K&N Drop in Air Filter for GL550
 

Hi, has anybody installed the K&N drop in air filter in their GL550? Will it throw any error codes? Part number 33-2474.

http://www.knfilters.com/search/prod...x?prod=33-2474

I replaced the engine air filter in my 2014 GL450 with the exact KN filter 33-2474 and have never received an error code. In the process of replacing the filters, be aware of a potential problem with the drivers side housing. I started a thread on this on 2/19/2015 (which you may go to if interested. It is under "Changing engine air filter on 2013-2014 GL450" to read my post and the responses received. When I ran into this issue, I eventually called the Service Manager at MB in Traverse City, Mi and the following is my post, in case you are interested.

"I just purchased the air filters for my 2014 GL450(engine 278) and find that the passenger side housing is quite easy to remove and change out the filter. The drivers side has me stymied. Connected to a rubber hose, there is a 2 inch fitting with an electrical connector(sensor?) going in to the air filter housing near the front. No matter how hard I try with my hands -- so as to not break anything -- I can not get the fitting to come out of the housing so I can remove the filter housing to replace the filter. Hopefully, someone has done this and can give some direction as to how this fitting is removed(without breaking.) so the housing can be removed from the engine compartment. Thanks."

Here is SM response and my take on the problem:

"Since I can not get fitting out of the air filter housing on the drivers side - and no suggestions have come forward - I called MB dealership to find out how they do it. The service manager looked up the procedure for MB and found no specific instructions other than remove the housing to replace the filter. He then went to a tech to find out their procedure. The tech said that they have not been able to remove this fitting that goes into the housing and have only found that they remove the electrical connection by squeezing the surround ring and wiggle the connector off the fitting. Then it is possible to rotate the filter housing -in place - without removing it from the engine compartment. At this point, the four torx screws that hold the two halves of the filter together are accessible. Separating the housing allows the housing to be cleaned and the filter replaced. DO NOT TRY TO PULL THE FITTING OUT OF THE HOUSING! Again, the service manager said they do not know how the fitting comes out and also DO NOT have a replacement part listed for this fitting!"

Maybe, things are different now, but if not, this might be of some help. Replacement is easy to do and, in my case, knowing that the drivers side housing stays in the car, will save you a lot of anguish.

Changing an air filter will not throw any error codes.

Thanks, for the detailed reply. With the filter replacement have you seen any increase in fuel economy? Performance? Thanks again.

I do not have any real statistics on either economy or performance for you. But, I do believe that I have seen improvement in both and you should also. I have KN filters in all my cars and truck and I think you will find better throttle response after installation. Depending how you drive, you should at least see better economy in highway mileage when driving at a more constant speed. I do think the advantage of KN is that they are not throw-a-ways (you don't need to do anything for at least 50K miles) and they get more efficient as they get some miles on the filters. Plus, they are washable and re-oil-able.

People still buy the K&N flat panels? My suggestion is be careful with the amount of oil you use when you clean it (assuming it's not a dry filter panel), you could cause a MAF code if excess oil gets sucked past/off of the filter.

They typically get 1hp more to the wheels, maybe 2 if it's cool out. :) Maybe 4-5whp for Turbo'd engines.

On a modern twin-turbo engine, K&N filters just don't make any sense. Even if they did provide any more air flow compared to stock filters (and that's a BIG if), what would be the point on an engine, where air intake is moderated by ECU getting feed from sensors, and assisted by two turbochargers?

Additionally, the problem with K&N filters is that they need to be oiled - otherwise they do not trap dirt/dust properly, and the oil does get into intake piping and MAF sensor, and could eventually ruin it.

That's the big advantage of using a less restrictive filter like the K&N. Your overall peak numbers may not change by much but the power curve definitely changes enough to be noticeable even by a normal user.

Having said that, I would still stay away from oiled filters of any kind. I feel money would be better spent saving for an ECU tune in the future.

I'd stay oem. less chance of dirty air into engine and maf issues from too much oil.