Scirocco Central

Hi all,

Recently had a go at fitting a k&n filter that was also fitted my old golf (using same filter).

For some reason when engine is warming up the car hunts quite bad when in low gears going at crawling speed. Once engine is warm it goes away. I've taken the filter out as it does my head in and it runs fine on the stock filter.

The k&n by the way had been cleaned before installation.

Anyone else experienced this issue?

You might want to read this...... http://www.sciroccocentral.co.uk/forum/ ... ter#p34061" onclick="window.open(this.href);return false;
Even if you clean and "dry" the K&N, it still releases minute droplets of oil which then deposit on the MAF sensor.

There are two types of MAF, Hot Wire and Thin Film. Hot Wire types just burn the oil droplets off so not affected. Thin Film, the oil attaches and then distorts the airflow reading, hence the fuelling and so leading to what you experience. Initially the engine works fine but as the oil deposits build up, so the correct fuelling deteriorates.

If you are going to use an aftermarket filter, use a dry type.

Had a K&N panel on my Corrado years ago giving lumpy idle and slightly rough running. Consigned the K&N filter for that MAF system to the loft and has run on OEM filters fine ever since.

(Doesn't affect the 1.4TSi's as they use pressure sensors and no MAF, just 2.0ltr TSi & TDi)

C.

I knew he answer but no where near that concisely, nice one RW1

Looks like my problem is now happening with th stock filter.

whats the best approsch to ensure the dealer repairs/swaps my MAF as i presume my suggestion of the same wont wash unless they do tests?

mikealpha60 wrote:Looks like my problem is now happening with the stock filter.

Don't forget, the MAF is now covered in K&N filter oil, so even an ordinary filter will not rectify the situation unless the MAF is cleaned. I normally clean the MAF with IsoPropyl Alcohol by spraying. What mustn't be done is to use a "tool" ie. brush , directly on the sensor inside the tube . That will result in damage. It just needs to be washed with alcohol. Other agents like carb cleaner can damage the sensitive sensor and electronic components due to the way they attack the surface to clean a carburettor. IsoPropyl Alcohol is neutral. Or use try using electrical contact cleaner from somewhere like Maplins as I wrote in the Malcolm topic.

Its available on line quite cheaply at £2.99 / 0.5ltr if googled. At the chemist its £12 / 0.5 ltr (if they have a licence to sell alcohol products). 250ml quantity is also available. You will need to find something to spray it with or simply keep pouring alcohol over the sensor head to wash it.

The K&N oil doesn't damage the sensor, wrong cleaning technique does. After cleaning the MAF sensor the engine should start to operate normally but a little time will be needed for the ECU to re-adjust itself based on the Lambda readings v stored settings.

The dealer will have a hard time seeing a fault unless a lambda fault shows up for rich mixture. My guess there won't be any fault code and as in that link to Malcolm's experience, they will find the filter oil as it usually stains red with K&N. They won't have the time to start analysing the engine fuelling etc.

The alternative is this fault is nothing to do with the filter and just coincidence. On refitting the paper OEM filter I would have expected the problem to immediately continue if the MAF was contaminated. Your posts imply that is not the case and there was a period on refitting the OEM filter where the probem didn't occur for a while ???

C.

RW1 wrote:You might want to read this...... http://www.sciroccocentral.co.uk/forum/ ... ter#p34061" onclick="window.open(this.href);return false;
Even if you clean and "dry" the K&N, it still releases minute droplets of oil which then deposit on the MAF sensor.

The people at K&N disagree strongly with this claim:

http://www.knfilters.com/faq.htm#27" onclick="window.open(this.href);return false;
http://www.knfilters.com/MAF/MAFTestresults.htm" onclick="window.open(this.href);return false;

Of course, they can't really be expected to be 100% objective on the matter. However, the research they've done still seems quite decent and condifence-inspiring.

RoccoScientist wrote:Of course, they can't really be expected to be 100% objective on the matter. However, the research they've done still seems quite decent and condifence-inspiring.

Love it. If they said it did, they wouldn't sell any airfilters! Or maybe they just didn't test any VW Thin Film MAFs.......

Cleaning the MAF is the first call to eliminate it as the cause.

C.

RW1 wrote:Love it. If they said it did, they wouldn't sell any airfilters!

True. Then again, the car manufacturer also has a strong interest in blaming aftermarket parts when the car starts to act up. I'm not saying one should believe K&N's research without scepticism, but at least to me it still holds some value that they've taken the time to at least pretend (assuming they're dishonest) they've backed their claims with research, since it's the best I've come across. You'd need an objective, independent study of the matter to get to the truth, but where can you find one?

Of course, cleaning the MAF is advisable and helps find the cause, I'm not denying that in any way.

Not my practical experience with K&N as I originally posted.
Done more than one Thin Film MAF/K&N cleaning out with the same result.
Thats an independent study
Love to know which MAFs they tested......

C.

See i used to have a Golf TDI and folks on those forums said that cleaning your MAF using similiar method wasn't successful. Are we saying it is doable then?

The first one I ever did was in 1997 with a Thin Film. The K&N panel filter was on for 2 weeks. Cleaned the MAF, never had a problem since, still running today on OEM filters after the cleaning. Two other's done later, still running normally to date.

To do.....

You will need to extract the MAF from the side of the airfilter box. The difficult end is the large circular duct clip on the engine/turbo side of the MAF and getting that released. I use this....
Basically the slide carrier in the bottom right of the photo engages with the two lugs on the circular duct clip. The tool squeezes and locks to create a larger diameter of the circular clip and so it can be slide out of position to release the engine/turbo intake duct off the MAF.

A plumber's adjustable jaw wrench tends not to have the jaw width to engage the two clip lugs unless its a very big variation of the tool.

The other end of the MAF is attached to the side of the Air Filter box by two Torx bolts (1.5Nm torque setting). And just release the electrical connection.

In the past I've used two jam jars. Put 200ml of IsoPropyl Alcohol in one. Put the MAF on top of the other jam jar and poured through the alcohol which is caught in the lower jam jar. Then put the empty pouring jam jar under the MAF and poured the contents through again. Washed it about 5 - 6 times with the MAF reversed round on the 4th, 5th & 6th washes. On a 7th pouring, wash the MAF body internal wall by slightly tilting and rotating at the same time. Store that dirty alcohol away for disposal or further use, separate to the clean alcohol still in the original container. Clean one of the jam jars and pour in 50ml of clean alcohol. Wash that over the MAF sensor once. Leave the MAF to dry/alcohol evaporate for 30 to 60 mins. Then refit the MAF to the intake duct/airfilter and connect up electrically.
(NB. It alcohol, so no smoking or ignition sources nearby and do in a well ventilated area.)

Alternatively, put the MAF in a large plastic bag that seals. Pour in the Isopropyl Alcohol and wash it around for a while in the bag.

Before refitting, you may want to wipe the airfilter box internally above the air filter panel area and the apperture to the MAF attachment point to remove K&N oil residues. The ducting downstream of the MAF doesn't matter as it will not effect the MAF and part of the length will be contaminated by the engine breather.

C.

Hi Guys

I've been having exactly the same symptoms with my TDI 170 as mikealpha60 and following RW1's advice have removed the K&N filter, however, I am still getting the same problem. Does anyone know where I could get the MAF filter cleaned other than the dealer as I don't fancy doing the job myself. The car also has a TDI-Tuning box fitted, so I hope it's not that causing an issue, any advice would be much appreciated.

Regards
Martyn