SRX 2004-2005

Spark Plugs

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Inspection & Gapping



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. 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. 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. 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

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. 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. 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. 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

Removal & Installation



3.6L Engine
  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Turn the ignition OFF .
  4.  
  5. Remove the ignition coil.
    NOTE
    Clean the spark plug recess area before removing the spark plug. Failure to do so could result in engine damage because of dirt or foreign material entering the cylinder head, or by the contamination of the cylinder head threads. The contaminated threads may prevent the proper seating of the new plug. Use a thread chaser to clean the threads of any contamination.

  6.  
  7. Use compressed air in order to remove debris from the spark plug cavity.
    NOTE
    Allow the engine to cool before removing the spark plugs. Attempting to remove the spark plugs from a hot engine may cause the plug threads to seize, causing damage to cylinder head threads.

  8.  
  9. Remove the spark plug.

    Click image to see an enlarged view

    Fig. Spark plug removal-3.6L engine

  10.  

To install:


NOTE
Use only the spark plugs specified for use in the vehicle. Do not install spark plugs that are either hotter or colder than those specified for the vehicle. Installing spark plugs of another type can severely damage the engine.


NOTE
Check the gap of all new and reconditioned spark plugs before installation. The pre-set gaps may have changed during handling. Use a round feeler gage to ensure an accurate check. Installing the spark plugs with the wrong gap can cause poor engine performance and may even damage the engine. Ensure that the spark plug gap is equivalent to the spark plug gap specification.


NOTE
Be sure that the spark plug threads smoothly into the cylinder head and the spark plug is fully seated. Use a thread chaser, if necessary, to clean threads in the cylinder head. Cross-threading or failing to fully seat the spark plug can cause overheating of the plug, exhaust blow-by, or thread damage.

  1. Install the spark plug and tighten to 15 ft. lbs. (20 Nm).
  2.  
  3. Install the ignition coil.
  4.  

  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Turn the ignition OFF .
  4.  
  5. Remove the ignition coil.
    NOTE
    Clean the spark plug recess area before removing the spark plug. Failure to do so could result in engine damage because of dirt or foreign material entering the cylinder head, or by the contamination of the cylinder head threads. The contaminated threads may prevent the proper seating of the new plug. Use a thread chaser to clean the threads of any contamination.

  6.  
  7. Use compressed air in order to remove debris from the spark plug cavity.
    NOTE
    Allow the engine to cool before removing the spark plugs. Attempting to remove the spark plugs from a hot engine may cause the plug threads to seize, causing damage to cylinder head threads.

  8.  
  9. Remove the spark plug.

    Click image to see an enlarged view

    Fig. Spark plug removal-3.6L engine

  10.  

To install:


NOTE
Use only the spark plugs specified for use in the vehicle. Do not install spark plugs that are either hotter or colder than those specified for the vehicle. Installing spark plugs of another type can severely damage the engine.


NOTE
Check the gap of all new and reconditioned spark plugs before installation. The pre-set gaps may have changed during handling. Use a round feeler gage to ensure an accurate check. Installing the spark plugs with the wrong gap can cause poor engine performance and may even damage the engine. Ensure that the spark plug gap is equivalent to the spark plug gap specification.


NOTE
Be sure that the spark plug threads smoothly into the cylinder head and the spark plug is fully seated. Use a thread chaser, if necessary, to clean threads in the cylinder head. Cross-threading or failing to fully seat the spark plug can cause overheating of the plug, exhaust blow-by, or thread damage.

  1. Install the spark plug and tighten to 15 ft. lbs. (20 Nm).
  2.  
  3. Install the ignition coil.
  4.  

4.6L Engines
  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Remove the ignition control modules.
    CAUTION
    Wear safety glasses when using compressed air, as flying dirt particles may cause eye injury.


    NOTE
    Clean the spark plug recess area before removing the spark plug. Failure to do so could result in engine damage because of dirt or foreign material entering the cylinder head, or by the contamination of the cylinder head threads. The contaminated threads may prevent the proper seating of the new plug. Use a thread chaser to clean the threads of any contamination.

  4.  
  5. Clean the spark plug recess area with low pressure air.
    NOTE
    Allow the engine to cool before removing the spark plugs. Attempting to remove the spark plugs from a hot engine may cause the plug threads to seize, causing damage to cylinder head threads.

  6.  
  7. Remove the spark plugs from the cylinder heads.
  8.  
  9. Inspect the spark plugs.

    Click image to see an enlarged view

    Fig. Spark plug removal-4.6L

  10.  

To install:


NOTE
Use only the spark plugs specified for use in the vehicle. Do not install spark plugs that are either hotter or colder than those specified for the vehicle. Installing spark plugs of another type can severely damage the engine.


NOTE
Check the gap of all new and reconditioned spark plugs before installation. The pre-set gaps may have changed during handling. Use a round feeler gage to ensure an accurate check. Installing the spark plugs with the wrong gap can cause poor engine performance and may even damage the engine.

  1. Measure the spark plug gap on the spark plugs to be installed, correct as necessary.
    NOTE
    Be sure that the spark plug threads smoothly into the cylinder head and the spark plug is fully seated.

  2.  
  3. Use a thread chaser, if necessary, to clean threads in the cylinder head. Cross-threading or failing to fully seat the spark plug can cause overheating of the plug, exhaust blow-by, or thread damage.
  4.  
  5. Install the spark plugs to the cylinder heads tighten to 15 ft. lbs. (20 Nm).
  6.  
  7. Install the ignition control modules.
  8.  

  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Remove the ignition control modules.
    CAUTION
    Wear safety glasses when using compressed air, as flying dirt particles may cause eye injury.


    NOTE
    Clean the spark plug recess area before removing the spark plug. Failure to do so could result in engine damage because of dirt or foreign material entering the cylinder head, or by the contamination of the cylinder head threads. The contaminated threads may prevent the proper seating of the new plug. Use a thread chaser to clean the threads of any contamination.

  4.  
  5. Clean the spark plug recess area with low pressure air.
    NOTE
    Allow the engine to cool before removing the spark plugs. Attempting to remove the spark plugs from a hot engine may cause the plug threads to seize, causing damage to cylinder head threads.

  6.  
  7. Remove the spark plugs from the cylinder heads.
  8.  
  9. Inspect the spark plugs.

    Click image to see an enlarged view

    Fig. Spark plug removal-4.6L

  10.  

To install:


NOTE
Use only the spark plugs specified for use in the vehicle. Do not install spark plugs that are either hotter or colder than those specified for the vehicle. Installing spark plugs of another type can severely damage the engine.


NOTE
Check the gap of all new and reconditioned spark plugs before installation. The pre-set gaps may have changed during handling. Use a round feeler gage to ensure an accurate check. Installing the spark plugs with the wrong gap can cause poor engine performance and may even damage the engine.

  1. Measure the spark plug gap on the spark plugs to be installed, correct as necessary.
    NOTE
    Be sure that the spark plug threads smoothly into the cylinder head and the spark plug is fully seated.

  2.  
  3. Use a thread chaser, if necessary, to clean threads in the cylinder head. Cross-threading or failing to fully seat the spark plug can cause overheating of the plug, exhaust blow-by, or thread damage.
  4.  
  5. Install the spark plugs to the cylinder heads and tighten to 15 ft. lbs. (20 Nm).
  6.  
  7. Install the ignition control modules.
  8.  

 
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