changed except that I probably hit it less. Most trips are about 20 min. so it's fully warming-up.

I wonder if just some BG 44K might help. What about Sea Foaming the intake manifold;will that help with mileage?

 

my mpg usually goes down 1 or 2 during the summer due to heat. The air going in is less dense, so less power is made which in turn leads to a heavier foot. The ac running is also a factor.

Derek

 

It was getting 18.6 for 3 years. This is a hot and humid climate like yours so we use ac for about 10 months out of the year.

1 mpg is minor;was just wondering about possibilities.

 

That's weird, mine has gone from 17 (winter) to 19 (summer). In the winter the oxygen in the air is denser thus causing more fuel into the combustion chamber.

 

Have you thought of maybe changing your spark plugs? They're "supposed" to be high mileage plugs, but I always change mine every 30K miles max.

 

I get two or three mpg's better in the summer despite using the AC. From what I have read it is due to the change in gasoline forumulations between summer and winter. Are all your vehicles getting less mpg's or just this one?

 

true!!!

 

I only have one.

 

Actually, it's based off MASS air flow, not volume; it doesn't matter what the air density is. To make a certain amount of power, you need a certain amount of fuel which means a certain amount of air (mass, not volume) because you keep a constant air:fuel ratio.

You are right that you may have to open the throttle body more, but the same MASS of air is coming through to make the same amount of power.

If anything, thinner air is better for aero (really, that's negligible); the biggest difference, as stated, comes from getting rid of that winter-blend ****. I can tell exactly when winter blend comes in because my MPG drops by 2 or 3. Warmer air can also be better because colder air will wick away heat from the engine.