Volkswagen Cars 2000-05

Spark Plugs 1

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A typical spark plug consists of a metal shell surrounding a ceramic insulator. A metal electrode extends downward through the center of the insulator and protrudes a small distance. Located at the end of the plug and attached to the side of the outer metal shell is the side electrode. The side electrode bends in at a 90 degree angle so that its tip is just past and parallel to the tip of the center electrode. The distance between these two electrodes (measured in thousandths of an inch or hundredths of a millimeter) is called the spark plug gap.

The spark plug does not produce a spark, but instead provides a gap across which the current can arc. The coil produces anywhere from 20,000 to 50,000 volts (depending on the type and application), which travels through the wires to the spark plugs. The current passes along the center electrode and jumps the gap to the side electrode, and in doing so, ignites the air/fuel mixture in the combustion chamber.



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Fig. Cross-section of a spark plug



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Fig. Close up of the electrode of a spark plug

Inspection



Check the plugs for deposits and wear. If they are not going to be replaced, clean the plugs thoroughly. Remember that any kind of deposit will decrease the efficiency of the plug. Plugs can be cleaned on a spark plug cleaning machine, which can sometimes be found in service stations, or you can do an acceptable job of cleaning with a stiff brush. If the plugs are cleaned, the electrodes must be filed flat. Use an ignition points file, not an emery board or the like, which will leave deposits. The electrodes must be filed perfectly flat with sharp edges; rounded edges reduce the spark plug voltage by as much as 50%.

Check spark plug gap before installation. Refer to the accompanying application charts for proper gap specifications. The ground electrode (the L-shaped one connected to the body of the plug) must be parallel to the center electrode and the specified size wire gauge must pass between the electrodes with a slight drag.


NOTE
NEVER adjust the gap on a used platinum type spark plug.

Always check the gap on new plugs as they are not always set correctly at the factory. Do not use a flat feeler gauge when measuring the gap on a used plug, because the reading may be inaccurate. A round-wire type gapping tool is the best way to check the gap. The correct gauge should pass through the electrode gap with a slight drag. If you're in doubt, try one size smaller and one larger. The smaller gauge should go through easily, while the larger one shouldn't go through at all. Wire gapping tools usually have a bending tool attached. Use that to adjust the side electrode until the proper distance is obtained. Be careful not to bend the side electrode too far or too often as it may weaken and break off within the engine, requiring removal of the cylinder head to retrieve it.

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Fig. Spark plug applications-2.0L (AEG, AVH, AZG, BBW, BEV) Engines



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Fig. Spark plug applications-2.8L (AFP) Engines



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Fig. Spark plug applications-1.8L (AWD) Engines



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Fig. Spark plug applications-1.8L (AWW and AWP) Engines



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Fig. Spark plug applications-2.8L (BDF) engine

Inspection & Gapping




NOTE
Multiple electrode plugs should not be cleaned and re-gapped, if worn or damaged they should be replaced.

Check the plugs for deposits and wear. If they are not going to be replaced, clean the plugs thoroughly. Remember that any kind of deposit will decrease the efficiency of the plug. Plugs can be cleaned on a spark plug cleaning machine, which can sometimes be found in service stations, or you can do an acceptable job of cleaning with a stiff brush. If the plugs are cleaned, the electrodes must be filed flat. Use an ignition points file, not an emery board or the like, which will leave deposits. The electrodes must be filed perfectly flat with sharp edges; rounded edges reduce the spark plug voltage by as much as 50%.


NOTE
Do NOT use a metal brush to clean the electrode on platinum-type spark plugs.

Check spark plug gap before installation. The ground electrode (the L-shaped one connected to the body of the plug) must be parallel to the center electrode and the specified size wire gauge (please refer to the Tune-Up Specifications chart for details) must pass between the electrodes with a slight drag.


NOTE
NEVER adjust the gap on a used platinum-type spark plugs or multiple electrode spark plugs.

Always check the gap on new plugs as they are not always set correctly at the factory. Do NOT use a flat feeler gauge when measuring the gap on a used plug, because the reading may be inaccurate. A round-wire type of a gapping tool is the best way to check the gap. The correct gauge should pass through the electrode gap with a slight drag. If you're in doubt, try one size smaller and one larger. The smaller gauge should go through easily, while the larger one shouldn't go through at all.

Wire gapping tools usually have a bending tool attached. Use that to adjust the side electrode until the proper distance is obtained. Absolutely NEVER attempt to bend the center electrode. Also, be careful not to bend the side electrode too far or too often as it may weaken and break off within the engine, requiring removal of the cylinder head to retrieve it.



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Fig. Inspect the spark plug to determine engine running conditions



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Fig. A variety of tools and gauges are needed for spark plug service



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Fig. Checking the spark plug gap with a feeler gauge



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Fig. Adjusting the spark plug gap



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Fig. If the standard plug is in good condition, the electrode may be filed flat-WARNING: Do NOT file platinum plugs



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Fig. The gap on this multiple electrode plug can be checked for wear; however, the plug should not be re-gapped. If worn, it must be replaced

Check the plugs for deposits and wear. If they are not going to be replaced, clean the plugs thoroughly. Remember that any kind of deposit will decrease the efficiency of the plug. Plugs can be cleaned on a spark plug cleaning machine, which can sometimes be found in service stations, or you can do an acceptable job of cleaning with a stiff brush. If the plugs are cleaned, the electrodes must be filed flat. Use an ignition points file, not an emery board or the like, which will leave deposits. The electrodes must be filed perfectly flat with sharp edges; rounded edges reduce the spark plug voltage by as much as 50%.


NOTE
Do not use a metal brush to clean the electrode on platinum-type spark plugs.

Check spark plug gap before installation. The ground electrode (the L-shaped one connected to the body of the plug) must be parallel to the center electrode and the specified size wire gauge (please refer to the Tune-Up Specifications chart for details) must pass between the electrodes with a slight drag.


NOTE
NEVER adjust the gap on a used platinum-type spark plugs.

Always check the gap on new plugs as they are not always set correctly at the factory. Do not use a flat feeler gauge when measuring the gap on a used plug, because the reading may be inaccurate. A round-wire type gapping tool is the best way to check the gap. The correct gauge should pass through the electrode gap with a slight drag. If you're in doubt, try one size smaller and one larger. The smaller gauge should go through easily, while the larger one shouldn't go through at all. Wire gapping tools usually have a bending tool attached. Use that to adjust the side electrode until the proper distance is obtained. Absolutely never attempt to bend the center electrode. Also, be careful not to bend the side electrode too far or too often as it may weaken and break off within the engine, requiring removal of the cylinder head to retrieve it.



Click image to see an enlarged view

Fig. Inspect the spark plug to determine engine running conditions



Click image to see an enlarged view

Fig. A variety of tools and gauges are needed for spark plug service



Click image to see an enlarged view

Fig. Checking the spark plug gap with a feeler gauge



Click image to see an enlarged view

Fig. Adjusting the spark plug gap



Click image to see an enlarged view

Fig. If the standard plug is in good condition, the electrode may be filed flat-WARNING: do not file platinum plugs

Removal & Installation



The spark plugs require replacement every 30,000 miles (48,000 km) on 1990-97 Audi A4 and VW Passat models, and every 60,000 miles (90,000 km) on 1998-00 Audi A4 and VW Passat models, depending on your style of driving. In normal operation plug gap increases about 0.001 in. (0.025mm) for every 2500 miles (4000 km). As the gap increases, the plug's voltage requirement also increases. It requires a greater voltage to jump the wider gap and about two to three times as much voltage to fire the plug at high speeds than at idle. The improved air/fuel ratio control of modern fuel injection combined with the higher voltage output of modern ignition systems will often allow an engine to run significantly longer on a set of standard spark plugs, but keep in mind that efficiency will drop as the gap widens (along with fuel economy and power).

When you're removing spark plugs, work on one at a time. Don't start by removing the plug wires all at once, because, unless you number them, they may become mixed up. Take a minute before you begin and number the wires with tape.

As the plugs are removed, keep them in order. A spark plug is a good indicator of how the particular cylinder is operating, and can help spot a potential problem.

  1. Disconnect the negative battery cable, and if the vehicle has been run recently, allow the engine to thoroughly cool.
  2.  
  3. Carefully twist the spark plug wire boot to loosen it, then pull upward and remove the boot from the plug. Be sure to pull on the boot and not on the wire, otherwise the connector located inside the boot may become separated.
  4.  


NOTE
On V6 and VR6 models, a special spark plug boot removal tool (usually supplied with the vehicle, attached to the hood prop rod) is required to remove the spark plug boots. Do NOT pull on the wires! They will be damaged.

  1. If available, using compressed air, blow any water or debris from the spark plug well to assure that no harmful contaminants are allowed to enter the combustion chamber when the spark plug is removed. If compressed air is not available, use a rag or a brush to clean the area.
  2.  


NOTE
Remove the spark plugs when the engine is cold, if possible, to prevent damage to the threads. If removal of the plugs is difficult, apply a few drops of penetrating oil or silicone spray to the area around the base of the plug, and allow it a few minutes to work.

  1. Using a spark plug socket that is equipped with a rubber insert to properly hold the plug, turn the spark plug counterclockwise to loosen and remove the spark plug from the bore.
  2.  


WARNING
Be sure not to use a flexible extension on the socket. Use of a flexible extension may allow a shear force to be applied to the plug. A shear force could break the plug off in the cylinder head, leading to costly and frustrating repairs.



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Fig. A swivel socket may be needed to reach difficult plugs



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Fig. The spark plug wires and coils are located beneath the trim cover



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Fig. A spark plug terminal removal tool is attached to the terminal on the 2.8L V6 Passat models



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Fig. Lift the tool off the plug terminal and install with the lift hook facing up to lift off the plug wire terminal



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Fig. The spark plug terminal shown removed from the spark plug

To install:

  1. Inspect the spark plug boot for tears or damage. If a damaged boot is found, the spark plug wire must be replaced.
  2.  
  3. On single electrode spark plugs, use a wire feeler gauge to check and adjust the spark plug gap. When using a gauge, the proper size should pass between the electrodes with a slight drag. The next larger size should not be able to pass while the next smaller size should pass freely.
  4.  


NOTE
Multiple electrode spark plugs should not be gapped. If the air gap exceeds the wear limits, the spark plugs must be replaced.

  1. Apply a light coating of an anti-seizing compound to the threads of the spark plug.
  2.  
  3. Carefully thread the plug into the bore by hand. If resistance is felt before the plug is almost completely threaded, back the plug out and begin threading again. In small, hard to reach areas, an old spark plug wire and boot or a section of rubber hose that can be slid over the spark plug could be used as a threading tool. The boot or hose will hold the plug while it is twisted and be supple enough to twist before it would allow the plug to cross-thread.
  4.  


WARNING
Do NOT use the spark plug socket and ratchet to start the threading of the spark plugs. Always carefully thread the plug by hand to prevent the possibility of cross-threading and damaging the cylinder head threads.

  1. Carefully tighten the spark plug and torque as follows:
  2.  


    1.8L Turbo (ABE) engines: 22 ft. lbs. (30 Nm)
     
    2.0L (9A) engines: 15 ft. lbs. (20 Nm)
     
    2.0L (ABA) engines: 22 ft. lbs. (30 Nm)
     
    VR6 engines: 18 ft. lbs. (25 Nm)
     
    V6 engines: 22 ft. lbs. (30 Nm)
     

  3. Apply a small amount of silicone dielectric compound to the end of the spark plug lead or inside the spark plug boot to prevent sticking, then install the boot to the spark plug and push until it clicks into place. The click may be felt or heard, then gently pull back on the boot to assure proper contact.
  4.  

1.8L (AWD) Engine

NOTE
This procedure requires the use of the following special tools, or their equivalents:



Spark plug wrench VAS 3122B
 
Seal puller T10018
 
Removal/Installation tool T10029
 
Puller T10095
 
Torque wrench V.A.G 1331/ (5 - 50 Nm)
 

  1. Make sure you have the radio code, if necessary.
  2.  
  3. Disconnect the negative battery cable.
  4.  
  5. Loosen the retaining screws, then remove the engine cover upward from the vehicle.

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    Fig. Loosen the screws (arrows), then remove the engine cover

  6.  
  7. Disconnect recirculating valve for turbocharger and secondary air inlet valve.
  8.  
  9. Remove bracket for both valves and for vacuum reservoir.
  10.  
  11. Remove the ignition coil screws (1).
  12.  
  13. Remove the ignition coils (2) together with the spark plug connectors.

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    Fig. Remove the ignition coil screws (1), then remove the ignition coils (2) together with the spark plug connectors

  14.  
  15. Remove spark plugs using Spark plug wrench VAS 3122B, or equivalent.
  16.  
  17. Inspect the spark plugs, as outlined in this section.

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    Fig. Spark plug applications-1.8L (AWD) Engines

  18.  

To install:

  1. Install spark plugs with Spark plug wrench VAS 3122B, or equivalent. Tighten to 22 ft. lbs. (30 Nm).
  2.  
  3. Install ignition coils together with spark plug connectors.
  4.  
  5. Connect the recirculating valve for turbocharger and secondary air inlet valve.
  6.  
  7. Install the bracket for both valves and for vacuum reservoir.
  8.  
  9. Check that the ignition wiring and spark plug connectors are seated securely
  10.  
  11. Position the engine cover in place then tighten the screws.
  12.  
  13. Connect the negative battery cable.
  14.  

 
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