[Author Prev][Author Next][Thread Prev][Thread Next][Author Index][Thread Index]

FAQ so far...

 Below is the first crude draft of an Audi FAQ, which I started an 
 embarrassingly long time ago. I think I mentioned some feeble excuses
 about workloads in a mail I sent out last week.

 Anyway, here it is. Anyone who wants to improve upon or add to it is
 very welcome. If anyone wants to fill in some of the blanks, please
 email me your text and I'll stick it in. 

 Some of you will recognise your own text in here  I hope I credited
 all of the text I swiped from the archives.

Alasdair Mackintosh                                 Shape Data, EDS Unigraphics
mackinto@ug.eds.com                                   Parker's House, Regent St
+44 1223 371608                                         Cambridge, CB2 1DP, U.K.

                        Frequently Asked Questions
                                for Audis

                          Very crude first draft

                          by Alasdair Mackintosh

    DISCLAIMER: Although we believe the information in this FAQ to
    be correct, the authors accept no responsibility for any losses
    or damage that may result from using this information. 

Section 1 - General Questions

  1.1 Who makes Audis?
    Audi was originally formed in Germany in 1910, by August Horch. ("Audi" is 
    the Latin version of his name, which means "hearken" in German.) 

    In 1932, it merged with three other German car companies to form Auto
    Union. (The four linked circles of the Audi logo symbolise this
    merger.) In 1963 the company was renamed Audi, and merged with
    Volkswagen to form "Volkswagen Audi Geselschaft" (VAG).
    VAG also owns SEAT, and Skoda. These cars are not covered here.

  1.2 Are they reliable? Are they good value?

    Generally speaking, yes. The powertrain and other basic parts of the
    car are very reliable, and rust is rarely a problem. However, the
    luxury add-ons are less reliable, and things like electric windows,
    powered sunroofs, and the like can often develop small nagging
    Servicing costs are quite high. Offical parts from dealers are
    expensive, although there are cheaper alternative sources.
    Depreciation is fairly high. This is partly because of the parts &
    servicing costs,  This makes used Audis excellent value.  Leasing
    might be more sensible if you are after a new car, unless you plan to
    keep it for some time.

  1.3 What is a Quattro? What is an Ur-Quattro?

    'Quattro' was the name of the first Audi to use permanent all-wheel
    drive (AWD). Following the success of this model, Audi began to
    produce AWD versions of other models, and added the 'Quattro'
    designation to them, thus producing the '4000 Quattro', the 'Coupe
    Quattro', and so on. To distinguish the first Quattro from these other
    models, Audi engineers began to call it the 'Ur-Quattro', 'Ur' being a
    German prefix meaning 'original'.

    Throughout this FAQ, the term 'Quattro' will be used for any Audi with the 
    AWD system, and the term 'Ur-Quattro' will be used for the original Quattro 
    Turbo Coupe. 'Quattro' may be abbreviated - e.g. 200Q = 200 Quattro.
    (See Section 2 for details.) 

  1.4 What was the 'unintended acceleration' business all about?

    In the mid-80s, there were several incidents in the US where Audi 5000s 
    with automatic transmissions displayed 'unintended acceleration', in which 
    idling cars would suddenly surge forward, even though the driver was trying 
    to brake. A "60 Minutes" TV documentary supposedly demonstrated this 
    happening on a test car.

    What they didn't tell you on TV was that the test car had been rigged.
    Nor did they tell you that one of the drivers involved addmitted to
    the police after the accident that she had been pressing the
    accelerator instead of the brake. The actual cause of the problem was that 
    the pedals on the Audi were closer together than on many American cars, 
    thus causing some people to hit the wrong pedal (and to press it harder the 
    faster the car accelerated.)

    [Are there any references on this?]

  1.5 Further sources of information.

    1.5.1 The Quattro mailing list.

      This list is for the discussion of all types of Audis (not just
      Quattros.) To subscribe, send email to majordomo@swiss.ans.net, with
      the line 'subscribe quattro' in the body of the message.

    1.5.2 The Quattro archives

      This FAQ, along with various articles and images, can be obtained 
      via Gopher at swiss.ans.net.

    1.5.3 AudiNet

      There's a new WWW page at http://ursa12.cs.utah.edu:5000. This contains
      various pictures, and links to other sites.

    1.5.4 The VW archives

      These are available from ftp.lap.umd.edu ( by anonymous
      ftp, in the directory 'vw_archives'. This contains the VW FAQs, plus
      various supplementary articles. A lot of the information here is
      relevant to Audis.

    1.5.5 rec.autos.vw

      This usenet group is primarily for discussion of VWs, but Audi issues
      are sometimes discussed as well.

    1.5.6 Magazines

      US publications. [???]

      UK publications. 
          "VW Audi Car" 
          Autometrix Publications
          Market Chambers, High St
          Teddington, Beds, LU5 6BY
          Tel: 0525 875582

Section 2 - Model Details and Buyers' Guide

  This section lists the various Audi models availiable, with a brief 
  description of each. It is also a buyer's guide, listing the various pros and 
  cons of each model, and a list of potential problems to watch for if buying 
  a used Audi.

  Note that there are a wide range of options for each model, and this guide
  can only be a summary.

  2.1 Where can I find Audis advertised?

    In the US: Subscribe to the 'quattro' mailing list.
               [There must be others?]

    In the UK: "VW Audi Car" magazine has a classified section each month.

  2.2 General notes

    Until the introduction of the V6 and V8 engines all Audis were powered
    with either a four or five cylinder inline engine. The four cylinder
    model came in 1.6 or 1.8 litre displacements, and in carburettor or
    fuel injected versions. (Only the FI model was availiable in the US.)
    A 2.0 litre version was introduced in 1991. Original version was 8
    valves, a 2.0 litre 16-valve version was introduced on some cars in

    The five-cylinder engine is based on the four-cylinder block, and is 
    availiable in 2.0, 2.2 and 2.3 litres. Both turbocharged and normally 
    aspirated versions are available. Early versions has 10 valves - a 20 valve 
    version was introduced in 1988.

    The 2.8 litre V6 was introduced in 1991.

    Unless otherwise stated, all models are availiable in front-wheel drive or 
    AWD (Quattro) versions. The AWD versions are only availiable with a manual
    gearbox. (Except for the V8, and late model 100s.) This is caused by the 
    layout of the driveshafts, which precluded an automatic gearbox.

    [Diesel models are not covered here. I don't know if anyone on the quattro 
    list has a diesel, or how popular they are in the US.]

  2.3 What points should I look for on a used Audi?

    The CV (Constant Velocity) joints that drive the front wheels can
    cause problems.  Look underneath at the rubber boots on the joints. If
    these are split, dirt has probably gotten in to damage the joint. Try
    driving slowly with the steering on full lock - a regular clicking
    indicates a damaged joint.

    Audis resist rust, so any rust you find may point to accident damage - 
    check panels carefully for colour and alignment if you suspect this.

    Check all electrical items - windows, sun roofs, etc.

    On Quattro models, check that the differential locks engage smoothly. Some 
    rumble from the drivetrain is normal, but it shouldn't be excessive. Also,
    check the seals on the rear differential for any leakage.

  2.4 Model summary 

  quattro: 1980-1991 (1982-1985 in the US)

    The 'Ur-quattro', or 'Quattro Turbo Coupe'. Based on the Coupe (see
    below) , with a turbocharged 5-cylinder engine, and permanent AWD.
    European models had 200 bhp, US ones only 160. (Note that the Ur was
    only imported into the USA until 1985.) The main external difference
    from the regular coupe is the wider wheels, with flared arches.

    Upgraded in 1984, with improved suspension, digital instruments and ABS.
    Second major revision in 1988 added torsen diffs, improved torque, 
    water-cooled turbo. Final version in 1990 had 20-valve head, with 220 bhp.

    The Quattro dominated world rallying when it was first introduced. These 
    are terrific cars (although the US version is a bit underpowered) with 
    amazing grip and traction. However, they are complex machines, and less 
    reliable than other Audis. They are also hard to work on - fitting the 
    engine and turbo into the Coupe's engine bay leaves little spare space.

    Buying: Make sure there's a proper service history. Check all electrics,
    as the wiring loom isn't as heavy-duty as it should be. Check the exhaust 
    manifold for cracks - this is a common Ur fault, caused by the weight of
    the turbo on the manifold.
  Audi 80/Audi 4000 

    Four-door saloon, with 4 or 5 cyl engine. ('4000' is American
    designation.) New version introduced in 1986, with less angular
    styling - now called '80' in USA as well. Latest version introduced in
    1991, with imporoved rear suspension design, new engine range
    (including v6), much larger boot/trunk. Estate/Station Wagon
    introduced in 1993.

    The basic model. Competent saloon, although the boot/trunk is small on 
    pre-91 models. No turbo versions.
  Audi 90

    Basically the same as the 80, but with a higher level of trime & equipment.

  Audi Coupe

    Based on the 80/4000 but with only 2 doors, and a sloping rear window.
    Most models had a 5-cyl engine, although a 1.8 4-cyl was also
    availiable. Don't confuse the Coupe Quattro with the Ur-Quattro. (See
    New 3-dr version introduced in 1988. Revised in 1991. 2.8 litre v6 

  Audi 100/Audi 5000

    Foor door saloon and estate/wagon, with 4 or 5 cyl engine. ('5000' is
    the American designation.) Interior and instrmumentation revised in
    1988. New version in 1991, with new body shape, new engine range
    (including v6), now called '100' in USA as well.

    Larger, more luxurious than the 80. Used prices are very attractive.

    Buying: Check the power steering rack and pump for leaks, as these units run 
    at high pressure.

  Audi 200

    Basically the same as the 100, but with a higher level of equipment.

    Buying: On the 200Q, the original inboard front brakes tended to
    overheat, and the disks would warp. They also made the steering feel
    heavy, because of the high unsprung weight. Customers who had problems with
    these brakes could get them (and the front suspension) replaced under 
    warranty. It's a good idea to check that this has been done with a used 

  Audi S2

    High-performance version of the new coupe, introduced in 1990. 20v turbo, 
    with 220 bhp amd Quattro AWD. Successor to the Ur-Quattro. Currently not 
    availiable in the USA.

    There is also an S2 Estate, based on the 80Q Estate. Finally, there's the
    RS2, an S2 Estate upgraded by Porsche, with new brakes and suspension, and 
    300 bhp. If you buy one of these, let us know what it's like...

  Audi S4

    High-performance version of the 100, introduced in 1992. 20v turbo, 
    with 220 bhp amd Quattro drive train. 6-speed gearbox.

  Audi V8

    Four-door saloon, with V8 angine, 4-sp automatic gearbox, and Quattro AWD 
    system. Introduced in 1990 with 3.6 litre engine, upgraded to 4.2 litres in 
    1991. (1991 version also offers optional manual transmission.) The V8 has 
    computer-controlled differentials, rather than the purely mechanical system 
    of other Quattros.

    Outwardly similar to the 100. Luxury-car refinement, with sports-car handling. 
    Expensive to buy and maintain. 

    Buying. The V8 had the same internal calipers as the 200Q (see above.) 

  Audi A8

    Aluminium-bodied luxury saloon, with V8 engine, introduced in 1994. 
    Designed to scare BMW and Mercedes.

Section 3 - Quattros

  AWD stands for All-wheel drive, 4WD for 4-wheel drive, the difference
  being that AWD implies permanently engaged four-wheel drive and 4WD
  for part-time manually selected four-wheel drive.  The car industry
  usually uses these definitions but not in all cases.

  4.1 Was Audi the first to produce an AWD road car?

    The Jensen Interceptor FF was the first, but it was a fairly complex
    system, and the car wasn't a great success. The Quattro was based on
    VW's Iltis off-road vehicle, which was a proven, and robust

  4.2 How does the Quattro system work?

    The first Quattros had three differentials - centre, rear and front.
    The centre diff allows the front and rear wheels to turn at different 
    rates, which they need to do when the car corners. (Most 4WD vehicles don't 
    have a centre diff, so they can't be used at any speed on the road.) A 
    hollow driveshaft in the gearbox was used to transfer the power to the 
    rear. (This is why Quattro models were only available with 5-sp 
    tranmissions, until the layout was redesigned for the V8.)

    The Quattro setup is entirely mechanical, unlike some systems (eg Mercedes 
    4-matic) which engage AWD when wheelspin is detected.

  4.3 What are the differential locks for?

    Conventional differentials allow the two shafts to spin at different
    speeds, but they divert more power to the faster shaft. Thus on a
    Quattro, if the right rear wheel started to spin, the centre diff
    would divert power to the rear, and the rear diff would divert it to
    the right, thus depriving the other three wheels (which actually have
    grip) of any power. To deal with this, you can lock the diffs, forcing
    the output shafts to go at the same speed. Centre and rear diffs can
    be locked independently.

    Diff locks should only be used if the wheels are likely to slip - using 
    them on normal roads puts a strain on the transmission.

  4.4 What is a Torsen differential?

    A TORque SENsing differential, which splits torque, sending more to
    the *slower* shaft. This is a purely mechanical design, and it avoids
    the need for diff locks. Torsens were introduced on Audis in 1988.

  4.5 What are the advantages and drawbacks of Quattros?

    They are slightly heavier, and slightly more complex than FWD cars. If you 
    drive gently, and in fine weather, they're probably not worth it. In wet or 
    wintry conditions, though, the extra traction makes a big difference.

  4.6 How do you drive a Quattro?

    The handling is basically neutral, although they will understeer if pushed 
    very hard. (Hairy rally-driver types like to lock the rear diffs to induce 
    powered oversteer - this is not recommended unless you know what you are 

    Don't assume that Quattros can never lose grip. Remeber that 4 multiplied 
    by zero is the same as 2 multiplied by 0.

  4.8 Doesn't Traction Control make AWD obsolete?

    Traction control works by limiting the amount of power you can apply to the 
    wheels. AWD allows you to apply more power, by spreading it over four wheels 
    instead of two. Which do you prefer?

Section 4 - Improving your Audi

  5.1 Increasing engine power - non-turbos

    Options include performance exhausts and air filters, polishing and porting 
    cylinder heads, performance cams, etc. The VW performance FAQ covers this 
    area in more detail, and the information is relevant to non-turbo Audis.

  5.2 Increasing engine power - turbos

    Basically, you want more boost. Here's how the system works:

    The wastegate contains a diaphram and a spring to allow control of
    boost. The spring is a static/failsafe boost control mechanism, while
    the upper portion of the diaphram allows "tweaks" by the computer. The
    wastegate spring "balances" against pressurized air exiting from the
    turbo. This is the only boost control non-computer controlled cars
    have. The computer monitors boost on the downstream side of throttle.
    If the computer thinks the boost is too low, it switches a valve
    (frequency valve in Audi lingo) to allow boost pressure to be applied
    on top of the wastegate diaphram.  This has the effect of making the
    wastegate spring appear stronger. If the boost gets too high, the
    computer switches the frequency valve to vacuum and lowers the
    pressure on top of the wastegate diaphram. This has the effect of
    making the wastegate spring appear weaker. Where do you get vacuum
    when a turbo engine is running at full boost?  Only one place; the air
    intake to the turbo (just like a vacuum cleaner).  It's important to
    note that there is pre-throttle boost, and post throttle boost.
    Application of the correct "boost" at the proper place is essential
    to safe operation.

                            Wastegate spring                                  
                           /                 computer controlled valve        
  WASTEGATE               /           +-----+/         C = A  or C = B
          +-------====---/----+       |     +------------------------+        
          |       ----  /     |  <->  |   A +----------------------+^|boost at
          |push|  ---- /      +-------+     |           <---       |^|  open  
          |down|  ----        +-------+C    +----+                 |^|throttle
          |   \ / ----        |       |   B +--+v|  +------------.-+ +------  
          |    v  ----        |       +-----+  | |  |  > > > >  /    to intake>
          |_-----------------_|                |v|  | ^ +------.------ -----  
         /|        ||         |                | |  | ^ |      |      |       
diaphram/ |        ||         +---------------------+ ^ | throttle    +------>
          |        ||           < < < < < < < < < < < ^ |          to sensor in
          |      | ||  ^      +---------------------+ ^ |            computer 
          |      | ||  |      |                | |  | ^ |                      
          +----- v ||  | up --+       constant |v|  | ^ | Throttle valve      
             down  || less boost        vacuum | |  | ^ |                     
         more boost||                        \ |v|  | ^ |                     
                   ||               ||         | |  | ^ |Boosted air outlet    
                  /||    +----------||--------------+ ^ |                     
                 / ||    |  > > > > ||> > > > > > > > ^ |                     
boost regulator /  ||    | ^ +------||------------------+                     
                +--------+ ^ +      ||         | |  
                |            |   intercooler   |v|
                |  TURBO     |                 | |
  \             |  "AIR      |                 |v|
   -------------+   PUMP"    |                 | |
AIR INTAKE> >   >   >   >    |        constant |v|
   ---------+ +--------------+          vacuum | |
  /         |^|                              \ |v|
            |^+--------------------------------+ |

    Thus, in order to increase boost, you need a computer that will allow 
    higher boost levels. This can either be achieved by fooling the computer 
    into thinking that the boost is lower than it is, or by altering the 
    computer's boost map.

    Note that running with higher boost will increase engine wear, and oil/fuel

  5.3 Can I add a turbo to my car?
    Yes, but it's almost certainly not worth it. Even assuming there's space in 
    the engine bay, you'd have to modify a LOT of the engine's components if you 
    wanted to turbocharge it. Alternatively, you could add a complete turbo 
    engine (plus all the extras) from another car (assuming it will fit), but 
    that won't be cheap or easy. You're better off selling your existing car and 
    buying a turbocharged one instead.

    (For details on how it could be done, see the article "California Quattro" 
    in "VW & Porsche" magazine, Feb 1988. There was also a kit made by Callaway 
    Turbosystems, mentioned by "VW & Porsche" in their "Project Audi Coupe" feature 
    that ran from December 1985 to February 1987 issues.)

  5.4 Improving handling

  5.5 Improving brakes

  5.6 [Anything else?]

Section 5 - Troubleshooting

    6.1 Engine problems

      6.1 The engine rattles when idling.

      If the there's a ticking sound is coming from the top of the engine,
      its probably the hydraulic tappets/lifters (Aug '85 models or later.)
      These tend to rattle when cold - to test them hold the engine at 2500 RPM 
      for two minutes. If they're still tapping, they ought to be replaced.

      [Can bad lifters ruin your engine?]

    6.2 Drivetrain

    6.3 Miscellaneous funny noises

    6.5 Handling problems

        [Steering wander, vibration, brake judder, ABS lights doing
        funny things.]

    6.5 Electrical problems

      6.5.1 My 'upshift' light has gone out - what should I do about it?

      This is the little arrow on the dash that come on to indicate that you
      should be in a higher gear. It's triggered by vacuum, so if it's not 
      working it may indicate a vacuum leak somewhere.

      6.5.2 My temperature guage isn't working.

Section 6 - Maintenance and Repairs

    [Insert disclaimer about this information not being guaranteed.
    Advise readers not to attempt anything they don't feel competent
    to do. Some basic safety advice.]

    [Note that I was intending this as a supplement to the manuals,
    and to point out pitfalls and shortcuts. E.g. the manual says
    "unscrew this" and the screw won't budge...]

  7.1 What manuals do I need?

  7.2 What tools do I need?

  7.3 Where can I get spare parts?

  7.4 Regular maintenance items

    7.4.1 What Oil & Oil filters should I use?

    Synthetic oils are more expensive, but resist heat better. There are
    two reasons why you might want to use them:
    1. In turbocharged engines to prevent oil from coking in the turbo
    from extreme temperatures.  

    2. In cases where one puts *lots* of highway miles in a non-turbo car,
    where oil changes every 3K miles are way too frequent and the use of
    synthetic oil allows changes more infrequently.
    On the whole,, a non-turbo car with average usage will benefit more
    from frequent 3-4K mile oil/filter changes with a good quality fossil
    oil than from synthetic. We would recommend synthetic oil for turbo cars

    Recommended oil filter is the original Audi filter, especially for
    turbos.  Audi oil filters have the anti-drain-back valve which
    prevents the oil from flowing back into the sump overnight. This
    ensures good lubrication for the top of the engine at startup and
    reduces hydraulic lifter noise. Oil filters made by Mahle, Knecht and
    Mann are excellent and are OEM suppliers to VW, Audi, BMW and
    Mercedes. (Avoid FRAM filters - they don't have the valves, and their
    internal construction is poor.)

    7.4.2 What Air filter is best?

    K&N FilterCharger is excellent. Costs more than the ordinary paper
    filter but lasts for the lifetime of the car. Needs cleaning and re-
    oiling every 30 to 50K miles depending on usage and dust conditions.
    It is free-flowing and claims to increase the horsepower by about 2
    hp, which is not noticeable easily, but turbos may benefit more from
    this.  The extended cleaning intervals spares you the trouble of
    removing and installing the air filter.

    Changing the filter is tricky on nearly all Audis, as the fuel distributor 
    sits on top of the filter housing. Normally you have to lever up the top
    cover until you can just pull the filter out. On some models you have to 
    remove the headlight assembly to gain access.

    7.4.3 Can I use ordinary power steering fluid?

    NO! You should only use the Audi approved hydraulic mineral oil in the 
    power steering hydraulics. Oridinary power steering fluid will damage the 

    7.4.5 What sparkplugs should I use?

    Bosch tri-electrodes. The triple electrodes increase plug life,
    resist fouling and according to one poster to the list, deliver a
    more consistent spark under high boost levels in the Audi turbocharged
    engines. They also make starting easier, and idling smoother.
  7.4 Engine/drivetrain

  7.5 Steering and suspension

  7.6 Brakes

  7.7 Electricals

    7.8 Climate control


Bill Samaras (samaras@wrksys.enet.dec.com)
Eliot Lim (eliot@u.washington.edu)
Zafer Mehmood (zm@mhcnet.att.com)
Ti Kan (ti@bazooka.amb.org)
Glen Powell (powell@interlan.InterLan.COM)