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    Volkswagen Cars 2000-05

    Spark Plug Wires

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    Removal & Installation





    Click image to see an enlarged view

    Fig. Number the plug wires before removal

    If the wires are being replaced, remove one wire and match the length with the new wire. Install the new wire before removing the next old one. If the wires are to be reinstalled, remove them one at a time from the distributor cap before disconnecting them from the spark plugs. As each wire is removed from the distributor cap, mark the cylinder number on the boot and on the cap.

    On some vehicles with the Motronic system, an ignition reference sensor is attached to the No. 4 plug wire. The ECU uses the input from this sensor when calculating the timing retard required to stop the engine knock.



    Click image to see an enlarged view

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

    A set of spark plugs usually requires replacement after about 20,000-30,000 miles (32,000-48,000 km), 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.

    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 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. 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.

    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. Using a wire feeler gauge, 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.  
    5. Apply a light coating of anti-seize compound to the threads of the spark plug.
    6.  
    7. 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 could be used as a threading tool. The boot will hold the plug while you twist the end of the wire and the wire is supple enough to twist before it would allow the plug to crossthread.
    8.  


    WARNING
    Do not use the spark plug socket to thread the plugs. Always carefully thread the plug by hand or using an old plug wire to prevent the possibility of crossthreading and damaging the cylinder head bore.

    1. Carefully tighten the spark plug. If the plug you are installing is equipped with a crush washer, seat the plug, then tighten about 1 / 4 turn to crush the washer. If you are installing a tapered seat plug, tighten the plug to specifications provided by the vehicle or plug manufacturer.
    2.  
    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.  



    Click image to see an enlarged view

    Fig. Number the plug wires before removal

    If the wires are being replaced, remove one wire and match the length with the new wire. Install the new wire before removing the next old one. If the wires are to be reinstalled, remove them one at a time from the distributor cap before disconnecting them from the spark plugs. As each wire is removed from the distributor cap, mark the cylinder number on the boot and on the cap.

    On some vehicles with the Motronic system, an ignition reference sensor is attached to the No. 4 plug wire. The ECU uses the input from this sensor when calculating the timing retard required to stop the engine knock.

    Testing



    At every tune-up/inspection, visually check the spark plug cables for burns cuts, or breaks in the insulation. Check the boots and the nipples on the distributor cap and/or coil. Replace any damaged wiring; cracked or shorted spark plug wires can short to ground, and cause a 'miss' when the engine is running.

    Every 50,000 miles (80,000 Km) or 60 months, the resistance of the wires should be checked with an ohmmeter. Wires with excessive resistance will cause misfiring, and may make the engine difficult to start in damp weather.

    To check resistance, remove one wire from the engine, and measure the resistance from the spark plug connector to the distributor/coil pack connector. The resistance should be approximately 4600-7400 ohms. If the wire resistance is higher than 7400 ohms, the wire should be replaced. Coil wires (the wire that runs from the coil to the distributor) should have a resistance of 1200-2700 ohms.

    These engines use a special type of spark plug wire connector that is unique; if the spark plug wires are in need of replacement, make sure to replace them with OEM-equivalent wires to ensure proper ignition system operation.

    At every tune-up/inspection, visually check the spark plug cables for burns cuts, or breaks in the insulation. Check the boots and the nipples on the distributor cap and/or coil. Replace any damaged wiring; cracked or shorted spark plug wires can short to ground, and cause a "miss" when the engine is running.

    Every 50,000 miles (80,000 Km) or 60 months, the resistance of the wires should be checked with an ohmmeter. Wires with excessive resistance will cause misfiring, and may make the engine difficult to start in damp weather.

    To check resistance, remove one wire from the engine, and measure the resistance from the spark plug connector to the distributor/coil pack connector. The resistance should be approximately 4600-7400 ohms. If the wire resistance is higher than 7400 ohms, the wire should be replaced. Coil wires (the wire that runs from the coil to the distributor) should have a resistance of 1200-2700 ohms.

    Volkswagen uses a special type of spark plug wire connector that is unique; if the spark plug wires are in need of replacement, make sure to replace them with OEM-equivalent wires to ensure proper ignition system operation.

     
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