MRC Air Filter Failure

[cammmy]

Hi All

Firstly, this isn't a dig at MRC and I'll give the back story. I just wanted to say that if you have their filters, check them regularly.

As per the "interesting development" thread the previous owner of the car didn't do any of the maintenance himself and was unaware that the owner before him took the car to MRC for a stage 2 setup/tune, including air filters. This was 7 years ago. I had seen in the service notes "aftermarket air filters fitted, not replaced" or something along those lines and realised it may be possible that they hadn't even been cleaned in 7 years. I just opened up the air box and found the attached.

Now, I have no idea if these are supposed to be a washable/reusable filter or disposable but either way, if you have them just keep an eye on them, as I have no idea how long these have been going through the intake/engine. Obviously a filter shouldn't be left alone for 7 years but at the same time, this isn't a good failure mode for them. I can only assume these are meant to be disposable.

[welwynnick]

Hells Bells.

You won´t catch me using anything but an OEM filter

Nick

[cammmy]

I'm just hoping it's only happened between the last service and now. I can't imagine a garage would see that and not tell the owner.

[grahamh84]

Should be using these ones if car has been remapped - “Audi RS6 5.0 V10 Quattro Bi-Turbo BMC Performance Air Filter Replacement Service Kit”

[cammmy]

I've just ordered those. I couldn't find OE ones online and I can't get to the dealer as all my other cars are now SORN

[grahamh84]

Mines on stage 2 with these BMC ones even sometimes on Eurocarparts discounted - change them once a year

[welwynnick]

Are the MRC filters foam rather than gauze?

[cammmy]

Yup, based on appearance and description, I believe they are a rebranded version of these:

https://www.eurocarparts.com/search/909 ... KBEALw_wcB

These do state they are washable and "can be used over and over again". So I'm surprised to see both disintegrate in the same way.

[Golfather]

MRC ditched these years ago for BMC, for this very reason. They recommended everyone to swap them out as soon as this was brought to their attention.
Do a search on here

[cammmy]

Okay cool, glad to hear they aren't still selling them.

[c3nturi0n]

Again bit of FYI (based on personal experience and by no means i want to slate or dig at anyone!

I did replace my old MRC's with BMC filters (ordered vias ECP)... car was okay for first 20-30miles and then it started producing some very odd 'misfire' like symptom. So i started hunting for issues and did my usual 'it's the other stuff and not filters'. I replaced MAF sensors, cleansed throttle bodies, checked for hose leaks, replaced spark plugs/ etc. and it was pretty much the same. I recently replaced BMC's with a new set of OEM air filters and the car is now running like a dream.

Hope that helps.

[cammmy]

I have heard that the oil from the cotton filters can get onto the MAFs and mess with them. I guess I'll see. Given the amount of oil that's in my intake due to either the PCV or turbo seals, I hope this won't make a difference.

[welwynnick]

I don't think it uses an MAF - just pressure and temperature sensors. Interesting observation though. I can't imagine the ECU was detecting too little pressure drop across the filter....

[cammmy]

That would make sense, I was wondering how a MAF would work when placed downstream of the turbo.

[IanH755]

That would make sense, I was wondering how a MAF would work when placed downstream of the turbo.

Yeap there's no MAF/AFM on these, just 3 MAP sensors instead - 1 per turbo just before the throttle body and 1 in the intake manifold.