Engine Air filter.. Does pre filter reduce mileage efficiency?

Hey Folks,
Currently have a FRAM paper filter with a prefilter. Wonder if this prefilter restricts air causing drop in mileage.? From reading i gather its helps prevent the actual filter be clean a longer time, helps also to stay dry during snow/winter/rain conditions. I am seeing only 21L/100 in mine, not sure whether to trust the guage. Have had all fluids replaced incl tranny oil, greased the joints. Spark plugs are due for a change soon. Truck has 174k kms. Your thoughts appreciated.

 

The foam is for cold weather, won't hurt to remove it. Unlikely you'll notice much different TBH.

 

There is no reason to use a product just to keep the air filter cleaner for longer. Might as well just replace it more often in that case

 

oem doesn't have the foam glued on filter. who called it a pre filter. which there is no such thing. i always purchase a toyota filter, you can find at a discount.

 

Toyota use to us a prefilter on the Tundra but have since removed it.

 

Unless Fram sells the "prefilter" separately so it can be changed without changing the entire filter, then it isn't a prefilter...it's just an added layer of filtration. It makes you wonder if their filter design didn't perform to expectations, and they had to "enhance" the design with a "prefilter".

But your question was whether the prefilter reduces gas mileage. It's impossible to answer that without knowing how much pressure drop Fram has designed across the entire filter. If the Fram filter has more pressure drop than the OEM filter, fuel efficiency will possibly be reduced.

Dirty air filters (high pressure drop) allegedly cause reduced fuel efficiency in these fluff articles written by the automotively challenged on how to increase your mileage. Frankly, I've never observed any change in mileage with new filters...maybe I haven't let them get dirty enough.

 

I definititely have. as much as 5-10% !!!

I don't let them get that dirty any more.

 

I wouldn't be buying Fram anything. They are not known for their quality.

 

Pretty much everything FRAM makes is as useful as a screen door on a submarine.

Go OEM, Wix, Donaldson etc... I’d stick a properly oiled K&N in there before a FRAM filter.

Just sayin’

 

I'd stick in a properly oiled reusable K&N before any of those....been using K&N's for 48 years now and counting. Never had an issue. Never. Just sayin

 

Me too. What I run. Just didn’t wanna rile up those that love the Youtube “flour” tests

 

I use K&N primarily for the reusable factor. There is a bit more air flow than stock which can't hurt but I never noticed any more power and never expected to despite K&N's claims.

 

Wix uses a pre filter just had a new one show up at the house

 

Thanks folks, Sure will move to KN soon, truck came with the FRAM which looks really new. Just did a seafoam on the intake vacuum port & now i see a good almost 3.5L /100 increase in mileage. I do have a KN CAI off a F150 (5.4L eng)laying around perhaps can try it out.

 

Make sure you do not over oil a K& N. If you do you will get a CEL and your mass air flow sensor will be gunked up

 

Not rocket science. Never had a fouled MAF. Follow the simple instructions when re-oiling. Just sayin. See pics on my build thread when I went to check my 07 MAF. Clean as a whistle after 5 years. Like I mentioned I've been using K&N's since 1972 with zero issues.

 

That increased airflow that "can't hurt" is also letting significantly more dirt into your engine.

Stick to the OE stuff

 

Bull Shit......Couldn't disagree more. It's a very small air flow increase and only has an affect at higher rpms and the so called HP gains anyways. Do your homework. The thin layer of oil adds a spider web effect to "prevent" even smaller nano particulates getting through. Millions of K&N users must be wrong all these years? aFe makes an oiled version drop in with increased air flow claims. Is aFe wrong too? I guess using K&N's for 48+ years with zero issues was a fluke? Get real.

 

Wow

 

True! The Wix has that foam layer too.

 

One of my rare OCD responses, and I'm not the overly OCD type. Especially at my age. The oil adds an additional layer of protection. Yes, you can over oil but you only need to lightly spray a very thin film of the oil. CRC makes a wonderful MAF cleaner. I've been wasting my $ using it. Every 6 months or so I spend maybe 10 minutes taking out the two screws to remove the MAF. Inspect. Still clean. I spray CRC cleaner on the MAF anyways. Let it air dry for a couple minutes and re install. 10 freaking minutes.

At the same time I use CRC throttle body cleaner. To take off the TB takes likes 5 minutes. Inlet is usually clean. The opposite side can get carbon buildup. That's what you look for. If there is significant carbon buildup>>>>change out your PCV. $5 and another 10 minutes.

 

LOL, the only filter that doesn’t let dust through is oem. Tried them all and K&N is the worst. But that’s desert use, maybe fine elsewhere.The foam layer on the Wix filter is a hydrophobic filter, probably same on Fram so maybe nothing to do with filtering air

 

@Black Wolf , because I like 'ya, I going to post this link. Sounds like you're sold on them, so you're probably going to want to kill the messenger, but read @dragos28 experience with K&N for yourself. I am sure it is unlikely to change your mind, but read for yourself. I had decided long before that K&N was not for me.

https://www.tundratalk.net/threads/major-dust-intake.570858/#post-7136170

 

Not killing the messenger. Of course I'm sold on K&N after almost a half century of using. Even on my dirt bikes back in the day. I've wheeled on the Mohave, Black Rock Desert in Nevada, nothing worse than alkali silt. Kills filters. Even the best. Gets into everything. Down to San Luis in Baja back in 76. Went to several early SCORE events. Got side tracked by the Marine Corps for a bit. Things happen but "millions" of K&N users have had great results over the years. I used to 4 wheel a lot in Winchester Bay, Orygun sand dunes. The "Collosium" . Now closed off. Never had fine sand get by my K&N then and not fine dirt silt south of Ensenada. Some folks have issues. You are right, but 48 years without issues isn't going to change my mind at all.

 

To be fair...That thread is just as likely to show user error. Unless I read it wrong the OP modified the airbox and didnt even look like it sat flush in pics.

 

Exactly. Modified the airbox with a bad seal and then complains about the filter not doing its job and TundraTalk sucks somewhat nowadays. Been going down hill for some reason....... I heard some other Tundra forum "ahem" is much better...heh...heh...

 

That's better and well explained. Everyone has their moments.

 

Yeah, I have mine...heh...heh..

 

It' legal in your state.....just saying.

 

Not my cup of tea...heh...heh..