K&N Filters....Any good?

[TDi_B5]

Does anyone have a K&N air filter in their passat, whether petrol or diesel? I am tempted to buy one, not by the price (£40ish) but the gains in horsepower, improved acceleration & air flow etc etc and the fact that they don't need cleaning for 50k or so.

Thoughts...?

[Ross 1.8T]

In my opinion they are too heavily oiled for use so close to the MAF sensor. Go for a green cotton or BMC panel filter. They'll flow at least as much air but won't wreck your MAF in the process.

[passat 130 tdi]

isnt most of the air stored in the intercooler anyways , so nice and cool before it enters the turbo ??

with reguards to the maf sensor , is it located in the air box and what do u guys clean it with ? many thanks.

[mac v6 sport]

i have a v6 tdi,i put on a k&n and dont think it helped at all,you can clean them with petrol and refluid them with the oil you can buy for the job,a decat will give you a bit more noticeable power rather than the filter

[Ross 1.8T]

isnt most of the air stored in the intercooler anyways , so nice and cool before it enters the turbo ??

with reguards to the maf sensor , is it located in the air box and what do u guys clean it with ? many thanks.

Wrong way round mate. The route the intake air takes is from the airbox through the filter to the turbo where its pressurised and forced through the intercooler to the intake manifold and into the engine. Its by no means cold after passing through the intercooler, its just slightly cooler than it was after passing through a turbo spinning at 100,000 rpm.

The MAF sensor on the B5 passat 1.8T (mine anyway) is in the lid of the airbox. You need to remove it to clean it. Use either Isopropyl alcohol or electrical contact cleaner, both are available from Maplins or *********.

Don't use anything other than the fluid to clean the maf. Put the whole unit in a ziplock or freezer bag and pour in the alcohol. Slosh it through the Maf sensor for a few minutes then remove it from the bag and allow it to dry naturally for an hour before refitting it.

I've tried Green Cotton, BMC, Dynatist, Carbonio and RAMAir on various incarnations of the VAG 1.8T engine and I'm convinced that nothing gives better performance than a clean paper air filter (the standard one).

[TDi_B5]

Nice replies chaps, this question will probably change the direction of this thread, but oh well, thats what we're here for! Ross 1.8T, you mention the MAF sensor, I've never touched mine, I'm not entirely sure where it is but, does it need to be cleaned? If it is cleaned, will it improve the car's performance? I have a '97 TDI 110 and she's approaching 180k and running sweet as the day I bought her, I do all the servicing myself and I'm always looking for ways to improve or atleast prolong the life of my engine. There are douzens of posts on MAF sensors, but I'm still a little ignornant to what its all about....!

[Ross 1.8T]

Nice replies chaps, this question will probably change the direction of this thread, but oh well, thats what we're here for! Ross 1.8T, you mention the MAF sensor, I've never touched mine, I'm not entirely sure where it is but, does it need to be cleaned? If it is cleaned, will it improve the car's performance? I have a '97 TDI 110 and she's approaching 180k and running sweet as the day I bought her, I do all the servicing myself and I'm always looking for ways to improve or atleast prolong the life of my engine. There are douzens of posts on MAF sensors, but I'm still a little ignornant to what its all about....!

Performance will degrade gradually over time as the MAF gets out of spec with age and residue on the heated wire. Having just had a look at ETKA, the MAF sensor on your car is removed by taking the hose off of the top of the airbox and then removing the screws that this exposes. The MAF sensor tunnel complete can then be removed from the inside of the airbox cover and cleaned using the method I gave earlier in the thread.

The ECU uses input from the MAF sensor to work out how much air it has to play with. The MAF itself is nothing more than a resistor, a small length of heated wire not unlike a domestic electric heater setup that is cooled by the incoming air from the air filter. The cooling of the wire affects the voltage sent back from the MAF to the ECU. The ECU then calculates how much intake air there is based on the voltage it receives from the MAF. This allows the ECU to adjust fueling to suit the amount of available air. Not so important on a diesel engine which will take a full charge of air on each induction stroke regardless of how much fuel is introduced but very important on the petrol (especially turbo) engines where the mixture must be finely regulated.

This is very relevant to the issues raised when adding an aftermarket air filter to the equation. You're unlikely to find another car where the MAF sits closer to the filter than on the Passat B5. We know that over time, residue builds up on the sensor wire and degrades its efficiency. Sticking a heavily and stickily oiled filter right next to it is a recipe for a MAF replacement bill in my opinion.

The simple rule of thumb is that if the car drives better with the MAF sensor disconnected, it needs cleaned.

I think you'll be pleasantly surprised if you give it a clean. For what its worth, I think you've got the pick of the diesels. 130s are nice but they don't last as long as the venerable old 110 and at over 100k miles they're a bit like OAPs, a new ailment every month.

[TDi_B5]

Great stuff, I realise what the MAF is now, didn't realise it was so accessible and that I've been looking at it every time I change the air filter. What part of it actually needs to be cleaned? Is it the gauze type bit where the air is drawn through? And is it okay to unplug them and remove them or will this throw up a load of issues?

[Ross 1.8T]

Its the black plastic insert that protrudes into the small cylinder. The MAF sensor wire is inside this insert. Its fine to unplug and remove it, it'll log a fault code if you drive with it unplugged but it makes no difference to the running of the car once it re-connected.

[Crasher]

K&N filters are excellent and WILL NOT damage your AMM. I have sold thousands over the years and have not had a problem, in fact I am sure that AMM’s fail less often with a K&N although why that is I have no idea. However as for power gains, they are negligible. On a Golf VR6 we saw 170PS on a standard paper filter and 174PS on a K&N direct replacement panel filter. At the same session also tested an induction kit from another company (who shall remain nameless) on the same car and saw 156PS!