What is this 2nd upstream air filter in the Hyundai Air box intake? Pics.

[1 SX]

Quick question, Ive noticed on both of the Hyundais 2009 Elantra and 2013 Sonata, I see a "DO NOT REMOVE" printed on this air box intake secondary filter upstream of the main filter on the lid. So now i'm curious as to why .. Whats is its purpose? Is this just to catch very very fine particles? I cant replace it even if i wanted to because it molded into the top lid of the air box lol. But can i remove it for more air flow? I did a test yesterday with a AEM dry flow drop in, vs regular air filter, and the results are about even, BUT maybe this secondary filter is actually causing a "restriction", as it is upstream the main air filter in the intake.... I'm thinking it EPA related or something, but it just a wild guess.

I'm probably going to leave it, but the curiosity is getting to me on why it has two air filters a replaceable one, and the one that molded into the top lid?
Thanks!

 

[Randol]

IIRC one of my Tacoma's had one of those. I was suspecting it was a charcoal filter to prevent vapors from the intake getting into the atmosphere. Just guessing.

 

[Wrenchturner44]

Looks like it is evap cannister filter. Cannot be serviced, must be replaced.

2013 Hyundai Sonata Vapor Canister Filter. Korea Built Vehicle - 314543R000 | Wholesale Hyundai Parts, Lakeland FL

Vapor Canister Filter. Korea Built Vehicle. Vapor Canister Filter. Included with: Filler pipe. 2013 Hyundai Sonata. Genuine Hyundai Part - 314543R000 (31454 3R000, 31454-3R000,, 314543R000). Ships from Wholesale Hyundai Parts, Lakeland FL

www.wholesalehyundaiparts.com

 

[1 SX]

IIRC one of my Tacoma's had one of those. I was suspecting it was a charcoal filter to prevent vapors from the intake getting into the atmosphere. Just guessing.

Wow! You would be right!. A google search later on "intake Charcoal Filter Hyundai" and this page pops up https://www.gencoupe.com/threads/diy-carbon-filter-removal.91767/ Seems people actually REMOVE it for more air flow. Its strictly there for the reason you stated, about gas vapors when the engine is shut off, and no other reason, it also does create a restriction in air flow.... because the engine has now two filters. Some people posted that they got up to 1+MPG better fuel mileage, better throttle response down low, and more WOT power after removal... I think its believable if it as restrictive as they say.

Maybe i'll remove it, test the readings on airflow, and go from there.

 

[1 SX]

Wow, So i went ahead and removed it without breaking it, and the numbers... dont lie!. It WAS causing a restriction in the intake of air flow. Even at idle with AEM dryflow installed and at 654rpms, MAF now reads 0.4lb/min vs 0.3lb/min @ 660 rpms with the carbon filter installed and AEM dryflow drop in.. At WOT its an even bigger difference!. Yesterday at WOT and a 6154rpm shift with the AEM drop in, it never went above 13.8-14.0lb/min, now today with the carbon filter removed, at WOT and 6148rpm shift it went all the way to 15.7lb/min.

Carbon Filter removed, looking at sunlight.

Idle reading 654 rpms with carbon filter removed and AEM dryflow drop in.

Idle reading 660rpms with carbon filter installed, and a wot run. MAF reading 0.3lb/min idle max 14.0lb/min

And here is idle 652rpms maf reading 0.4lb/min wot 6148rpm shift 15.7 lb/min with carbon filter removed with AEM dryflow drop in..

Im going to keep it removed, and see if gas mileage increases a little. It does feel slightly more eager to rev, and feels like it pulls slightly better down low..... Also i did not smell gas or anything when i turned off the engine.

 

[Mainia]

I don't have one of those on my 2018 Hyundai Kona AWD 1.6T. It would be long gone if I did though. Nore do I remember one on my wife's 2013 Elantra GT. Is your car a California car?

 

[OVERKILL]

Wow, So i went ahead and removed it without breaking it, and the numbers... dont lie!. It WAS causing a restriction in the intake of air flow. Even at idle with AEM dryflow installed and at 654rpms, MAF now reads 0.4lb/min vs 0.3lb/min @ 660 rpms with the carbon filter installed and AEM dryflow drop in.. At WOT its an even bigger difference!. Yesterday at WOT and a 6154rpm shift with the AEM drop in, it never went above 13.8-14.0lb/min, now today with the carbon filter removed, at WOT and 6148rpm shift it went all the way to 15.7lb/min.

Carbon Filter removed, looking at sunlight.
View attachment 72417

Idle reading 654 rpms with carbon filter removed and AEM dryflow drop in.View attachment 72418
Idle reading 660rpms with carbon filter installed, and a wot run. MAF reading 0.3lb/min idle max 14.0lb/min
View attachment 72420

And here is idle 652rpms maf reading 0.4lb/min wot 6148rpm shift 15.7 lb/min with carbon filter removed with AEM dryflow drop in..
View attachment 72421


Im going to keep it removed, and see if gas mileage increases a little. It does feel slightly more eager to rev, and feels like it pulls slightly better down low..... Also i did not smell gas or anything when i turned off the engine.

Do you still have the old filter to try and see if it remains the same as well?

Also, not sure how the MAF is positioned on this engine but the turbulence/flow profile of the air may change with that secondary filter removed, which make have an impact on these readings.

We used to have to "clock" the MAF's sometimes in the EEC-IV cars with the aftermarket CAI's because of the impact they'd have on airflow.

 

[1 SX]

I don't have one of those on my 2018 Hyundai Kona AWD 1.6T. It would be long gone if I did though. Nore do I remember one on my wife's 2013 Elantra GT. Is your car a California car?

I believe it is CA/NY emissions.

Do you still have the old filter to try and see if it remains the same as well?

Also, not sure how the MAF is positioned on this engine but the turbulence/flow profile of the air may change with that secondary filter removed, which make have an impact on these readings.

We used to have to "clock" the MAF's sometimes in the EEC-IV cars with the aftermarket CAI's because of the impact they'd have on airflow.

The MAF is on the intake, here is a pic of the MAF location. I think it has a baffle on the top lid to prevent flow/turbulence problems. It runs smooth, so i dont think there are any flow problems, and MAF readings look good with no abnormal jumps or spikes.

 

[researcher]

Wow, So i went ahead and removed it without breaking it, and the numbers... dont lie!. It WAS causing a restriction in the intake of air flow. Even at idle with AEM dryflow installed and at 654rpms, MAF now reads 0.4lb/min vs 0.3lb/min @ 660 rpms with the carbon filter installed and AEM dryflow drop in.. At WOT its an even bigger difference!. Yesterday at WOT and a 6154rpm shift with the AEM drop in, it never went above 13.8-14.0lb/min, now today with the carbon filter removed, at WOT and 6148rpm shift it went all the way to 15.7lb/min.

Carbon Filter removed, looking at sunlight.
View attachment 72417

Idle reading 654 rpms with carbon filter removed and AEM dryflow drop in.View attachment 72418
Idle reading 660rpms with carbon filter installed, and a wot run. MAF reading 0.3lb/min idle max 14.0lb/min
View attachment 72420

And here is idle 652rpms maf reading 0.4lb/min wot 6148rpm shift 15.7 lb/min with carbon filter removed with AEM dryflow drop in..
View attachment 72421


Im going to keep it removed, and see if gas mileage increases a little. It does feel slightly more eager to rev, and feels like it pulls slightly better down low..... Also i did not smell gas or anything when i turned off the engine.

My 06 Scion tC had that in the air intake, right above the main engine air filter. You are 100% correct it was for some emissions in case vapors made their way back through the air intake hose. No one could ever find the EPA rule for that thought, I never did.. Mine got completely blocked/clogged up and no replacement was available, you had to replace the entire air filter lid.. NO THANKS! Removing it, since of course it was a blockage, the engine could breathe again! mpg's went up about 2-3, seriously! Now there is a nice throaty burble to the intake (not bad for basically a Camry engine).. So good for you to remove that. Sure I might get some "environmentalists" telling me how I'm killing the planet because I removed this filter, but that's too funny.

As you saw you never smelled any gas vapors, neither did I. EVER!

One more thing.. When I did my research on it, I ended up on a BMW forum, about the 5-series engine. In Europe they never had that secondary emissions filter, but the US-destined engines did. And I'm in Michigan, if it were for CA/NY emissions, guess we all had to get that? It's gone now..

 

[NitroM3]

The MAF measures the flow so unless you change the % of throttle it makes no sense the need to change the clock position of the sensor. CAI in most applications while they may increase a total amount of CFM available most so called CAI are not true cold air intakes which has some interesting effects on the ECU unless corrected and you can’t add more cfm to an engine which is the mechanical formula of the engine size but you can if carefully planned out reduce the cfm restrictions in an intake filtering system.

 

[OilMagnate]

Well, I actually learned something here. Interesting!

 

[OVERKILL]

I believe it is CA/NY emissions.


The MAF is on the intake, here is a pic of the MAF location. I think it has a baffle on the top lid to prevent flow/turbulence problems. It runs smooth, so i dont think there are any flow problems, and MAF readings look good with no abnormal jumps or spikes.

OK, so the MAF is close to where that 2nd filter was (which is what I was suspecting) which COULD potentially have a small impact on measured flow, depending on how things look between where that 2nd filter was and the MAF but the OEM plumbing is typically pretty good in this regard.

You could have used a restriction gauge in the top of the airbox to measure before/after, which would have been interesting.

 

[OVERKILL]

The MAF measures the flow so unless you change the % of throttle it makes no sense the need to change the clock position of the sensor. CAI in most applications while they may increase a total amount of CFM available most so called CAI are not true cold air intakes which has some interesting effects on the ECU unless corrected and you can’t add more cfm to an engine which is the mechanical formula of the engine size but you can if carefully planned out reduce the cfm restrictions in an intake filtering system.

The Clocking of the MAF was due to the elbows the aftermarket CAI's had that had an impact on measured airflow (think of the effect a curve has on velocity) which would cause surging (which EEC-IV was notorious for). Rotating the MAF on these CAI's, moving them more outward on the curve or further in on the curve would eliminate it. The actual amount of air ingested doesn't change, it's how the sensor is exposed to the airstream that impacts what the sensor "sees".

So yes, the location of the MAF in the airstream can have an impact depending on what the intake design looks like. A super fun one was guys that did the warm air intakes (they were "CAI's" but of course didn't suck in cold air) with the big cone right below the MAF. Fan wash would cause all kinds of fun with the metered air reading and caused drivability issues.

 

[NitroM3]

I guess that was a poorly designed CAI.

 

[NitroM3]

OK, so the MAF is close to where that 2nd filter was (which is what I was suspecting) which COULD potentially have a small impact on measured flow, depending on how things look between where that 2nd filter was and the MAF but the OEM plumbing is typically pretty good in this regard.

You could have used a restriction gauge in the top of the airbox to measure before/after, which would have been interesting.

This is so guessing without data logging at different engine speeds ... several PIDs .And I would say based on calibrating ECU for inductive system improvements on enough different platforms to say rare at best. But nice posting.

 

[OVERKILL]

I guess that was a poorly designed CAI.

Yep, absolutely, but a lot of them are. Just something to be aware of, as it does happen.

 

[NitroM3]

Yep, absolutely, but a lot of them are. Just something to be aware of

Overkill I fell off my chair...dude we agree on something

 

[OVERKILL]

This is so guessing without data logging at different engine speeds ... several PIDs .And I would say based on calibrating ECU for inductive system improvements on enough different platforms to say rare at best. But nice posting.

Absolutely, and I wasn't implying this was in fact happening in his case, just pointing out that metered air can be impacted by how the MAF "sees" the airstream. The amount of air the engine ingests at idle under the same conditions shouldn't really change going from one filter to another. If the secondary filter was indeed restrictive, that restriction would become increasingly evident as load and engine speed increased.

What caused me to raise an eyebrow was the air mass idle reading, which shouldn't have changed with the TB being the biggest restriction in the system which is why I tossed that out there. This is where vacuum measured in front of the MAF using a restriction gauge or sensitive vacuum gauge would be helpful in determining if restriction did in fact change or if we are just seeing an artifact of the airstream changing due to the elimination of the secondary filter.

 

[NitroM3]

Since composite intakes have now become the norm over aluminum they make for new challenges and most are how intrusive they are to the air flow. While a direct port engine is not as effected at lower engine speeds wot with a stock composite on many applications has a flow meter acting like a tach registering a mis shift with all the turbulence prior the intake port on the head at very high engine speeds. Never the less your info I have filed it as good info in the event I have a MAF that seems to be fighting a ECU calibration I change in the future. What you said does make sense.
The biggest problem I find with most CAI is inconsistent IATs. That could fill a few response of discussion on a thread all its own. Ha! If you even suggest that for a Dailey driver or seldom performance run engine that the the OEM airbox is likely better to stay with in most cases is setting yourself up for “you don’t know what your talking about” responses. Lol

 

[OVERKILL]

Since composite intakes have now become the norm over aluminum they make for new challenges and most are how intrusive they are to the air flow. While a direct port engine is not as effected at lower engine speeds wot with a stock composite on many applications has a flow meter acting like a tach registering a mis shift with all the turbulence prior the intake port on the head at very high engine speeds. Never the less your info I have filed it as good info in the event I have a MAF that seems to be fighting a ECU calibration I change in the future. What you said does make sense.
The biggest problem I find with most CAI is inconsistent IATs. That could fill a few response of discussion on a thread all its own. Ha! If you even suggest that for a Dailey driver or seldom performance run engine that the the OEM airbox is likely better to stay with in most cases is setting yourself up for “you don’t know what your talking about” responses. Lol

Whoa, another thing we agree on! LOL!