Yaris 2007

Spark Plugs

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Inspection



Specific to:

Toyota Yaris 2007-2010

  1. Inspect the terminal post for damage
  2.  
  3. Inspect for a bent or broken terminal post
  4.  
  5. Test for a loose terminal post by twisting and pulling the post. The terminal post should NOT move.
  6.  
  7. Inspect the insulator for flashover or carbon tracking, soot. This is caused by the electrical charge traveling across the insulator between the terminal post and ground.
  8.  
  9. Inspect for the following conditions:
  10.  
  11. Inspect the spark plug boot for damage
  12.  
  13. Inspect the spark plug recess area of the cylinder head for moisture, such as oil, coolant, or water. A spark plug boot that is saturated causes arcing to ground.
  14.  
  15. Inspect the insulator for cracks. All or part of the electrical charge may arc through the crack instead of the electrodes
  16.  
  17. Inspect for evidence of improper arcing
  18.  
  19. Measure the gap between the center electrode and the side electrode terminals. An excessively wide electrode gap can prevent correct spark plug operation.
  20.  
  21. Inspect for the correct spark plug torque. Insufficient torque can prevent correct spark plug operation. An over-torqued spark plug causes the insulator to crack.
  22.  
  23. Inspect for signs of tracking that occurred near the insulator tip instead of the center electrode
  24.  
  25. Inspect for a broken or worn side electrode
  26.  
  27. Inspect for a broken, worn, or loose center electrode by shaking the spark plug.
  28.  
  29. A rattling sound indicates internal damage
  30.  
  31. A loose center electrode reduces the spark intensity.
  32.  
  33. Inspect for bridged electrodes. Deposits on the electrodes reduce or eliminates the gap.
  34.  
  35. Inspect for worn or missing platinum pads on the electrodes if equipped
  36.  
  37. Inspect for excess fouling
  38.  
  39. Inspect the spark plug recess area of the cylinder head for debris. Dirty or damaged threads can cause the spark plug not to seat correctly during installation
  40.  
  41. Normal operation--Brown to grayish-tan with small amounts of white powdery deposits are normal combustion by-products from fuels with additives.
  42.  
  43. Carbon fouled--Dry, fluffy, black carbon, or soot caused by the following conditions:

    Rich fuel mixtures
     
    Leaking fuel injectors
     
    Excessive fuel pressure
     
    Restricted air filter element
     
    Incorrect combustion
     
    Reduced ignition system voltage output
     
    Weak coils
     
    Worn ignition wires
     
    Incorrect spark plug gap
     

  44.  
  45. Excessive idling or slow speeds under light loads can keep spark plug temperatures so low that normal combustion deposits may not burn off.
  46.  
  47. Deposit fouling: Oil, coolant, or additives that include substances such as silicone, very white coating, reduces the spark intensity. Most powdery deposits will not affect spark intensity unless they form into a glazing over the electrode.
  48.  

Removal & Installation



Specific to:

Toyota Yaris 2007-2010

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the 4 nuts and the engine cover.
  4.  
  5. Disconnect the 4 ignition coil connectors.
  6.  
  7. Remove the 4 bolts and 4 ignition coils.
  8.  
  9. Using a 14 mm spark plug wrench, remove the 4 spark plugs.
  10.  
  11. To install, reverse the removal procedure.
  12.  
  13. Tighten the spark plugs to 13 ft. lbs. (18 Nm).

    Click image to see an enlarged view

    Fig. Removing spark plugs and components

  14.  

 
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