DIY: Secondary Air Filter Removal

I have the 07 2.7L I4.

If you follow the path of air from the beginning of the intake to the engine, the sequence of filters is:

1. Outside air entry
2. Charcoal filter
3. Paper filter
4. Engine

Take the air filter cover off and look underneath it. It'll be a plastic mesh covered charcoal filter. Resting in the bottom of the airbox is the paper filter.

I experimented with my gas mileage by just removing the paper filter and only leaving in the charcoal filter.

According to my Scangauge II, my gallons per hour dropped from 2.5 gph to under 1.8 gph for the same speed under cruise control.

To be sure, I'm going take a 330 mile trip @ 70 mph with this configuration. My best mpg with stock configurations is 27.6.

I hoping the test configuration (charcoal filter only) will net over 29.0 mpg.

I'll keep you guys posted.

 

It's BAD for your engine to run it without the paper filter!!! That's what keeps all the dust and grit out of your engine! The secondary filter won't filter the small particals.

 

Absolutely no disrespect intended, but I'm not thinking this is going to be a good idea! The charcoal filter is not designed to filter air going into your engine, much less protect your engine from small debris. The charcoal filter is designed to protect the environment from post combustion gasses in your engine after shut off.

You have shown me some pretty impressive equation that proved your points in the past, so if I am wrong, then I'd like to see and know why, but as of now I strongly urge you to re-consider running the truck with only the charcoal filter.

Regards,

 

No disrespect taken . I'm way ahead of you. I agree 100%. This is only a 1 trip scenario. I made a 110 mile trip tonight and averaged 29.9 mpg as opposed to the 27.6 norm.

Normally the gph was 2.60 but I was seeing consistent 2.04's and even 1.75's when I drafted a semi-trailer @ 60-65 mph.

Mostly I just wanted to see if buying an aftermarket (low restriction non-oiled) drop-in air filter would be beneficial down the road.

I will note that idle was better and so was accelleration.

The paper filter got replaced tonight. The only real reason I'm not too concerned about foreign matter entering the intake during this test is that the ground is still wet and not very much dust has been in the atmosphere lately.

Bottom line...the mpg went up noticeably. 27.6-29.9 = 2.3 highway mpg difference. Rounded off the .3 to only 2.0 is still great in my book.

By the way, drafting was showing 1.6 - 1.75 gph and mid to upper 30 mpg (34-37.6) and this was 30 feet trailing a semi @ 60 mph. I actually saw it go over 41 for a short time when I got boxed in from behind with a Suburban about 20 feet to my rear. I would classify that scenario as a "draft train" .

Anyways, I had a big-ass smile on my face.

 

Pulled the filter out today in a parking lot. It was that easy. I just cut the studs and popped it free and put it someplace safe.

I could tell it idles better now and the acceleration on the freeway (over 3000 rpm) is much better. I was surprised that I could tell a difference. I did it just to get better MPG.

So why is trapping a little fuel vapor when the vehicle sits better than getting the 2+ mpg improvement? Better MPG will result in less fuel being used overall, rather than the small amount that can now creep out of my engine.

 

I did this just a few minutes ago with a screw driver, just popped the tops off and pulled it out. I normally make 19 mpg city driving and 21hwy, with my v6 4dr 4x4. It will take me a while to get new results, I live in a small town 2 miles to town and back. I also work offshore for long periods of time. I have owned my truck for some 9 or 10 months and only have 7000 miles. Should last forever like this.

 

So I finally removed the secondary filter a couple weeks ago. I removed it just before leaving on a road trip and closely monitored my gas mileage. Needless to say I was instantly surprised with the effect. My trip was 300km one way, and when I reached my destination I noticed that my fuel gauge was just on the half full mark - normally I averaged 240-250km at the half mark. However, after filling up and calculating my mileage I was upset to see that my mileage had not changed at all - I was still stuck at the 16MPG mark. My mileage was also the same on my trip back to Calgary.

 

I just got back from a 650 mile trip up north to San Luis Obispo. I was helping my sister move and on the way there I was loaded to the brim in back, guessing 600-800lbs, plus a passenger. I was expecting to get horrible mileage. I got 27.3 MPG on the way there, fully loaded. I think that this is proof that removing the secondary filter on the I-4
is worth while.

 

Thanks for the post. I just removed mine from my
2006 4 cyl. and it seems to have better throttle response and
it was as if it's allowed to "breathe,"

 

I will be doing this all over again next week when I get my 2008 Tacoma 4.0L!

 

I have the 2.7 4cyl '05 4x4 tacoma manual 5 speed, and i notice a huge differnt in 1st-3rd gear, hitting higher speeds befor redlining, befor i would have to shift outta 3rd to 4th at about 50km/h(30mph) to keep shits befor 3000 rpm now i dont throw it into 4th untill im doin about 65-70kmh, also i can get up to 100 in second befor i redline at 5200 roughly! also notice a hugh difference in back pressure, overall my engine and my foot have been lovin it! Note i used to own a 5.4 triton f150, and my taco would kill it in a quarter mile!

 

It makes no sense that you would be able to achieve higher speeds before redlining by removing intake restriction, removing you secondary air filter will not magically regear you truck.

Now you might rev faster to redline but you top speed in each gear would remain the same (except you might gain a higher top vehicle speed in 5th gear, of course the governor will prevent you from finding that out.

 

i just removed mine. did it with a soldering gun and a curved dentist pick. just melted the 6 nubs and pulled with the dentist pick. if need to replace just put the filter back in and touch up with the soldering iron! ya thats the ticket

 

Good idea, I'll be doing that this weekend.

 

Here is my only issue with removing the second filter. I think it would be a great idea, and will consider doing this.. But this is what happened to me. a few months ago my wife took the truck in for an oil change where they opened the air box up to check the air filter. I have a K&N filter (with the "STOP do not OPEN" sticker on the box), but some A-Hole at the oil place opened the box to check the filter anyway... No big deal right??? Problem is: that guy did not put the filter back in correctly, and did not secure the box correctly.. The box had about a 1/3 inch opening on the bottom (where it was not easy to see).. So it sucked in crap for I dont know how long. If that second filter was not there, it would have been worse...
If you do take the filter out... Make sure that someone (besides you) does not open it up and cannot close it correctly.
Not to say that this filter helped me, but it was better than no filter at all.

P.S. I do all my own oil changes now.....

 

Unless you were sucking in 2x4's I don't think the secondary filter would do shit.

 

Your problem was that your wife took it in to get serviced instead of you doing it. The other problem is that she took it to the nearest high school
dropout that can't read. He probably aired up your hot tires to 45 psi too, right after he overfilled your brake fluid (that wasn't low) and I bet he put some no-name cheap oil filter in along with the cheapest drum oil the shop could get.

My truck gets serviced by me and only me. I know from past experience with other vehicles just what can be done to a car in short order. Do you think that the folks working at jiffy-screw are very bright? They guys making just over minimum wage because they remember which way to turn a wrench (most days)

 

Agree with both posts....

Min wage jobs attract min wage service.

Wife is no longer able to take to get ANY service.

I do all my own oil changes....

 

Hope I didn't come off too bluntly. My GF took her car to a dealer to get an estimate on brakes, they said $700, more if they find problems. To prove to her that she was getting taken advantage of I took her car to another dealer and they told me $300. I took the estimate and on the way back bought the stuff to do it myself...$50 and 2 hours later she had her brakes done. It would have been more had the rotors needed turning, but not $250 more. So, my point is two fold, maintenance is the man's job (unless the wife likes doing it) and most mechanics only charge women and ignorant men for topping off the blinker fluid.

 

Been following this thread for awhile and there seems to be enough evidence of MPG improvements even in the V6 by removing the secondary air filter so I removed mine today. I undid the 2 clips, opened the air box and then used a Dremel and just ground the heads off the plastic rivets and the filter came out in 2 minutes. Used a shop vac to clean up any plastic shavings and wiped the air box down.

I only have 3 tanks of gas through the truck but only getting about 16 MPG with sometime having it in 4 wheel drive. Also did the mod to disconnect the AC from the defroster. The AC only comes on when the button is pushed.

Hunting for the elusive MPGs. Thanks for the post and all the ideas.