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Schaumburg Throttle Body: Experiences

Unofficial Notes on the Schaumburg Modified Throttle Body

    I. WHAT IS IT?
       D. AIR FILTER

I have two purposes in mind as I type this.  First and 
foremost, the intent is to document the procedure of 
installing the throttle body, so that others who might want 
to do it themselves may have an easier time doing it (and 
deciding whether or not to do it).   Note: This is NOT
an undertaking for someone who has never done anything

The second purpose is the one that I'll address first, though,
and that is to share my impressions of the modification.

CAVEAT: This is NOT official information!  It's just me,
sharing my experiences, observations, and wild guesses.
As in many other aspects of my life, I assume NO 
responsibility here.  :-)  

NOTE:  My car is a '96 A4 Quattro, manual transmission.


It's a throttle body for the Audi 2.8L V6 that has been 
modified by Schaumburg Audi.  Craig Jones is the expert
there, and he can be reached at 1-847-843-9975.  The stock
throttle body has a primary butterfly valve that looks to be, 
oh, about 1.25" or so in diameter.  The body leading up to it, 
though, appears to be less than an inch in diameter.  
Schaumburg basically just bores out this restriction so that
no place in the throttle body is the airflow constricted to 
less than the diameter of the butterfly valve.

Price: (at least what *I* paid) $295 for the modification,
or $325 for the modification plus a K&N panel filter.  Price
includes one-day UPS shipping (but not the shipping to
send your throttle body there).


Schaumburg claims *no* increase in overall HP.  The claim is
that the engine breathes better down low.  Some people
have claimed slightly better gas mileage is seen after the

I've only driven the car twice since I did the installation
last night, which really isn't enough to get a good driving
impression.  I also replaced the stock paper air filter with
the K&N panel filter (not the FilterCharger).  My initial
impression is that there's not a dramatic difference.  The
car feels stronger in the 2500 to 3500 rpm range, though.
I generally have thought that the car doesn't seem to really
pull until around 3500rpm; my impression is that it now
begins to pull well at around 2700.  I'm guessing that if one
drew a torque curve, the modified engine's graph would 
probably be a bit higher from 1500 to 4000, at which point
they'd merge.  NB that this is just a wild assumption.

Driveability is otherwise unaffected.  The car sounds exactly
the same.  Don't know about gas mileage yet.  Improvement
is noticeable, but not strongly pronounced, and affects
mostly the 2000-3500 rpm range.  YMMV.


Axiom: Engines get hot when you drive the car.
Corollary: You will burn your hands when you work on an
  engine within a couple hours of driving the car.


Once you've got the modified throttle body, take a look at it.  
There's an electrical connector at one end... this is the 
position sensor.  At the other end is the black plastic cam
that the throttle cable attaches to.  The TB mounts at the
rear of the engine, with the position sensor at the bottom
and the throttle cable cam at the top.  It mounts to the
engine with four bolts, you can see the holes.  A black plastic
air plenum feeds air into the throttle body from the rear.
It doesn't fasten to the TB, but the two pins you see on the
TB are alignment pins for the plenum to slide onto.


The mounting bolts are hex sockets, so you'll need a hex
("Allen") wrench of the proper size.  I believe it's 6mm.  I 
*strongly* recommend that you get a ratchet driver that has
a 6mm allen bit... it is doubtful that you'll get the TB off 
if all you have is the standard Allen wrench (hex bar of metal
bent 90-degrees into an L-shape).  They're a bit tough to get
to, and they are put on *tight*.  If there's such a thing, a
socket set with a 6mm allen bit, along with a short extension,
will be ideal.

You'll also need:
- 10mm wrench or socket
- various screwdrivers
- first aid cream, band-aids, burn cream   :-)


NOTE: in the following, "right" and "left" are from the 
perspective of you standing in front of the engine... i.e. the
driver's side (for US cars) is on your right, the air filter
box is at the left in front, etc.

1. Remove the engine cowling by pressing down and turning the
   4 screw catches 90 degrees with a screwdriver.

2. Remove the air hose which runs from the air box to the 
   intake plenum, by loosening the hose clamps on each end.

At the rear of the engine compartment in the center, you see 
some vacuum hoses around two solenoids on a black plastic thing.
This "think" is the air plenum.  The throttle body is beneath
it, and the plenum extends down behind the TB.  To remove the
plenum, you need to remove some hoses.  There are probably
a half-dozen combinations of hoses that you could remove to
do this... here's what I did.

3. Remove the electrical connectors from each of the 2 
   solenoids (push in the metal spring clip to release them,
   and they pull off easily).
4. There are two vacuum hoses that come from the front right 
   of the plenum and attach to the solenoids; on my car, 
   one is blue and one is brown.  Disconnect each of these 
   two hoses from its solenoid.  (They just pull off).

5. To the left of the left solenoid is a Y-connector.  Off
   the left of this Y-connector comes a black hose, that then
   goes off to the left-front of the plenum and disappears.
   Disconnect this hose from the Y-connector.

6. At the right rear of the plenum, a vacuum hose comes onto
   the plenum.  Disconnect this hose from its connector.

That should free the top of the plenum of all external
vacuum connections.

7. Remove the two 10mm bolts at the front of the plenum.  

8. Look underneath the area of the plenum where the air hose
   was attached.  You'll see another black hose, maybe 3/4",
   that leads to the left side of the engine.  Remove this
   hose from the plenum (it pulls off, it may help to grab
   the ring that you'll see and twist a bit)

9. On the other side is the same type hose, leading to the
   right side of the engine (I assume these are EGR hoses).
   remove this hose from the plenum.

10. Right below the hose you just removed, you'll see a
    small vacuum hose that attaches to the throttle body,
    on the right side.  Pull this hose off the throttle
    body (and if you think it's tough to get to, wait 
    until you have to reattach it!)  :-)

11. The plenum is now "free" to be removed.  The only thing
    holding it in place are the two alignment pins on the
    throttle body and the air intake on the throttle body,
    all of which just slide into the plenum.  Slide the 
    plenum backwards until it is clear of the alignment pins
    and air intake, and lift it out.  This is easier than
    it sounds, because at first you'll think that the engine
    firewall is about 1/8" of an inch too far forward.  Keep
    at it, you'll get it!

Axiom: Metal conducts heat.
Corollary: If the engine is very hot, so is the throttle body.

11a. On the left side of the throttle body is a fairly large
     (about 1/2") vacuum hose, that is held on with a clamp.
    Loosen the clamp and remove this hose.

12. Detach the square-bar linkage from the throttle body as
    follows.  First, look at your modified throttle body to
    get an idea of which part is supposed to come off.  The
    square bar slides through a black piece of plastic; this
    plastic part has a socket which is snapped onto the ball
    that is a part of the throttle body mechanism.  So you
    want to snap this plastic piece upwards and off of the
    ball on the throttle body.  I used two small flat-blade
    screwdrivers, one on each side of the ball, and pried
    upwards.  (I believe this is the cruise control linkage,
    may also serve to keep idle speed up when the AC 
    compressor is on... I don't know).

13. Remove the throttle cable.  Do this by first turning
    the throttle cable cam clockwise (increase throttle).
    You should now have enough play in the cable that you 
    can remove it upwards and out of the cam.  Also, remove
    the cable housing from the metal holder.

14. At the bottom of the TB, find the electrical connector.
    Remove it by finding a squeezing the metal spring clip
    and pulling.

15. Using the allen wrench bit, loosen the four bolts which
    mount the TB to the engine.  Carefully remove these and
    lift the TB out.  NOTE: the bracket which holds the 
    throttle cable grommet is attached to the TB by the two
    right screws, so it will also come out.  NOTE: there
    is a gasket between the TB and engine; it will most
    likely remain stuck onto the engine.

16. Remove the TB gasket from the engine.

17. Make sure the modified TB is clean, no metal shavings
    in it, etc.

18. Put the four bolts onto the new TB... don't forget to
    also put the throttle cable bracket on.

19. The stock throttle body has a black rubber grommet on
    its air intake.  This is the grommet that mates to the
    air plenum.  Remove this grommet and install it onto the
    modified TB. (This grommet may help to keep the bolts
    from falling out completely, as I think it gets in
    their way... but don't count on it.)

20. Install the new gasket (provided from Schaumburg) onto
    the new TB.  One of the more challenging tasks is to
    keep the gasket aligned and not loose it or the bolts
    while installing!

21. Install the new TB.  I pulled the 4 bolts out until just 
    a thread was showing through the gasket, then positioned
    the TB and got each of the bolts started.  Tighten the
    bolts snugly... I asked Schaumburg about torque specs,
    but they just said "we just snug 'em up".

>From this point on, everything goes in reverse.  You might
want to connect the throttle cable and have someone sit
it the car and hold the gas pedal all the way down, while
you verify that the throttle body is fully opened (cam has
turned as far as it can clockwise).  You can adjust the
cable some... just to the right of where the cable housing
is held by the throttle cable bracket (the one that came off
with the TB), you'll see a U-shaped metal clip.  You can
remove this clip and reposition the cable a bit, then
re-insert this clip.   


If you are installing an air filter, do it before reattaching
the air hose.

1. Pull of the cowling piece that covers the air box.

2. Remove the flexible part of the air hose at the front left
   of the car... then remove the piece to the left of it,
   that leads down into the air box.

3. Unclip the 4 clips that hold the air filter cover on to
   the air box.

4. Move the airbox cover enough so that the air filter can be
   removed.  Remove the filter, put in the replacement, and
   reverse the process.