Engine Air Filter Change

I recently changed my engine airfilter...the original was very dirty (after 25,000 miles of city/tollway driving). I've noticed about an average 2 mpg improvement in mileage since then. Is this possible? Before others respond that it must be related to driving habits, my route, speed and driving habits were essentially identical each day. I figure it must be coincidence, but I do not know how much a very dirty air filter will affect the mileage.

Just curious.

dirty air filters impact mpg on all cars. it's easy to change and usually worth it. if it was really filthy it may have been really affecting performance of your ice.

Thank you. That may very well be it.

Yep a dirty air filter is bad. If air does not get in to the car that is not good. I think I will look at mine.

Answer is YES. An air filter that is loaded up with dirt will reduce air flow, and often causes the engine to run rich, and can be detected by oil analysis thru a low Flashpoint, lowered combustione efficiency, and added wear due to the fuel dilution. Air Filters can become loaded with dirt in as little as 10,000 miles, so it pays to check it at least every other oil change.

For sure! I change my air filter every other oil change. I live in Los Angeles and commutes 3-4 days a week, so you know the filter needs changing!!

When I do (just last week) my mileage went up 2mpg, with nothing different on my part. I think it's worth the cost if you ask me...

Brian

Thanks to everyone for your replies. I have learned my lesson...change the filter every other oil change or so.

Agreed. I live in So Cal and I let my filter go for 11,000 miles... then replaced it and saw an increase of 2 MPG with no other changes. I think I'll change it with every oil change from now on.

Yes, it is really quite possible that you would see that much of an increase after chaning out an obviously dirty air cleaner. But this condition is only valid if there were no other changes to your vehicle, such as changing the air pressure in your tires, etc.

Assuming no other changes in the car (control group) and all you did was change your filter (experiment condition) then the improvement you see is directly related to the air filter.

a post after my own inner science geek's heart! :lol:

jeromep,
Thanks. The airfilter was all I had changed.

Rick

Rick Grahn, do you mind posting the instructions on changing the engine air filter?

I would like to change it myself too.

TIA!

Rick,

Thanks for asking this question. I did not realize how often I should change the engine air filter. I did it once so far at 25K; I am now almost 45K so I should do it again.

I checked my mileage records and the average began climbing after the last engine air filter change. But I did the change in late April, so warmer weather probably helped too.

Maurice

It might be possible to change your air filter once a year, depending on driving conditions. I wish K&N made an air filter for the Prius.

It is odd that they do not, and maybe all you new-prius drivers should make the request to K&N. They do make one for the classic 2001-2003 Prius, and I have used it for about the last 47 k miles. I have cleaned and re-oiled it once, and have "tapped out the bugs" quite a few times. No obvious mpg increase was noted with this filter. My engine oil analyses have not shown high sodium from dirt ingestion, and I think this speaks to one of the major concerns about this filter design.

ScottY,
Well, I am not very mechanically inclined, so if you want a novice's description, you've asked the right person!
1. Buy filter from Toyota (just tell the parts person that you have a 200_ Prius and you want an engine air filter.
2. Open hood.
3. As you face the front of the engine and at about the 10:00 position, you'll see a black cover (about 9" by 14") with three or four clips on the edges.
4. Unclip the clips and lift the cover up.
5. You will see the air filter laying there.
6. Lift the airfilter out and replace it with the new one.
7. Reverse the above (except you do not need to go to the dealer to sell back the old filter )

Again, I am sure it is obvious that I am not a mechanic. If I can do this, anyone can.

Unfortunately, the very fact of stopping and changing the filter can have other unaccounted for control changes. For the Prius, you need 2 cars, driven alongside each other with same tire pressures, same oil fill, same fuel levels, same HVAC settings, etc., except one has a new filter.

ok stupid (that's me) has searched, where is the best place to get, oh lets say, Eng Air Filter, PVC value , ect for my 2004 ... I am sure the dealership parts dept would be very happy to sell/get me some for there $$ price, like they wanted for the oil filter.. (I got 4 with the oil plug crush gasket over the net for about 1/2)

Thanks in advance...

I got a filter at NAPA, but had to cut the plastic frame to make it fit. Notches were missing.

That was maybe 18,000 miles ago, so I'll be looking to do it again relatively soon. Not sure where else to go, since the right part number from other vendors isn't stocked around here...

I think most Toyota dealers sell the air filter for $19 and change. I wait for one to offer a coupon or sale, and generally pick them up for $17 or so. I just changed mine at 15k miles (first time); the old one was fairly dirty, but I saw no appreciable change in MPG. I live near a relatively big city (Minneapolis suburbs) which is probably on the lighter side for airborne crud compared to its peers. I think every 3rd oil change will continue to be my rotation on that.

rpm