Air Filter Box Contraption

[rocky-mountain]

I opened my air filter box to inspect my filter and noticed inside the plastic box a strange looking flap type device which is held closed by a light magnet. What is the point of this thing? Can I expect to see a slight improvement in acceleration if I remove this flap?

 

[cane2025]

Any pics? Could it be a sensor of some kind?

 

[Alwaysforward]

I think I remember reading that previous Gen owners removed this flap to gain engine performance. It would most likely void any warranty coverage if anything happens to the engine.

 

[Gunkk]

I opened my air filter box to inspect my filter and noticed inside the plastic box a strange looking flap type device which is held closed by a light magnet. What is the point of this thing? Can I expect to see a slight improvement in acceleration if I remove this flap?

This thread explains it's function:

http://genesisowners.com/hyundai-genesis-forum/showthread.php?t=14917


Here's the original Gen 1 thread showing the throttle response mod:

http://genesisowners.com/hyundai-genesis-forum/showthread.php?t=13828

 

[rocky-mountain]

I read the other thread concerning the flap and everyone who removed it immediately noticed stronger acceleration and better throttle response. Today I removed the flap and took it for a drive and there is definitely a noticeable improvement in acceleration.
The flap is held down by a magnet and it takes a minimum of 4000 rpm of suction to overpower the magnet and lift the flap open according to a guy who actually tested this. I still have no idea why Hyundai installed this power robbing contraption. I also noticed that my car is idling a little smoother and in terms of drivability, aside from the extra bit of power, everything is fine.

 

[Schindawg]

I read the other thread concerning the flap and everyone who removed it immediately noticed stronger acceleration and better throttle response. Today I removed the flap and took it for a drive and there is definitely a noticeable improvement in acceleration.
The flap is held down by a magnet and it takes a minimum of 4000 rpm of suction to overpower the magnet and lift the flap open according to a guy who actually tested this. I still have no idea why Hyundai installed this power robbing contraption. I also noticed that my car is idling a little smoother and in terms of drivability, aside from the extra bit of power, everything is fine.

Rocky - how did you completely remove the flapper door? Mine looks riveted on. I did remove the magnet on the flapper and that has noticeably improved throttle response from a stop. I was never quite happy with the dead pedal feel.

 

[Top Gear]

Ah, there is a similar free mod for the 3.8 Coupes in the US. At least some of the models have a "carbon" filter above and after the regular paper filter. It's per the EPA to prevent fumes coming back out in the rare event you experience a backfire, etc. I'm sure this flap is the same idea, just a different solution.

On the 3.8 Coupes, the stock paper filter is the equivalent of a K&N hi-flow, because it has to accommodate that other carbon filter. So, removing the carbon filter makes a dramatic change in CAI growl, low-end grunt, and overall performance, easily 10-20 HP depending on this or that. It's very unlikely the dealer mechanics will notice it's gone, on the Coupe, anyway. Looks like the pics in the thread linked above show that removing this flap will also go unnoticed, and that the airflow without it will be very beneficial Is there a secondary carbon filter as well? Remove it.

Oh, and I've had this removed for some 20k miles and there are no issues. The computer will retune the engine to take advantage, as well. Run some premium gas from one of the best brands so that you're getting the most out of it, which will also trigger the ECU to tune the engine for better performance and mileage.

Hope that helps!

 

[DRS]

I read the other thread concerning the flap and everyone who removed it immediately noticed stronger acceleration and better throttle response. Today I removed the flap and took it for a drive and there is definitely a noticeable improvement in acceleration.
The flap is held down by a magnet and it takes a minimum of 4000 rpm of suction to overpower the magnet and lift the flap open according to a guy who actually tested this. I still have no idea why Hyundai installed this power robbing contraption. I also noticed that my car is idling a little smoother and in terms of drivability, aside from the extra bit of power, everything is fine.

I have not dug deep in the hood.. Does the piping that flapper is attached to get routed to the front of the car? Or is it an opening right in the engine bay? Seems like there is some confusion about this. Some have claimed the flapper area draws in hot air from the engine bay.. So, their theory was, it can draw in too much warm air verses the air duct system that comes over the top of the grill (in normal driving conditions or in town.. That it hurts more than helps when under hood temps are hot to have the flapper removed.... Let me know what you see... If the piping where you have removed the flapper is run to the front of the car and gets cool air, that would be perfect.. Thanks for initial feedback how it is working.

I saw the video the person posted with the light bulb testing system to see when the flap opened (broke contact). Proved it does stay closed for a long time and could cause the hesitation many feel off the line.

 

[PaFromFL]

I wonder if the stronger acceleration comes at the expense of gas mileage. Maybe the flap is way to meet EPA goals without reducing wide open throttle performance.

 

[Top Gear]

My mileage has been better with the carbon filter removed. Allowing the engine to breath better and letting the ECU get more out of it for every throttle position is good for performance as well as overall mileage, in this case.

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[DRS]

My mileage has been better with the carbon filter removed. Allowing the engine to breath better and letting the ECU get more out of it for every throttle position is good for performance as well as overall mileage, in this case.

In the sedan, V8, if the air behind the flapper, comes direct from inside engine bay, warm/hot air, could affect mileage and in town sluggishness. If it is plumbed to get colder air in front of radiator, should think it would be better.. There are others who put it back in, and then used gorilla tape on the magnets to weaken them.. Therefore it opens sooner.. But is closed off in part throttle.. They seem to like that.. The posts are in the sedan area that cover all this.. I think I will figure out if it is cold air or not, and make some kind of mod here over the weekend. Get off my butt and see for myself.

 

[DRS]

👆👆👆👆👆 Oops... Meant to reply to PaFromFL...

 

[Top Gear]

Oops, as a Couper, I did in a Sedan thread what I hate Sedaners do in Coupe threads So, I did some digging and remembered past discussions. Yes, this flap appears to be a stop-gap way to get more out of a restrictive CAI at high revs when you stomp it. IMHO, I'd either leave it alone or permanently open it if I could install some ducting to at least pull colder air. I see why this is frustrating. However, to those who argue that CAI mods are just more noise and no HP, this flap, just being there, proves otherwise

As for the Coupes, we have such a great stock CAI it's hard or impossible to best with aftermarket bling. Most modders put on an SRI to look cool, but as an "HAI" it's actually worse than the stock CAI. Also, there's the carbon filter with a stock hi-flow paper filter. Thus it's a brilliant simplicity to remove that second filter and have one of the best CAIs around. My intake temps (via the ECU) are usually only a few degrees different from outside temp.

It looks like the Sedans, at least some models, also have this secondary EPA filter right next to the paper one, and so you can also easily remove it, too. This means such a Sedan's paper filter is also hi-flow (which is why only dropping in a K&N does nothing in such cases).

 

[DavidA5913]

Top Gear: Can you please point us to any pictures of the second carbon filter you refer to? That would help this novice. Thank you.

 

[DRS]

Oops, as a Couper, I did in a Sedan thread what I hate Sedaners do in Coupe threads So, I did some digging and remembered past discussions. Yes, this flap appears to be a stop-gap way to get more out of a restrictive CAI at high revs when you stomp it. IMHO, I'd either leave it alone or permanently open it if I could install some ducting to at least pull colder air. I see why this is frustrating. However, to those who argue that CAI mods are just more noise and no HP, this flap, just being there, proves otherwise

As for the Coupes, we have such a great stock CAI it's hard or impossible to best with aftermarket bling. Most modders put on an SRI to look cool, but as an "HAI" it's actually worse than the stock CAI. Also, there's the carbon filter with a stock hi-flow paper filter. Thus it's a brilliant simplicity to remove that second filter and have one of the best CAIs around. My intake temps (via the ECU) are usually only a few degrees different from outside temp.

It looks like the Sedans, at least some models, also have this secondary EPA filter right next to the paper one, and so you can also easily remove it, too. This means such a Sedan's paper filter is also hi-flow (which is why only dropping in a K&N does nothing in such cases).

Thanks for the thoughts.. Heading out to DRS garage to examine both 2012 5.0 ans 2015 5.0. Will try to get some clear pics.

 

[amartz]

I wonder if the stronger acceleration comes at the expense of gas mileage. Maybe the flap is way to meet EPA goals without reducing wide open throttle performance.

For those of us that have made a modification, it was never about WOT performance. It was about getting rid of the lag, usually at a rolling stop, when you first step on the throttle. A lag that many blame on transmission programming, but is really due to the engine not quickly building rpms, because it can't breath.

 

[DRS]

For those of us that have made a modification, it was never about WOT performance. It was about getting rid of the lag, usually at a rolling stop, when you first step on the throttle. A lag that many blame on transmission programming, but is really due to the engine not quickly building rpms, because it can't breath.

Yep. Agreed.. Did the gorilla tape thing today.. Decided not to take completely out.. Test this first and see the difference between this mod and the door being taken out. The piping does terminate just beside the radiator behind the lights. Got pics of that.. Found debris in the piping..so, must have some colder non under hood air pressure while moving.. And some heat soak blocked by the piping. Also, the felt lining on the piping to make quieter also collects dirt and debris that stick to it..


I would expect those the remove the flapper completely will get more dirt and debris in the air box pre filter.. But who cares?

Decided to punt in taking the structure braces out in order to get the dual air box open on the 2015. Do not know if they have carbon pre filter in there along with filter. The 2012 does not. The 2015 looks much more free breathing.. But looks can deceive.

 

[Top Gear]

Sorry, David, I don't have pics of the Sedan versions, so Google it, or inspect your car.

Since these filters are mandated by the EPA, every normally aspirated car sold in the US should have one made during the last many years (the turbo Coupes do not have them, I'm told). This carbon filter should be post-hi-flow-paper filter, and usually they are right next to each other. Together they make one regular paper filter's flow rate. On the Coupe, the paper filter is in the lower portion of the airbox, easy to see when you pop the clips to change it, but the carbon one is in the upper portion of the airbox, thus you can't see it when you lift it to change the paper filter, unless you get down low with a light. Perhaps the Sedan is the same way. You'll probably have to disassemble some things to get the airbox out so you can remove this filter. Be sure to remove it so that it can be put back in if you want. Chances are, though, you'll never need it ever again.

For those of us that have made a modification, it was never about WOT performance. It was about getting rid of the lag, usually at a rolling stop, when you first step on the throttle. A lag that many blame on transmission programming, but is really due to the engine not quickly building rpms, because it can't breath.

I agree. If I'm right, though, you can have the same benefits removing the EPA carbon filter. On mine, it resulted in incredible throttle response and low-end torque over stock.

 

[jarred52]

Has anyone taken out the structure base to get to the air filter in the 2015 V6? Were there any problems in doing this? Does the system have the magnet talked about in this thread?

Thanks!

 

[Schindawg]

Has anyone taken out the structure base to get to the air filter in the 2015 V6? Were there any problems in doing this? Does the system have the magnet talked about in this thread?

Thanks!

Yes, the 2015 V6 has the magnet in the flapper door. It's very easy to get too. Simply remove the structural brace over the air filter housing, flip open the snaps to reveal the paper air filter element, and remove the air filter. The flapper door mechanism is directly under the air filter element. So far I have only removed the magnet from the flapper door. Easy to do with a small flat bladed screw driver. I'm contemplating removing the door completely as I have already seen better throttle response from a stop, and at low speed. I have not seen any carbon filter that's being talked about. Air being fed into this box is where DRS posted earlier, coming from behind the radiator, so it is not hot air from the engine compartment. I too think this thing is installed to get better EPA gas mileage numbers. Nothing else makes sense to me.