New Air Filter and Bad MPG

Hello All,

When I did my last oil change at 9k I installed a new Wix air filter.

Now my gas mileage has dropped from the mid-19s down to 17.5 and 17.8 on the last two tanks. I definitely was not expecting that. If anything I expected it to go the other way.

Any ideas? I am getting gas from the same station and the same pump. I have an 09_DC_LB_V6.

That is the only variable I can think of that has changed before and after the oil change. I am using 5w30 dino oil. Which is what I have been using since the first oil change.

Ideas / Suggestions?

TIA

 

Is it a "free flow filter"? Similar to a K&N? If the motor is getting more air it will detect than and dump more fuel in.

I stick with the Toyota air filter. Their engineers put a lot of time and money into matching the right parts together.

If nothing else has changed but the air filter, I would imagine that is the problem.

Have your driving habits changed? New way to work or anything?

 

make sure you use the oil from the book or fill cap, mine says 0-20 or 5-20 weight ,but its a 4 cyl.
could be the brand or quality of oil, most dont really make a difference imo. When i changed the toyota oil out for store bought dino oil (wish i could remember which top brand) mine went down too.
2mpg change can be easy considering little variables through a month, a leaky tire?, wind direction, 15 degree temp change, more red lights than normal

 

Just a replacement filter to the OEM paper filter. I may go ahead and trip over the the dealership and get an OEM and throw it in before the next tank and then see how it goes.

I don't think my habits have changed. Same old route to work.

Thanks

 

I am using what it says on the fill cap. Which I am pretty sure is 5w30. Pennzoil is the brand. I have done two other oild changes before this one and the gas mileage never changed.

 

I was thinking about this, if my new filter is allowing more air in and thus as you say more fuel, then it seem the engine would not be working as hard. Hence better MPG.

I was even thinking about removing that carbon filter in the breather to make for better airflow. But was worried about warranty and such.

Now I think I am confused??

Thanks again!

 

Maybe to most parts of the truck...but possibly not the air filter. Keep in mind that they have a budget to work with. Vehicles are created with cost limits, and therefore certain items are by no means performance based...they are often "good enough" to get the job done.

 

Wix makes quality stuff I used them on many vehicles oil and air filters.
I do not think it would cause a drop in mileage all by it self.

 

how much do the toyota filters run?

 

I think the logic is that the ECM attempts to maintain a specific fuel:air ratio for a given throttle setting. If the air filter permits greater air flow at that throttle, then the ECM compensates by metering more fuel to maintain the fuel:air ratio. Thus, more fuel consumed for a given throttle.

Of course, I could be wrong...

 

That was my thoughts also. I use their oil filters also.

 

Agreed. But would that not imply that it takes less throttle with more air/fuel to do the same work than a system producing less air/fuel?

I am getting a headache!

Thanks

 

So following along with the more air more fuel logic. Would removing the carbon / secondary filter cause it to use even more fuel??

Thanks again

 

I suppose, if the ECM were only monitoring fuel:air. As I understand it (or misunderstand it), it's also monitoring the throttle position and timing, and adjusting the latter for whatever fuel:air + throttle it reads, according to its programming.

One of the effects of a black box doing all the work is that you don't have to adjust a carburetor or reset the timing for optimum (read "stock") performance when driving from sea level to Denver. Ahh, those were the days..

 

So, ok,

Yes more air means more fuel. BUT! also means more horsepower. This means it will take less throttle to maintain the same speed. In general, a better flowing filter should improve gas mileage since you get more oxygen in the cylinder promoting burning a larger amount of the fuel and improving efficiency.

 

good thread...

 

A normally aspirated engine will only pump as much air as it can pump. You could take the intake manifold completely off, and the engine will still only pump what it can pump, and that is a function of bore, stroke, 2 or 4 cycle, number of cylinders, and rpm.

I don't think that the stock toyota filter is "restrictive" to the point where even removing it would get you any better resistance to flow so I doubt the filter is the problem.

 

A motor will pump what it can pump. Jam the intake with cotton and it will still try to pump what it can pump but wont be able to.

The motor sucks air. Try to suck air through a cotton shirt, then try to suck air through a piece of canvas. It easier to suck through the shirt. Some of these aftermarket air filters are too free flowing, I am not a fan of them. I guess a true test would be to put the OEM filter back in and drive it.

 

I disagree. I think the difference is negligeable. I think there's something else going on.

 

hey guys...

i just installed a custom intake on my 09 trd sport dc lb, and my gas milage has stayed the same if not improved slightly, im around 19 when i filled up yest...and im 21 and noticed the extra power so of course i just had to drive it hard =)))

but it may be just that not every truck is not the same depending on break in and mods and stuff so idk...just wanted to throw my opinion out there