Non-OEM Air Filter - Caution!

Post by **harrier** » Mon May 15, 2017 11:39 pm

I was considering switching to a non-OEM air filter for my C7 RS6 (eg. ITG Air Filter for Audi RS6 4.0 Litre V8 Turbo (06/13>) | ITG-BH304), in order to maximise power output. Has anyone got any before and after figures though, changing air filters alone, to show any of these actually can improve BHP; in other words, do OEM air filters restrict performance?

More importantly, I am very reliably informed that the after-market air filters often are finely oiled (they even warn that excess oil may well be apparent when the filters are handled/fitted). The oil is there to trap fine particles, but this oil will be sucked into the engine and the MAF sensor(s). The sensor compares air on two sides of a "diaphragm", I am told, and as the intake side gets coated with a very thin film of oil it eventually reads inaccurately and the engine runs increasingly damagingly lean. Only a very small part of the sensor can ever be reached to be cleaned and the oil on the remaining contaminated part would only migrate out over the cleaned part then anyway. The only solution therefore would be fitting a new expensive MAF sensor.

Has anyone any experience of this and if this is indeed the case then are there any air filters that definitely won't do this and are worth fitting/worth the money? What do you guys think and what're your experiences? Are any air filters worth fitting or are they just a nice idea or worse than that potentially harmful (for the above reasons, that make perfect sense to me)?

Post by **RS6chris!** » Tue May 16, 2017 6:10 am

I fitted an after market Pipercross filter to my pre
Fl 6.

No issues at all...more induction noise etc

Post by **chunky79** » Tue May 16, 2017 6:26 am

OP, are you going to get the car re-mapped? If not, then i'd just stick with oem.

Post by **MikeFish** » Tue May 16, 2017 8:18 am

There is an element of truth in that. I suspect my rs4 suffered from oil on the MAF from an oiled aftermarket filter and this is the reason the Revolution / pipercross carbon air intake was switched to an oil free filter. The maf is only about £120 so not what I'd call an expensive repair bill in RS terms and I'm pretty sure the engine won't suffer from any permanent damage from a failed MAF. So the simple answer is don't use any oiled filters but if you do I don't think it will be catastrophic. But regardless, I didn't think the 4.0tfsi used a maf?

Post by **jipettersen** » Tue May 16, 2017 8:23 am

Had my K&N fitted when remapped. No HP gains with only filter , but my tuner said the car loose performance when the OEM gets dirty. K&N and certainly other dont.
Little more intake noise.

Post by **MartayMcFly** » Tue May 16, 2017 9:35 am

I heard/read a lot about the K&N cone filters in RS4 Revolution carbon intakes messing with MAFs, but they don't mis-read the flow they just die and throw up an ECU light. There was something like a gen 3 cone that wasn't oiled that was recommended and as far as I can remember once I'd changed the filter and sensor both worked fine (and probably still do to this day).

As for performance, I'd be surprised if the OEM item was harmfully restrictive. You might get a bit better noise with an open/cone intake, but you're not going to see useful gains just from a different branded filter in the stock housing.

Post by **almoRS** » Tue May 16, 2017 10:00 am

I fitted a BMC filter as soon as I got the car as used them previously on all other cars. Its be running with it for 2 years now and no issues. I don't think it adds any performance where it has changed noise in the past.

Post by **tartan_rob** » Tue May 16, 2017 12:27 pm

Even if it leaves trace oil on the thermocouple of the MAF, wash it down with solvent. Job done.

Post by **Golfather** » Tue May 16, 2017 3:49 pm

No mafs in c6 or c7

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Post by **harrier** » Tue May 16, 2017 11:04 pm

All seem pretty agreed that the OEM air filter isn't at all restrictive, so no no power gains when switched.

There do seem to be divergent opinions as to whether the C7 RS6 has a MAF sensor, so I'll have to do my own checking, but can anyone say definitively?

Post by **MikeFish** » Tue May 16, 2017 11:09 pm

Who says it has one? Golf and I have both said it doesn't and the others haven't mentioned it.

Post by **MikeFish** » Tue May 16, 2017 11:17 pm

Besides, why are you even concerned about the MAF, there are plenty of dry filters to use so it's not even an issue if there was a maf.

Post by **shanek** » Wed May 17, 2017 1:55 am

With regards to power/performance increase after performance air filter installation, there will be no instant increase in power after installation due to the greater airflow allowed with the less restrictive filter as the ECU has to learn over time that it can increase the fuel flow to match the greater airflow. Porsche ECU's have been like this for a while allowing the ECU to adapt to the engine as it breaks and beds in allowing things like less restrictive exhausts and air filter to, over time, increase performance without any need for a remap.
As for a MAF sensor, I haven't seen anything in the air intake system that looks like a MAF sensor, i believe any airflow/boost measurement is done downstream of the Turbo and charge cooler in the intake manifolds.

Post by **Y3CHR** » Wed May 17, 2017 6:35 pm

I fitted the Forge hi-flow unit and love it, this has come with proven gains during development. I will see once I get the mapping done I guess.

Sounds great and looks amazing in he engine bay

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Post by **chunky79** » Wed May 17, 2017 6:54 pm

That's does look tidy, although a shame they didn't match the direction of weaves on the 2 parts. Are they cone filters inside? Bet that cost a pretty penny!!!

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