Hey all,
Heres an update. Took a pic of the mystery filter that is inside top of the filter box. Gray, ribbed filter. It did not fall out or wasnt loose at all. Is it a permanent filter, carbon, charcoal? What if I remove it, will I gain some extra power....haha j/k. There was a number on it: "PP TX20". I googled it but nothing came up. Driving me nuts. I was lookin on sites that describe how to replace the air filter and that filter was not on the pics?! Ideas??

Can I see a picture of your oil filler cap? That looks like the airbox from a 325i SULEV. I don't think there was a coupe with the M56 engine in it.

heres the pic of the oil filler cap. I had no idea what SULEV is...had to google it. lol. If it is, ultra low emission vehicle, that sucks. Im sure the car is restricted to the max and im loosing power. Any way, what else can you tell me about this? Is this unique? I have no idea....


also re-read your post to my OP. Yes my oil filler cap is hinged...just changed the oil so I remember that... :)

Ok- so what IF that additional air filter is removed?

I can't imagine why there would be two air filters in the box. Seems like one would be enough. And if they wanted to have more filtration, they would just make the one element deeper.

Anyway, I don't see how it would hurt to remove the gray pleated filter. BTW, that looks like the cabin filter on my 2001 e39 530i.

SULEV = Super Ultra Low Emissions Vehicle. Can you believe they used 2 superlatives. Guess they had to do something after they came out with a lower emissions vehicle than the Ultra Low Emissions Vehicle!! :eyecrazy

Anyhow, I think that filter is to keep hydrocarbons from eminating OUT of the intake manifold and back into the atmosphere. I'd take it out, it's certainly restricting your intake.

SUBJECT
2.5 Liter Six Cylinder Engine (M56 SULEV)


MODEL
2003 325iA (E46) sedan, coupe and sport wagon with automatic transmission


SITUATION
With the introduction of the 2003 E46 325iA (sedan, coupe and sport wagon), the M54 2.5 liter engine has been further developed to meet stricter emission requirements.


The updated 2.5 liter engine designated M56B25, has been phased into production on E46 Super Ultra Low Emission Vehicles (SULEV) along with various other emission control system changes listed below.

The M56B25 power output and vehicle performance is the same as the comparable model equipped with the M54B25 engine.

SULEV models listed above will be sold in California, New York and Massachusetts as 2003 models and in Vermont starting in 2004 model year.

The M54B25 engine will continue to be incorporated in these models (for all other states) for the 2003 model year.

In addition, these vehicles are certified as Partial Zero Emission Vehicles (PZEV):

The vehicles meet the SULEV tailpipe emission standard, which is approximately 1/5 of the ULEV standard.

The vehicles conform to the Zero Evaporative Emissions requirements.

The emission relevant components are warranted for 15 years or 150,000 miles.

System components used to achieve "Zero Evaporative Emissions" requirements:


HC block in the air intake system:
Hydrocarbon escape via the intake system is prevented due to the use of an additional carbon filter (1) incorporated in the air filter housing and a "closed" throttle valve actuator (2).


Fuel system components:
All metal fuel system components (fuel rail (1), injectors (2), tank ventilation valve (3), etc.) are made of stainless steel and are fastened together using coupling type connectors (4).


Fuel tank and tank ventilation system:
The fuel tank (1), tank filler neck (2) and evaporative canister (3) are made of stainless steel.


Crankcase ventilation system:
The crankcase ventilation valve (1) is incorporated in the aluminum cylinder head cover (2).

System components used to achieve SULEV tailpipe emission requirements:


(1) Dual down stream catalytic converters
(2) "Warm up" catalytic converters – high cell density technology
(3) Upstream oxygen sensors – wide band technology
(4) Pistons – only 3mm fire land
(5) VANOS – set to fixed position during start up for improved engine start
(6) New style fuel injectors – 4 hole design (5 bar fuel pressure)


Secondary air system with secondary air mass flow sensor (1) used for improved monitoring of secondary air flow.

In addition SULEV models also incorporate a "Direct Ozone Reduction System". The external heat exchange surfaces of the radiator are coated with a catalyst which reduces the ozone in the ambient air drawn through the radiator.See that bold part? Don't remove the filter.

Mad dragon,

Yes thank you. I see the bold. Now its not that I dont care bout the environment, but if that carbon filter is removed I was more concerned about the car finding out and possibly giving me the SES light. If theres no system checking on that filter, who cares if its there? I dont live in Cali, Im in FL and we havent had emissions testing in years. I could take the CATS off and no one would know...not that I would.

thanks again

I'd leave it. You're really not going to gain any power if you remove it.

After reading MAd Dragon's post, I'd just leave it in there, too.

I'm really surprised that they did that. It's sort of hard to imagine that it would make that must difference, but I guess it does.