944-S2 Throttle Body Service Instruction Worksheet
Introductory Notes - this kit is designed to support resealing of your Porsche 944 S2 throttle body (TB). Carefully read
the text in the following pages and become familiar with the contents of this worksheet before performing the throttle body
overhaul. As with any rebuilding process, many judgments must be made along the way. While typical problems have been
highlighted within these pages, judgments pertaining to assembly re-use & operations are the responsibility of the mechanic
performing this work. Distributors of this kit shall not be held responsible for damage resulting from poor judgment.
Notes on Cleaning and Inspection - Once disassembled, place the throttle body (TB) parts in a cleaning
solvent. Soak parts long enough to remove foreign materials. Use a stiff bristle brush. Do not use any abrasives to
clean TB parts. Do not insert wire to clean out passageways. Wash off in suitable solvent. Clear out all passageways
with compressed air and check to ensure thorough cleaning of obscure areas. Inspect all parts for damage and stripped
threads.
CAUTION - Do not soak parts containing rubber, plastic and electrical parts in cleaning solvent.
Preliminary Notes




Cover opening on intake manifold after TB is removed.
The idle stop screw need not be removed for this procedure.
Adjustment of the idle stop screw requires detailed engine-running procedures. Please consult the Porsche workshop
manual for these procedures.
Before disassembly, pay particular attention to the torsion springs and how they are positioned. . These springs are
often the point of some confusion. There are several photos of the springs within these pages to help with
assembly but basic familiarity with configuration and operations is very important. Also provided within these
pages (see Figure 1) is a detailed sketch. This effort was good will gesture by Chris Pacitto.
Removal of the TB from engine
1.
2.
3.
4.
Remove the air filter box and snorkel, Air Flow Meter and other parts in order to access the throttle body.
Disconnect the Throttle Position Sensor (TPS) electrical connector and remove the 4 cap screws used to mount the TB
to the intake manifold.
Disconnect the vacuum lines, throttle spring and hoses as needed to separate the TB from the engine.
Remove the TB to the workbench.
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Figure 1. Throttle Body Parts (courtesy of Chris Pacitto)
Disassembly of the Throttle Body
1.
Before you begin, you may wish to scribe a witness mark on the Throttle Position Sensor (TPS) mounting ear to use as
a reference during re-assembly. Carefully remove the 2 Phillips screws that secure the TPS and separate the TPS from
the TB. Remove the TPS O-ring and replace it with one from the kit. Set the TPS aside for later re-assembly. Also,
remove the large TB-to-Intake flange O-rings (inner and outer).
2.
The two images below highlight the four points where the two torsion springs connect with the TB. Note that when
installed they have 15 and 26 coils (when removed these numbers are less by 2 and 2-1/2, respectively). Getting these
springs back into this position is the only difficult part of this TB reseal. Carefully follow the pictorial sequence to see
how this is done. Note: it is best to count and note the number of coils on the longer spring, we have seen a few
instances where the coil count was 27 and you may wish to re-assemble using the 27 count.
3.
4.
5.
Remove the nylock nut and serrated washer – the nut and serrated washer can be discarded. Also note the
two outer connection points for the torsion springs.
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6.
7.
8.
Use needle-nose pliers to the end points of the springs and release them from the levers. This will release each spring,
allowing them to unwind by approximately 2 turns.
Use pliers to rock, and then remove the throttle shaft lever.
9.
10. Remove remaining lever and both springs. This throttle linkage assembly can be disassembled for cleaning. The e-clip
can be removed and the pivot pin can be cleaned. The e-clip can be replaced with a circlip provided in the kit but the
washers must be re-used.
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11.
12. The next two images show the configuration of the parts beneath the springs. Clean and retain these parts.
13.
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14.
15. On the TPS side of the TB, remove the shaft circlip (snap-ring) using small picks or other pointed tools.
16.
Next is a thin washer (beneath the snap-ring), clean and retain this washer for re-installation.
17.
Using a felt tip pen or an awl, make an indexing mark on the throttle plate, this mark will help to re-orient the plate
during assembly. Remove the oval head screws and with the shaft rotated to wide-open-throttle (WOT) position,
remove the throttle plate. These screws can be stubborn due to the end of the screw being deformed; a rotary file or
Dremal tool may helpful. Inspect the shaft for any burrs and, if found, use a rotary file or Emory cloth to smooth the
shaft. This will make the shaft easier to extract.
18.
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19. Extract the shaft out of its bore – pull it out the side of the TB that is opposite the TPS. Clean and inspect the shaft, use
a file or emery cloth to remove sharp edges that might otherwise damage the new seals during re-installation.
20.
21. Remove the thin flat washer beneath the snap-ring’s groove and inspect the bore. Within this bore (both sides of the TB)
there are roller bearings. These bearings were originally equipped with an integrated wiper seal. The seals deteriorate
quickly and many times are dried, broken and unrecognizable. Use a pick to clean out the residue. With the old seal
residue out of the way, the bearing cage can then be moved back and forth by about 2 mm. Slide the roller bearing cage
outward. This will create a small groove, into which you can insert the new oring seal during reassembly.
22.
Re-assembly of the Throttle Body
Note: begin re-assembly only after parts have been cleaned and inspected.
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1.
Use the image above to identity the various o-rings needed. The shaft o-rings are unlike others in the kit and have
a nearly square cross-section. Insert new, shaft o-rings into positions where the bearing seals were removed. Be
sure each o-ring is fully seated. Installation hint: a common pencil stub can be helpful positioning the shaft o-ring,
see the cut-away image above.
2.
Inspect the shaft for burrs or sharp edges that can damage the new o-rings. Use a small file or emery cloth to dull
the machined edge of the shaft (see photo). Apply a liberal coating of automotive grease to the shaft, this will help
prevent cuts or damage to the new o-rings when the shaft is inserted into the bore.
3.
Gently insert the shaft into the TB (inserts from the side opposite of the TPS mount). Use a gentle rocking motion
and steady pressure to avoid damaging the o-rings. When done the shaft should have only a small amount of
rotating drag due to the new seals. If significant drag is apparent, a small amount of WD-40 or thin machine oil
applied to the throttle shaft/bore/seals area can help the seals to seat and may be needed to allow the shaft to rotate
freely.
4.
Install the thin washer and circlip to secure the shaft in the bore. The clip can be difficult to work with and the
proper tool is not available to many mechanics. This simple trick might help - this sheet-metal screw is wedged
into the clip’s tang just enough to open the clip. Once opened, it can be slipped over the end of the shaft. The
screw can then be removed and the clip can be worked into position. Ensure the clip seats in its groove.
5.
Insert the disk and secure it with the new screws. Check for smooth operation and seating of the plate when
placed in the idle position. Thread locker must be applied to the threads of the new screws.
6.
Check for binding and even mating in the area of the disk’s edge and the main bore of the TB. Any sticking in the
disk may result in idle problems later. Rotate the shaft so that the heads of the disk screws are down. This is the
idle position of the disk.
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7.
8.
Position the springs on the throttle shaft and pivot stud and be sure the underlying parts are in place.
9.
Assemble the linkage onto the shaft and pivot stud with its attaching parts. For now, we are not concerned with
winding of either spring; just get them in the proper general position. Both the nylock nut and shaft nut should be
finger-tight.
10.
11. Use needle-nose pliers to wind and position the longer 26-coil spring. Ensure it is wound so that it has 26 coils.
12. Note: getting the springs back into their respective wound positions can be a real problem – especially for the
smaller, 15-coil spring. This is easily done though with an assembly trick. Basically the trick is to first insert and
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secure the shaft. Then manually wind the 15-coil spring part way with simple tools such as needle nose pliers.
Finally, use a short piece of lockwire to hook the end of the 15-coil spring and pull it around the shaft and into
position. The steps below will demonstrate this method.
13. Open the disk from its idle position and insert a paper towel or small rag to hold it in this position.
14.
15. Before going further, study the sequential photos below – use these photos as a guide for getting the 15-coil spring
properly wound.
16.
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17.
18.
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19.
20. The serrated washer and stainless steel nut can also be tightened to secure the throttle lever. Do not over-tighten
the nut or the shaft will be twisted (damaged) - approximately 6 inch-pounds is sufficient.
21. The nylock nut can also be tightened, securing the throttle linkage assembly.
22. Ensure the TPS o-ring is in place on the TPS and position the TPS on the TB casting. Position the TPS as pictured
above. Reference the scribed witness mark, made during disassembly, and secure it using the 2 stainless steel hex
cap-screws and washers.
Installation of the TB
1.
2.
3.
4.
Place the new TB-to-Intake o-rings on the TB casting.
Position the TB so that the throttle cable can be re-attached to the throttle cam.
Once attached, secure the TB to the intake manifold using the 4 stainless steel cap screws and washers. Tighten these
in an x-pattern.
Install the remaining attaching parts. Inspect the throttle cable through all positions of operation closely. Broken cable
strands can cause sticking throttle conditions.
Venturi
Included in this kit is an o-ring for the venturi. The venturi is a small, y-shaped device and is located near the intake
manifold. It is not available on all models of the 944. The venturi can be removed from its connecting hoses and then be
separated into its two parts. Once separated, the o-ring can simply be replaced and the parts re-assembled.
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