Open Air Filter: Pros & Cons Explained

Hey everyone,
Okay, so I naturally started by using the search function, but I couldn't find any answers!
I was wondering how I can install an open air filter in my B4 TDI ('93), specifically regarding the mass airflow sensor (MAF)! How should it be mounted? Would you even recommend doing this?
Thank you in advance!

Best regards, Mike.

P.S.: 1Z machine

What do you mean by 'open,' referring to a sports air filter? If so, there used to be something about that here, comparing a sports air filter to a paper filter. The result was: no other mass airflow sensor (MAF) values.

Bosch specifies the following requirement for the air filter used with the mass airflow sensor (MAF):

Separation efficiency > 99%
Maximum particle size on the verschandeln air side: 20 µm.

and this applies over the entire lifespan of the filter (also known as the replacement cycle).

You don't do that with an 'open' one.

In addition, the mass airflow sensor (MAF) must not come into contact with any oil mist, as this makes it difficult to use an oiled air filter. Too much oil will damage the MAF sensor; too little oil will damage the engine.

With a turbocharged engine, it doesn't really make a difference unless other modifications require changes to the air intake system.

CU Gremlin.

Okay, I understand. Please provide the German text you want me to translate into English. I will only provide the translation.

/viewtopic.php?t=2917

Hello Rainer,

Okay, that's all well and good, but it doesn't help me at all... I'm talking about an open sports air filter (mushroom type). If you install something like that, I want to know how and where the mass airflow sensor (MAF) should be mounted – right after the filter?!

Best regards, Mike.

That is NOT MINE!!!

Just so that no one complains .

Gremlin has essentially said everything there is to say!
Install the LMM (lambda measurement module) behind the air filter and then prepare yourself for the fact that its lifespan will be limited. Therefore, it doesn't really matter whether it starts 2 cm behind the filter or 20 cm behind.

Hello Tribune.inc,

In addition to the mass airflow sensor (MAF sensor), which is failing faster than usual (VW stipulates that vehicles with MAF sensors should not have paper air filters), and considering what 'Gremlins' mentioned, you should be aware that in this process, air is drawn from the engine compartment. This makes me wonder what the purpose of the intercooler is then.

If someone installs something like that, I'd like to know how and where the mass airflow sensor (MAF) should be mounted... right after the filter?!




b) Oil
Sobald Öl in größeren Mengen auf den Sensor gelangt, wird die thermische Bilanz am Sensor gestört. Je nach Ölmenge können größere Kennlinienabweichungen durch eingebranntes Öl auftreten. Außerdem wirkt das Öl als Haftvermittler für trockenen Staub. UnzureichenDistances from:
* Crankcase ventilation.
* Turbocharger (for engines with turbocharging).
* Exhaust gas recirculation (EGR)
Regarding the HFM5, potential causes for the sensor being wetted with oil are possible.

Is everything alright? / Is everything clear?

Sure, here is the translation of the text from German to English:

'Cu Gremlin'

Thank you to those who appreciate my contributions and don't buy any open ones!!

Best regards, Mike.

Good decision.

Hey everyone, I've been learning some new things again...

Okay... my car doesn't have a lambda sensor (manufactured in May 1993). I also have an air flow meter, so the old type! I knew that already, but not that it's related to having an open air filter!

This is my engine.
http://mitglied.lycos.de/ferkelbabe/Audi_80/DSCF1866_1.jpg

I was just thinking about, purely as a trial, installing an open air filter...
I would like to know if there is an adapter available for my language model (LLM), or do I need to create something myself?
Whether the LMM will now become obsolete faster or not is debatable; I just want to try it out experimentally.
Thank you in advance!

Best regards, Mike.

If I see your engine bay like this, I would immediately make an intake adapter for a naturally aspirated engine so that the air filter gets at least some fresh air; otherwise, you'll only be drawing in warm air from the turbocharger. And the warmer the air being drawn in, the less fuel will be injected...

Looking at your engine bay, I would strongly recommend getting an intake adapter for an open filter as soon as possible, so that the air filter can get some fresh air. Otherwise, you'll only be drawing warm air from the turbocharger. And the warmer the air being drawn in, the less fuel will be injected....

I'll do that too, somehow I'll manage to fit it in... I'm already excited to hear how this thing sounds!

Best regards, Mike.

hi tribune,

I can't quite believe you shouldn't have an LLK (low-temperature coolant cooler)... I see what look like pressure pipes in your engine bay, and besides, you have a TDI and not a TD.
You probably have an LLK!

The air intake modification works great on the 80. The airflow is directed behind the hood, towards the air filter box.

Hi Micha,

Furthermore, you have a TDI and not a TD.


The T4 also had a TDI engine without an intercooler!