Hi folks!

Just a quick reminder to check your engine air filter condition!
I was cleaning my engine bay and decided mehh lets just check my engine air filter and WOW...
Just WOW México is a dirty place (Roads). My Engine Air Filter was horrible, You could barely see any light through it. Luckily its a K&N washable and I have a couple of kits in the garage so I am cleaning it right now.

My specific Air Filter had almost 30K on it so it was overdue to clean in "Severe Conditions" even thought K&N say 50K? Yeah not happening. So that is what I did today to my X...

Have a pleasant Afternoon yall!

 

Good reminder... Actually need to get a K&N drop-in in the next few weeks. Last air filter change was just over a year ago.

 

Just installed it nats and damn! It made a noticeable difference on the mid-top range RPM.
I will have to make a solid reminder to clean this with the Engine Oil change (Every December) because I sincerely thought it could go longer at least the 2 year mark but seems there is more dirt than I thought here in México...

The recharge kit is really handy, I think I am getting around 4-5 cleans out of a single kit now that I know how much is "enough oil".

 

Glad to say I gained around 2-2.5mpgs after cleaning the air filter.. Now sitting at a solid 15mpg city under the same circumstances... I was averaging 11-12mpgs before.

 

Nice!!! Looks like I'll be ordering one next weekend! Thanks have an old recharge kit from several years back for my k&n air filter for my RSX. Used only once, so need to check it out to see if it's still good

 

I dig the aerosol kit more than the liquid oil kit... Easier to apply and you don't go overboard with the oil! I highly recommend it..

 

Good looks! I definitely have the liquid oil kit

 

I've been using K/N drop-in filters for +15 years with my Honda and now Acura. I replace the cabin air filter (Fram CF10134 fits all three vehicles) and clean/spray oil the K/N filter every spring. I haven't had no issues after +382,000 miles between all three vehicles.

 

Have you used the K&N washable cabin air filter mrgold?

 

I really thought about using them; but, at $40 per filter+$15 per cleaning kit X 3 vehicles got a little expensive compared to $10 - $15 each for some of the drop-in types. I figured I would just end up spending a little more money and labor just to break even in 3-5 years with K/N cabin filter. I don't mind spending the extra money and time on the K/N engine filter because max engine performance pays off more compared to max cabin air filtering performance. I would go for the K/N cabin filter if it was 1/2 the cost down the road.

 

How do you explain an improvement in fuel economy; makes no sense.

 

Really?
Clogged filter = Choked engine = Loss in power = Less MPGs?

Seems quite straightforward to me.

 

And it's not like saying I gained HP, I am saying I regained the normal stock engine power..

That dirty was the engine air filter.

 

Yeah the cost benefit ratio also came to mind.. I was thinking perhaps the filter allowed more air flow so I didn't have to set the fan speed higher or something.

 

Ummm, no, it doesn't work that way with modern fuel injected engines. The thing is, modern engines weigh the air in the upper plenum downstream of the air filter and throttle body, and then injects the correct amount of fuel into the engine. It matters not whether half the restriction is from the air filter and the other half is from the throttle butterfly, the intake charge stays the same, and if the air to fuel ratio stays the same the fuel economy will be the same for any given driving dynamic as well.

For an extensive analysis of the above abstract, take a look at this:

• http://www.fueleconomy.gov/feg/pdfs/...02_26_2009.pdf

 

I think of it like how fast and hard can you run if you have to breath from a straw compared to normally from your nose and mouth.

 

Meaning what?

 

@horseshoez, I admire your conviction and dedication toward that crusade but I think it's going to become another one of those controversial topic starters like fuel octane threads. If people want to change their air filters and see a difference, who cares about the reasoning behind it. I say let it go to spare yourself the agonizing debate I can appreciate the looking at it from an engineer's perspective hyper-analyzing everything (I'm the same way) but some things are best left to personal preference

 

I don't have an issue with changing air filters, where I need to challenge folks are the silly, unsubstantiated and physically impossible claims of improvements, even HUGE improvements in fuel economy.

 

You are right, I'm fine with moving on...

 

Humans are fickle creatures. Same logic can be applied to the plethora of ricerbois who feel the need to 'upgrade' to a Cold air Intake system (or WORSE, a Short Ram Intake)


Just let it go, it's not worth the battle

 

MAFs work like that sure, but that isn´t directly proportional to WHY it wastes more fuel.
Even if you have a MAF Sensor calculating the reduction in air flow, ITS PHYSICALLY IMPOSSIBLE (I am a mechanical engineer) for the Engine to produce the same amount of power it was designed to do with less air... You cannot replace air displacement the ECU can only reduce the amount of gasoline it needs to run with a given amount of air, That is not to say you are getting better fuel economy with a clogged air filter.

The example will be like this:
Clean air filter power = 300HP
Clogged air filter power = ~250HP (Add any number here lower than 300HP)
Car weight = 4500lbs on both scenarios.

So if at 300HP a 4500lbs MDX do 17mpgs city.
A 250HP and 4500lbs MDX will do LOWER than 17mpgs city since it lacks power.

You cannot replace POWER when you lower the fuel ratio this means in order to push the same weight you have to depress the gas pedal harder to compensate, This means the engine will live in the higher RPM range for more amounts of time (This is actually proven and tested, Even the ECU calculates for this and hold the gear longer).

So in real world, Not in a lab test.. You do lose MPGs with a clogged air filter, because you have to push the car harder to move at the same rate when its working correctly.

Also I did read the full report, It only seems to care about EMISSIONS and not actual functionality... No wonder as it is for the DOE.

 

But hey horseshoez!
You don´t need to take my word for it... Just grab a clean cloth stick it on top of your air filter (To clog it) and go for a ride.
Then tell us if you gained, sustained or loss MPGs.

 

I never said the engine wouldn't be a bit down on power, what I said was, it is a physical impossibility for a change in fuel economy for any given level of power output. Said another way, the BSFC will not change.

 

If engine is down on power what do you do? keep driving the same or push harder?? in my case is PUSH HARDER thus I felt VTEC Kick In all month long..
Right now the MDX feels like when I bought it, Crisp and fast shifts at 2K will keep me going smoothly to max limit speed, 2 weeks ago I had to go up to 3-3.5K to do the same because the car felt bog down.. Today is a brand new machine, Needless to say WOT feels massively improved.

Right now the MDX is sitting at a 15mpgs full city driving (Which is still far cry of the EPA 17 city btw)...
2 weeks ago I could have shown you 10-11mpgs on the MID screen... It was getting ridiculous, The car felt very different than it does today.

 

Went to my local autozone and got the FRAM "Fresh breeze" cabin air filter (Here in México was just 13dlls! love the exchange rate)
At last! no need to set the fan speed to max to cool me down at 12pm...
But I am still leaning towards the K&N Cabin Air Filter for the air flow.. Saw it on my local Mexican Autozone at 30 bucks! might look into it this december.

 

Did you actually look at the study? As an ME you should have no issue understanding the data presented.

 

The MDX is a strange beast. It has the widest range of possible mpg of any vehicle I've owned or driven in +35 years behind the wheel. I've seen as low as 12-13 mpg in 100% city driving to 25-27 mpg on the hwy later. She is very sensitive to mpgs fluctuation compared to my 06 TSX (27 mpg low to 32-33 mpg high) and 08 RDX (17 mpg low 21-22 mpg high) on the same routes and speeds. It doesn't take much in the MDX to knock down the combined mpgs if internal and external conditions are out of the ordinary.

The MDX might get better mpgs if she had more power under the hood (or drop a few hundred pounds like the 3rd Gen MDX). I live and drive mostly between 5000-8000 feet and the 3.7L does work a little harder, rev a little higher, and shift a little more to maintain the 75-80 mph speed limit around here.

 

Like I said I did read it, Did you?
That study justifies how the ECU and MAF adjust for a decrease in Air Flow..... It DOES NOT account for human behavior and all the tests were done in a Dyno with the same parameters to show there is no decrease in MPGs UNDER THE SAME PARAMETERS.

I repeat once again have you even tried putting a cloth in front of your air filter to test that study??? I have not denied the showings of your study once.... Is easy to quote a study and copy and paste it everywhere but it's harder to understand how it affects real world performance.

I said it does not represent real life scenarios.
IRL if you clog your filter you will lose MPGs as its proven by my very own MDX.

 

 

We are on the same page that gasoline engines waste more fuel in the upper range of the RPM right? Because this is freaking me out. Its like saying I will make the same MPGs at 6800RPM than at Idle.

Clogged filter = choked engine = loss in power.
Less power = More RPM to move the same Mass = More wasted gas..
Its so simple is bizarre we are having a "debate" on dirty engine air filters, I thought this was common knowledge.

 

I think the misunderstanding here is how badly clogged the filter was, I didn´t clean the filter because it had a "slight" hint of dust on it, I never change or clean the K&N because it "Looks dirty" I do not mind about that. But mine had a blob of what it seemed to be dirty engine oil with a thick coat on the bottom that you could scrape it off with a knife, I had to wash the filter 3 times to clean it completely.. If this was a 5-10K filter I would say sure! there is no difference in MPGs (Because it cant, considering the amount of airflow the engine needs on the low end is very little so a 5-10K filter would not be dirty enough to choke the engine)..
But my filter was partially clogged, not dirty, it was affecting performance on the low end. Since this was happening little by little I did not notice the degrade in performance over time, This meant I had to push the engine harder to meet my demands of acceleration.

This is even more noticeable when you see my City vs Hwy MPGs differences..
While my City MPG was plummeting my Hwy mileage was vastly Superior (Given the engine low RPM load at hwy speeds).
Now City mpgs its back where it used to be because the engine works a lot easier to move the 4500lb behemoth, I haven´t seen 3K RPM 2nd gear shift since I cleaned the filter..