# 4000 & Coupe GT Buyers Guide & Modding Basics



## StormChaser (Jan 3, 2000)

*4000 & Coupe GT FAQ*

Welcome to the world of the "Type 85" Audi Coupe GT & 4000 quattro(based on the B2
platform). Yeah, it's not going to be the fastest thing around, but it will be fun. That 2.2 ltr inline 5 cylinder engine has GREAT low end torque. The 1987 CGT "Special Build" has the 2.3 ltr high compression "NG" engine which makes 130 hp. 
All 1987 CGTs in the USA came with a digital dash. You can tell whether your's is a Special Build based on some of the special things these cars had. 
Below is a list of all the special features that made the 1987 Coupe GT Special Build (aka 87.5 CGT)unique from the previous Coupe GT's
* High Compression (10.1:1) 2.3 Liter engine, with 130 bhp. (NG Engine Code)
* 4 wheel disc brakes, 10.1" rotors in the front, and 9.6" rotors in the rear. Girling 54 front calipers, and VW MkII style Girling rear calipers.
* The tirm around the windows and doors was changed from flat black to being painted the same color as the body. The mirrors and rear spoiler were also painted to match the car.
* The 87.5 only came in 3 available colors: Tornado Red, Alpine White, and Anthracite Black. If you happend to get a Black one, you were lucky very few were produced. White 87.5's came with optional "white painted" 16-spoke ronals.
* 092 transmission, rather than the traditional 093. The 092 was built using larger inner CV-joint hubs, like those used on the later Audi's.
* The 2.3 Liter NG, had it's own unique exhaust downpipe. 5 pipes to 2 larger pipes to 1 collector
* Audi added an auxiliary radiator in front of the engine, for additional cooling.
* 2.3 Liter, came with it's own unique intake manifold with larger runners, and the cylinder head was produced using larger valves for better performance.
* Power Door Locks
* Cloth interior was OPTIONAL.
You can identify the NG by the word AUDI stamped into the squared off intake manifold. The 2.2 ltr. KX/JT didn't say Audi on it and was rounded. If you happen to have a Special Build, count yourself as lucky. They are a rare beast, more rare than an UrQ. Only about 1,600 were produced, 856 imported into the USA, and who knows how many are left. 
There was a limted edtion CGT for 1986 that some confuse with the Special Build. It was actually called the Commemerative Edition and it was only an appearance package. It included a "Mouton" red leather interior, color matched mirrors/spoiler and a red digital dash...but no drivetrain changes. 
The CGT was voted as one of the best handling cars in America back in its day. It really handles better than almost anything else from the mid 80s, very tossable, lots of fun.
Mileage really matters little to the engine or transmission. There are plenty of 2.2s & 2.3s with well over 200,000 miles on them that still run like new and have never had major work done. But oil changes are very important to the car. If the oil isn't changed on time (3,000 miles, always use either a Mann, Bosch, or Audi OEM filter) the hydraulic lifters will tick like crazy. This is caused by lower oil pressure than is needed to fully pump up the lifters. Lifter tick is
considered normal for up to about a minute after start-up. The clutch should, if not abused, be good until almost 200,000 miles. The manual tranie itself
has Audi 5000 internals and is known for being next to indestructible. But beware of problems with the 3-spd auto (not avail for quattro) Basically a bad internal design causes the seal between the differential section and the automatic section to overheat, bake hard and then leak. The trans then begins to swap fluids in one direction or the other....90w gear oil gets into the automatic, or ATF gets into the diff. There was no real cure until the 1993 VW's came out with the redesigned trans.
There was/is an upgraded high temp silicone seal available for use in salvaging them. If the ATF looks golden, and/or smells like gear oil, you know what's going on. If you pull the diff side fill plug and 2 quarts of ATF run out...well, you get the picture.Overall the drive train is pretty much bulletproof on the CGT and 4000 quattro.
A loppy/unstable idle is also an common issue with these cars. It is usually caused by a faulty "Idle Stabilizer Valve." But the good news is that many
times, the valve isn't bad, it's just really dirty and so gummed up it cannot open/close fast enough to control the idle properly. The valve gets
gummed up because of its exposure to exhaust gasses looped back by the EGR. It's easy to clean, you just pop it out, spray it down with LOTS of throttle body cleaner (like fill it with the cleaner), scrub it out a bit with an old
tooth brush, actuate it a bunch of times (by intermittently applying 12 volts to it) then flush it again with even more throttle body cleaner,
repeat until you can see that it's clean and the cleaner comes out clear (instead of black). A rough but stable idle can be attributed to the need for a tune-up. First just try changing the plugs, if still rough, change the
cap and rotor button. If still rough change the plug wires (about $60USA for German wires with loom).
As far as things to look for, check the normal stuff. There are a few things that could be "issues." The window regulators (if equipped with power windows) are famous for failure. They use wire cable to lift the window.
These wire frequently fray and eventually fail from lack of lubrication. The fist sign of problems is slow operation. If they move slowly, or pause while moving, remove the regulator and lube the heck out of the wire and metal track and reinstall, keep your fingers crossed. if the regulators have already failed, there is no rebuild kit, they will have to be replaced. New
units from Audi are almost $500! But decent used ones can be found for under
$150. Aftermarket ones can be havd for around $125, but from what I've heard they have
problems with binding due to the unusual curvature of the window glass. Window switches and power mirror switches are also known to fail. If you are going through regulators on a regular basis, replace you felt window liner seals (the ones that the window ride up on. As they age and the soft felt part wears, friction increases greatly, overloading the regulator and eventually causing cable failure. Not hard or too expensive to replace. 
One note of caution, almost all of the powerequipment (differential locks (on the 4000 quattro), locks, cruise control, etc.) are vacuum operated. So, vacuum leaks may cause the accessories not to work. As I'm sure you know,vacuum leaks can be a pain to track down.
There really aren't many other CGT or 4000 quattro related issues. Look for things like
signs of accidents (that one got me, mine was cracked into in 1991, but the
repair is quality and the damage wasn't bad). If the shocks are bad, don't worry, they are pretty cheap. The most common upgrade is to put on Boge
TurboGas struts/shocks, which are about 15% stiffer than stock and have a lifetime warranty. They run about $250-$280 for a set of 4. Labor is a bit high at 5.7 hours for install (but most mechanics can get it done in 3
flat). Look for tired ball joints (play), and worn bushings (cracked). Most of the suspension bushings are pressed in and are pretty cheap to replace if bad. 
If you are in the USA, don't expect much from the DOT headlights. The stock DOT light use pathetic 9004 bulbs. No bulb is going to fix the bad lighting of the DOT lights and those ***** PIAA bulbs produce LESS light than a standard $5 clear bulb. It's just the design of the reflector and there's nothing you can do to fix it (other than converting to E-Code or European headlights). The stock DOT lights scatter the beam terribly, throwing a lot of it into the trees rather than onto the road. You can make some improvemnt by modding your stock light to allow you to use a 9007 hulb. You have to reverse the wiring for the high + power the ground and modify the headlight housing by breaking or filing down one of the little nubs. Then a 9007 bulb will fit and work properly. It provides a better low beam pattern while the high stays the same. My recomendation? Get some Euros. Or at least mod your lights to accept 9007 bulbs and RELAY them. You know that for every 10% drop in voltage you loose 30% of the light output, right? Well, test the voltage drop at you headlight connectors, you will see that they are only getting around 11.5 volts (the stock Audi headlight wiring is thin and LONG, a bad combo when it comes to maintaining voltage). That means you are loosing almost 45% of the light output. So if your bulbs are "rated" to put out 1,200 lumens of light (which is actually pretty high for a 9004 bulb most are closer to 1000), without relays they will only put out 660 lumens. That's a HUGE differnce! Now for REAL headlights, get youself a set of E-code (European) headlights. There are two kinds, one came on the Audi 80 (low level 4000) and another on the 90 (high end 4000). The 80 lights are H4s and the 90's are H4+H1. The 90's are far more expensive but when you hit the highbeam you get the highbeam filiment from the H4 PLUS an H1 bulb, which really turns night into day. The 80 lights are H4 only and are about 1/2 the price of the 90's. They still provide VASTLY better light than the stock DOT lights. 
CGTs are becoming increasingly rare in the USA and nice ones are getting very hard to find. Even ragged out ones are frequently selling at or above book value. Mine needed quite a bit of work, book value said $1,750 if it didn't need any
work, but the guy wouldn't go lower than $2,000. From what I've heard, many others have had to buy cars that need work for above book.
Now a little bit on modding your Typ85. Just like any naturally aspirated engine, you aren't going to get tons of power without switching to forced induction (turbo). But the 2.2ltr JT/KX engine does respons nicely to some modifications. The first mod you should do is advance the timing. If you run premium fuel all the time, you should be able to advance the timing to at least 12*. First set it to 12* and go for a drive. Do you hear any pinging? No? Try setting it to 14*, if you did hear pinging, back it off to 12* and test drive again. Basically, you want as much advance as possible without pinging. Other mods that will help: 272* cam, 2.25" exhaust (with 4000 quattro downpipe if it is a Coupe GT), larger throttlebody from the 2.3 NG/NF engine, port & polish, balance & blueprint, lightened flywheel, etc. Basically you can do anything you can do on any other NA engine. A properly modded 2.2 KX should get up to about 130-140 HP. A properly modded NG/NF will put out 150-155hp. I think that's plenty for the lightweight typ85... 
Now if you want REAL power, you eed to swap the engine. You can swap in the engine from a Urq, Turbo 5000, Turbo 200, etc. Basically any turbo I5. There are disadvantages to doing this: turbo lag, more things to go wrong, loss of AC, having to move the battery to the trunk.
Sorry for being so long winded. I hope all this info helps. http://****************.com/smile/emthup.gif 

_Modified by duandcc at 5:02 PM 7-21-2004_
_Modified by duandcc at 9:04 AM 8-27-2004_

_Modified by duandcc at 4:29 PM 4/28/2005_

_Modified by duandcc at 4:41 PM 4/28/2005_


_Modified by StormChaser at 7:55 AM 12/24/2008_


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## OptimusGlen (Feb 14, 2002)

*Re: 4000 & Coupe GT FAQ (duandcc)*

some usefull sites because I didn't see much in the FAQ...
new parts:
German parts and restoration http://www.gprparts.com
Blaufergnugen http://www.blauparts.com
2Bennett http://www.2bennett.com
Total Audi Performance http://www.tap1.com
used parts: 
Force 5 Automotive http://www.force5auto.com
Shokan http://www.shokan.com
junk yard search http://www.car-parts.com
Reference/Usefull:
Huw's site http://www.humanspeakers.com/audi
Audi fans http://www.audifans.com
Audi world http://www.audiworld.com
Audi Coupe GT specs... http://www.igdc.com/ejfluhr/audi/coupes.html


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## OptimusGlen (Feb 14, 2002)

*Re: 4000 & Coupe GT FAQ (VolksportGTi)*

the VW 8V adjustable timing gear will fit on the 10v I-5


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## OptimusGlen (Feb 14, 2002)

*Re: 4000 & Coupe GT FAQ (duandcc)*

Lot of CIS info, taken from http://www.auto-solve.com/mech_inj.htm follow the link and there are some pictures and diagrams as well. I took out the pics and diagrams to post on here.
Mechanical Fuel Injection
As this subject is large and fairly comprehensive it has been broken into the following sections:
1 Introduction and operational overview 2 The fuel tank 
3 The fuel pump 4 The fuel pump relay 
5 The accumulator 6 The fuel filter 
7 Systems pressure 8 The airflow sensor 
9 The fuel distribution unit 10 The warm up regulator 
11 The cold start injector 12 The auxiliary air valve 
13 The fuel injectors 14 System overview diagram 
NOTE:- whilst working on any fuel system, care and attention should be taken to avoid the petrol coming in contact with any source of ignition, this can include: hot engine components, High Tension (HT) sparks and smoking. 

Introduction
This form of mechanical fuel injection has been used on the internal combustion engine for many years. Mechanical fuel injection systems first saw light of day at the turn of the century, however the following 100 years has seen the system evolve from a very basic and almost crude fuel delivery system, to the recent mass produced versions of the Bosch K and KE Jetronic. The mechanical fuel injection system has recently been overshadowed by modern electronic injection, which enables the use of lambda closed loop control. The electronically modified Bosch KE also has this capability although it never achieved the popularity of the pure mechanical system. 
This following overview is a brief description of the system.

Bosch K Jetronic operational overview
The system may seem very complicated at first, but it can be broken down into specific areas and fault finding is therefore made easier. 
Fuel is delivered from the fuel pump to a metering (or fuel distribution) head and depending on the engine's temperature, the correct amount of fuel is delivered via the injectors to the engine. The injectors on this system spray fuel continuously in a fine atomised spray into the inlet manifold. 
Cold start and the warm-up period are also catered for by a cold start injector and a reduction in the control pressure. The idle speed is increased by the auxiliary air valve. 
The fuel pump will have the ability to provide a huge amount of fuel from the tank of which 99% will be returned. Due to the nature of this system, specialised equipment may be needed.


The Fuel Tank
The fuel tank is the obvious place to start in any fuel system explanation - unlike the tanks on early carburetor fuelled engines it is a sealed unit. This allows the natural gassing of the fuel to aid delivery to the pump by slightly pressurising the tank It may be noted that when the filler cap is removed, pressure is heard to escape. Filler caps are no longer vented as previously found. 


The Fuel Pump
This type of high pressure fuel pump is denoted as a roller cell pump, with the fuel entering the pump and being compressed by rotating cells that force it through the pump at high pressure. The pump is capable of producing a pressure of 8 bar (120 psi) with a delivery rate of approximately 4 to 5 litres per minute. 
Within the pump is a pressure relief valve that lifts off its seat at 8 bar to arrest the pressure should the filter, fuel lines or other eventualities cause it to become obstructed. The other end of the pump (output) is home to a non-return valve that, when the voltage to the pump is removed, closes the return and maintains pressure within the system, as illustrated in figure 6.1. 
The normal operating pressure within this system is approximately 5 bar (75 psi) and at this pressure the current draw on the pump is 5 to 8 amps. Fuel passing across the fuel pump's armature will be subjected to sparks and arcing, this on the surface appears quite dangerous, but the absence of oxygen means that there will not be an explosion!
Some systems operate a small lift pump situated inside the tank. The supply voltage to the pump in the majority of cases is 12 volts. 
Some systems do however operate at 6 volts, and see a higher voltage under cranking to pressurise the system faster. This voltage reduction is made possible by using a ballast resistor, which is then by-passed when cranking. 
The voltage supply to the pump is via the fuel pump relay. 
The Fuel Pump Relay
This type of relay is known as a tachometric relay, which means that it only responds and sends a voltage to the pump when the engine is cranking or running. The relay receives a signal from the negative terminal of the coil - this confirms that the engine is turning.
This type of relay is used as a safety device: if the vehicle is involved in an accident when there is a possibility of a fuel line being fractured, the engine will stop due to a lack of fuel, the signal from the coil stops and the supply voltage to the pump is removed. 
Typical fuel pump relay connections are as follows: 
Terminal Number Connection 
30 Permanent battery live 
31 Earth 
1 or 31b Coil negative 
15 Switched 'Ignition on ' voltage 
87 Output to fuel pump 
NOTE :- while the connections are correct for certain vehicles, the appropriate pins must be identified before testing. Certain relays also perform a pressurisation purge by allowing the pump to run for a second before shutting off, to prime the system. 
The location of the relay will vary between motor manufacturers and is in no set position. 
When fault finding or fuel pressure testing it will be necessary to have the pump running when the engine is stationary, this can be achieved by bridging terminals 30 and 87 with a small length of wire. For safety reasons it is good practice to insert a ten amp fuse into the bridging wire.
If the engine runs for a while but then stops, failing to restart for a few minutes, feel the relay to see if it is getting warm as this could be the faulty area. Bridging with the fused link wire will confirm the problem.
CAUTION :- do not be tempted to by-pass the relay by bridging between terminal 15 (switched live) and 87 (fuel pump) as this will start the car, but is potentially dangerous.
The Accumulator
The accumulator is the first of the components in the fuel system after the pump. This unit has an important role to fill in the operation of the Bosch K Jetronic system.
Its first job is to help smooth out any pulses in the flow of the fuel, this is achieved by passing the fuel through a series of baffles and into a chamber giving it slight capacitance and a much smother flow. Its other and possibly more important role is to maintain pressure within the system when the fuel pump has been switched off; this is achieved by the accumulator spring and diaphragm pushing against the fuel.
For the duration that the engine is running, the diaphragm will be against its stop within the spring's chamber. When the engine is stopped and all of the non-return valves close, the spring pressure against the diaphragm will maintain the residual or holding pressure and overcome any slight seepage. 
Within the data books for this system, it is shown that the critical time for maintaining these pressures, is between 5 and 20 minutes. After a journey, when the engine is switched off, the under bonnet temperature increases causing the fuel in the lines to heat and it attempts to evaporate.
Maintaining the pressure eliminates this problem and ensures a clean start when the vehicle has been standing with a hot engine. 
The Fuel Filter
Due to the extremely fine tolerances within the Bosch K Jetronic system, it is vital that the filter has excellent filtration properties without impeding the flow on the fuel. The filter is a large metal canister with different fittings at either end to avoid the unit being installed incorrectly and compromising its efficiency. A visual inspection of the filter is not possible but the current draw of the fuel pump, measured in amps, can indicate a blocked or obscured filter. 
The current can be recorded by inserting a multimeter in series with the circuit, the usual place to do this is to bridge the relay's terminal block. If however the relay is not easily accessible the fuse to the pump can be removed as this also provide a convenient place to measure the current. 
A typical current draw will generally be between 5 to 8 amps. The current recorded will be lower if the systems pressure is less than the quoted specifications and higher if the flow of fuel is restricted in any way, for example: a blocked filter or a damaged fuel line.
Systems Pressure
This is the pressure that is seen within the system between the fuel pump and the metering head. This pressure is determined by the primary pressure regulator, situated within the metering head.
When the required pressure is obtained, the plunger within the regulator lifts off its seat and excess fuel is returned to the tank. 
This system due to the nature of its operation will automatically compensate for different fuel demands under different conditions. For example if the fuel requirement is low at engine idle, the plunger will lift and return a greater volume of fuel back to the tank than when the demand is higher, when a smaller amount of fuel is returned. 
When the engine is switched off, the fuel pump relay looses the coil negative signals that energise it and the voltage to the pump is removed: this subsequent loss of pressure will cause the primary pressure regulator to close. This action subsequently blocks the return flow to the tank and helps the accumulator to maintain pressure in the system.
The systems pressure is determined by the tension of the spring reacting against the plunger, if a higher pressure is required, small shims can be placed behind the spring, changing it's effective length and increasing the pressure. A shim of approximately 2 mm will increase the pressure by about 10 psi 

Located within the pressure regulator is the transfer valve. This component is operated by the movement of the plunger and opens as the plunger moves off it's seat. The transfer valve's function is to block the return flow of fuel from the warm-up-regulator back to the tank, also helping to maintain residual or holding pressure. 
The Airflow Sensor
The airflow sensor, in most cases, is located on the air filter housing and is responsible for measuring the amount of air entering the engine. The sensor housing is conical in shape, into which the airflow sensor plate is fitted. The airflow sensor plate lifts as the throttle is opened by the incoming air. 
The amount of lift is proportional to the volume of air entering the engine. The shape and angle of the cone will determine this ratio. 
A neutral plate position is normally level with the bottom of the cone, this is adjustable by bending a small clip / spring that acts as a stop at the bottom of the unit. The purpose of this spring is to allow the flap to move beyond its neutral position to allow excessive pressure to escape if the engine was to backfire, passing a large volume of air back into the air filter housing. 
If the system did not have this facility the pressure could split or blow off the rubber air trunking. Any splits or ill fitting air hoses that allow unmonitored air into the engine require rectification. 
As the airflow lifts the sensor plate this subsequencially lifts the control plunger - the higher the lift the greater the amount of fuel delivered to the injectors. 
To adjust the fuel mixture a small 3 mm Allen screw is located within the airflow sensor; this alters the relationship between the sensor arm and the control plunger. Turning the screw clockwise enriches the mixture and vice-versa. It should be noted that the screw should be turned in very small increments and the Allen key should be removed before the engine speed is raised. 
NOTE :- Failure to remove the Allen key, before starting the engine, can result in damage to the airflow sensing unit. 
The Fuel Distribution Unit
This unit delivers the correct amount of fuel to the engine via the injectors referencing to the airflow sensor plate height. As the sensor plate is lifted with inducted air volume, the control plunger is lifted proportionately, exposing small slits within the fuel distributor's barrel assembly. The barrel assembly has a series (one for each cylinder) of small slits that are machined into the barrel, and it is through these openings that the fuel passes en-route to the injector. 
The width of these metered slits is only 0.2 mm across and it is this dimension, together with the plunger height, that determines the fuel delivery rate to the injectors.
At low engine speed the air volume into the engine will be minimal, this will only raise the plunger a small amount giving the requisite quantity of fuel for these engine conditions. As the throttle is opened and fuel demand is higher, the plate raises, which in turn lifts the plunger and a higher volume of fuel is delivered to the engine to match the air. The lift on the plunger will be proportionate to the air volume, this will however be exaggerated during the warm-up period when additional fuel is required by reducing the pressure acting onto the top of the control plunger. 
This pressure is called the control pressure (as it controls the lift of the plunger under different operating temperatures) and is determined by the warm-up-regulator. 
The Warm-up-Regulator
This simple device is responsible for controlling the amount of fuel delivered to the engine during it's warm-up period. The pressure acting upon the top of the control plunger varies depending on the engine temperature and provides an effective method of enrichment. 
The control pressure is tapped off from the primary pressure circuit in the metering head's lower chamber through a tiny restrictive hole which gives it the ability to differentiate between the two pressures. A flexible pipe then connects the control plunger gallery to the warm-up-regulator and returns back to the metering head to a connection next to the primary pressure regulator's transfer valve. This valve is in the circuit to close the fuel from the control circuit when the engine is off, avoiding the total loss of system pressure while the engine is stationary.
The internals of the warm-up-regulator are quite simple comprising an inlet and outlet port, a stainless steel shim, a bi-metalic heated strip and a spring. 
The input to the warm-up-regulator flows into a small chamber in the top of the unit, its return is through a small drilling and back to the metering head. By controlling this return flow it will cause a change in pressure acting on the top of the control plunger. With a cold engine the flow must be fairly free giving it a lower pressure. This will allow a higher lift of the plunger which in turn will enrich the mixture under these conditions. The free flow is obtained by the internal bi-metalic strip exerting a downward pressure on the spring which decreases the pressure acting upon the shim, this lower force allows the fuel to flow almost uninterrupted. 
As the bi-metalic strip is heated, by either it's heater element or natural heat soak from the engine, the downward pressure acting on the spring is gradually decreased, increasing the force of the spring, which in turn increases the control pressure. 
Typical cold engine control pressure will be as low as 1.0 bar increasing over approx. 10 minutes to around 3.5 bar. Some warm-up-regulators have a vacuum connection that will sense a drop in vacuum and lower the control pressure during these acceleration periods.
The voltage supply to the regulator is from the fuel pump relay, because if the ignition was on without the engine running, all enrichment would be removed as the bi-metalic strip would be heated prematurely and the driver would not benefit from the cold engine enrichment. 
The two pipes that connect to the warm-up-regulator have different sized 'banjo unions' to avoid them being connected incorrectly. The control pressures quoted are as an example only and reference should be made to the technical data as these pressures can be specific to the part number located on the unit's housing.
This unit will have a resistance value of approximately 20 to 26 Ohms.
NOTE :- it is important to disconnect the electrical connection to the unit before any pressure testing on the control circuit is performed as this will prematurely heat the bi-metalic strip and cold control pressures will not be available. 
The Cold Start Injector
To aid the starting of the engine an additional injector is located into the inlet manifold, this sprays fuel into the engine at systems pressure when the engine temperature is cold and the starter motor is activated. The length of time that this additional injector sprays is determined by the engine's temperature, seen by the thermo time switch.
The thermo time switch provides the earth path for the cold start injector via a heated bi-metalic strip, this heater is activated by a voltage from the starter motor. As the strip heats, over a period of approximately 8 to 10 seconds (when cranking only), the legs on the bi-metalic strip separate and the earth path is lost.
A warm engine will perhaps only require 2 seconds before the circuit is broken and a hot engine will already show open circuit. This simple circuit is to avoid the engine being flooded when cranking and the additional enrichment only given when essential, see illustration below. 
The Auxiliary Air Valve
This item is a device to aid the engine when cold by opening a small port to increase the engine's idle speed. The fast idle control is achieved by the port being held open by a bi-metalic strip that when heated by it's own heater element, or via natural heat soak from the engine, the port closes. The voltage supply to the air valve is the same as the feed to the fuel pump and the warm-up-regulator. If it is found that the idle speed will not reduce and that the speed is maintained artificially high when warm, clamp the rubber pipe between the air valve and the inlet manifold. If this action causes the engine rev's to return to normal, the fault is within a sticking auxiliary air valve. 
It is worth cleaning the valve, lubricating it and re-test it's operation. The internal heater element can also be checked for continuity using a multimeter. 
The Fuel Injectors
The injectors fitted to this system will open at a predetermined pressure and will spray a fine atomised 'mist' of fuel behind the inlet valve, waiting to be drawn in on the induction stroke. The fuel is delivered into the engine in a continuous spray and is not timed or pulsed as on other systems. The opening pressure of the injector is at approximately 3.3 bar at which point fuel is injected into the manifold; when the injector pintle opens this will cause the pressure to drop, subsequently closing the injector, which causes the pressure to rise once again and this will of course open the injector. This pintle vibration is called 'chatter' and helps to atomise the fuel before it's induction. 
When the engine is switched off the fuel pressure drops below 3.3 bar and the injector closes forming a fuel tight seal, helping to avoid fuel dripping into the inlet manifold. 
The spray pattern should be a conical shape and when clean and working efficiently, should emit a high frequency noise: this is the sound of the pintle 'chatter'.


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## Shawn M. (Oct 15, 2002)

wow good addition.
also look at http://www.20v.org for some good fix it and diagnostic info


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## Shawn M. (Oct 15, 2002)

rough suspension r&r
With wheels on the ground, loosen the center nut that holds the CV axle into the hub. Then loosen the lug bolts.
Jack up and remove wheels. Remove ball joint-hub clamp bolt, and remove it completely from the car (ball joint won't move with the bolt installed)
Hammer the control arm until the ball joint loosens and the control arm swings down.
Remove the top nut on the strut tube. There's a special 22 mm socket (o2 sensor socket) that you can use, but an impact wrench is much easier to use.
At this point the strut and hub assembly will drop down. Pull it off the CV joint.
Compress the spring, then you can take off the castle nut with a hammer and a drift pin or flat punch. Then you can remove the strut mount and spring. If you are changing struts then you will find a pipe wrench essential in taking off the strut caps that hold them into the strut tubes. You may need to apply WD40 and/or copious amounts of heat at this point,
I reccomend Sea Foam Deep creep for penatrant..works like a charm
to remove the back seat:
lower:
just grab and pull up
back rest:
two people, wiggle around then lift straight up, at top corners and center
air filter removal:
its easier to pull the pass. side headlight, but its possible otherwise..be patient and gentle


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## cjmiller (Jun 14, 1999)

*4000 & Coupe GT FAQ: driveshaft center support bearing replacement*

4000Q Center Drive Shaft Bearing Rweplacement part & Alternatives 
> From "Tools and Tricks" (http://www.humanspeakers.com/audi/tricks.htm) 

1: BMW part # for 4kq carrier bearing: Drive shaft carrier bearing BMW #26-12-1-209-532(includes bearing, bracket, rubber) 
2: I have found a source for the 4kq center driveshaft u-joint... Try calling Driveline Service in Portland, OR. (503) 289-2264. They have a joint made by GWB of Germany. P/N 287000600000. It is an exact fit AND it has the grease fitting on it. Price is a bit steep at $51 but it is an exact OE match. 
---------------
also:
http://www.urs4.com/technical/transmission.html
at the bottom.


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## 1badMKIrocco (Jan 18, 2002)

*Re: 4000 & Coupe GT FAQ (duandcc)*

What about RUST? Is there any certain areas that are prone to rust on the GTs? I've had a bunch of VWs and the older cars A1s Sciroccos and Rabbits all eventually met the boneyard due to Severe rust. The later A2 cars I've owned if they had any rust it seemed to be just minimal surface rust if any.


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## Shawn M. (Oct 15, 2002)

floor board on passengers side under sound deadening (just found this mess)
door jambs (on doors themselves)
around windshield (a pilar)
thats all there is on mine


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## [email protected] (Nov 13, 2004)

*Re: 4000 & Coupe GT FAQ (1badMKIrocco)*

I've had 2 CGTs with trunk leaks that have been impossible to find, as a result I've had 2 CGTs with rusty trunk floors...








Last summer I rust treated the trunk floor and then just went ahead and coated it with truckbed liner, that should at least delay the rust from starting again


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## MGaz (Aug 9, 2006)

*Re: 4000 & Coupe GT FAQ (StormChaser)*

with respect to modding.. what about a TSR head?
there was a guy in an audi/vw mag i saw pushing 170bhp+ out of his 2226KV 5pot coupeGT.
all he had was TSR head and fast road cam and a comp exhaust.


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## StormChaser (Jan 3, 2000)

*Re: 4000 & Coupe GT FAQ (MGaz)*

A lots of bad info is being passed around, so thought this deserved a bump.


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## dubbernutter (Feb 23, 2003)

*Re: 4000 & Coupe GT FAQ (StormChaser)*

Can't make it a sticky?!!
Added to my favorites


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## StormChaser (Jan 3, 2000)

*Re: 4000 & Coupe GT FAQ (dubbernutter)*

Its part of the FAQ that's already stickied.


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## dubbernutter (Feb 23, 2003)

*Re: 4000 & Coupe GT FAQ (StormChaser)*


_Quote, originally posted by *StormChaser* »_Its part of the FAQ that's already stickied.









oh yeah! Thats how i found it in the first place!!


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## MFZERO (Mar 13, 2002)

*FV-QR*

you can use 96+ A4/A6 2.8 quattro transmission mounts to replace the engine and rear differential side mounts. 
The rear differential mount you can use a mk1 rabbit mount with a prothane insert to stiffen things up on a budget.


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## Scorcher1 (Nov 8, 2011)

Does anyone know how/where to go about getting a new windshield for my '87 coupe GT? 

Or if it is interchangable with the 4000 or some other model?


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