[s-cars] First of my own wrenching of my '01 S4

[Bob Rossato]

With regard to the BPV, there will be a myriad of opinions on this list as
to what is the best type of BPV out there, but the part number you are
referring to from the TT is 06A 145 710N.  Though some folks that have tried
them say that they also fail.

With regard to the K&N filter, I know several folks on this list use them,
either in flat panel or cone shape, but I've never been a fan of using these
types of filters on street cars.  The premise of the K&N filters is that
they allow more air in than a stock air filter and thereby should result in
more power.  That's all well and good but there are several reasons why they
are not a good idea.

First of all, K&N filters were originally designed for racing applications
and over the years, through clever marketing, have moved into the street
vehicle application.  They do indeed allow more air in (when clean) and
hence the advantage in racing where you're scratching for every last pony
you can lasso.  But the flip side of that is that they also allow more dirt
in.  This compromise is a no brainer on race engines that, depending at what
competition level you're at, get rebuilt every race or at least yearly.  And
race engines can last anywhere from 1/4 mile to at best a few thousand miles
before rebuilding is required.  For a street engine you want longevity, i.e.
200k miles plus, and a K&N filter is going to increase the wear rate on your
engine.

The other major factor that makes them a bad idea, especially with modern
engines using MAF sensors, is that the filters must be oiled.  Invariably,
some of this oil goes past the filter and the first component it hits is
your MAF.  A lot of them have failed as a result of oil coating from K&N
type filters.  And if yours were to fail, I wouldn't be surprised if your
dealer denied you coverage due to the K&N.  I think this is more of a
problem with the newer hot film, vs. the older hot wire anenometers.  The
hot wire MAFs go through a self cleaning cycle when you shut down the engine
where the wire is heated to burn off contaminants.  Don't know if the hot
film systems do this, but my understanding is they don't.  I believe the
2.7t engine in your car uses a hot film MAF, right?  That doesn't mean the
hot wire anenometers, like those in the '92-'97 S4/S6, are not susceptible
to failure from oil buildup.  It just may take longer.

Also as the filters start loading up with dirt, the K&N filters end up
actually flowing less air than conventional paper filters.  This is because
the stock filters have a lot more surface area to them.  I know someone has
done some comparison testing on them in this respect and posted the results
on the net.  I'm sure somebody will post the link.

Another "selling point" has been that they are reusable and therefore should
save you money over replacing stock paper filters.  With stock filters at
$8-$9, and replacement intervals of 20k-30k miles, I'm not sure where the
savings are.

Just my $.02

Bob

> -----Original Message-----
> From: s-car-list-bounces at audifans.com
> [mailto:s-car-list-bounces at audifans.com]On Behalf Of Single Malt
> Sent: Tuesday, March 09, 2004 6:44 PM
> To: s-car-list at audifans.com
> Subject: [s-cars] First of my own wrenching of my '01 S4
>
>
> I am an extremely novice Audi owner ... I do have *some* wrench
> experience from
> my youth ... oil changes, tune-ups, exhaust work, some brake work
> and so on.
>
> Now that my car is out of the original warranty, I felt like
> tinkering a bit.
> I've been told that replacing the air filter with a K&N variety
> would yield
> some more power and could hardly effect the Audi Assured coverage I am now
> enjoying.  I've also been told to replace the diverter valves
> with ones from
> the Audi TT ... anyone have any info/insight (including part
> numbers) on this?
> Any other EASY modifications that should be done right away?
>
> You can view pictures of my little project at:
> http://www.inners.com/s4airfilter/airfilter.html
>
> I came across an extra part under the filter.  Looks like some kind of
> retaining clip.  I could not find a place that was obviously
> missing anything.
> Anyone able to identify this? -third picture from the top
>
> I also found out that the most unreachable retaining clip had not
> been attached
> at some point.  Yet another reason to start undertaking the task
> of DIY repair!
>  I found it easiest to do this clip FIRST. It took a second
> person to press
> down on the edge of the upper cover using a long rod, while I
> fiddled that clip
> into place with a long screwdriver ... is there an easier way?
>
> I found that it is quite easy to drop parts down into the belly
> pan.  I was
> lucky with the O-ring that seals the MAF connection and was able
> to fish it out
> with a modified hanger.  One of the hose retaining clips,
> however, required
> lifting the front end and dropping the belly pan to retrieve it.
> A lift would
> *sure* come in handy!
>
> I would really like to hook up with a local lister (Denver, CO)
> who might be
> interested in mentoring ... anyone??
>
> Steve, looking for a mentor, Inners
>
> aka...
>
>
> =====
> ##########################################################
> Single Malt
> '01.5 S4
> Garaged at 9200ft
> just outside Denver, CO
>
>
>
>
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