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On-Vehicle Inspection

WARNING: This page is about a different car, the 2007 Lexus SC 430. However, it is still accessible from the selected car via links, so may be relevant.
  1. CHECK IGNITION TIMING 
    1. Warm up the engine and stop the engine.
      NOTE: A warmed up engine should have an engine coolant temperature of over 80°C (176°F), have an engine oil temperature of 60°C (140°F), and the engine rpm should be stabilized.
    2. Check the ignition timing.
      1. Connect the intelligent tester to the DLC3.
      2. Enter DATA LIST MODE on the intelligent tester.

        HINT:

        Refer to the intelligent tester operator's manual for further details.

      3. Start and idle the engine.

        Standard ignition timing: 8 to 12° BTDC @ idle (Shift lever on N) 

      4. Disconnect the intelligent tester from the DLC3.
        Fig 1: Connecting Intelligent Tester To DLC3
        G05288670Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  2. CHECK ENGINE IDLE SPEED 
    1. Warm up the engine.
      NOTE: A warmed up engine should have an engine coolant temperature of over 80°C (176°F) and an engine oil temperature of 60°C (140°F), and the engine rpm should be stabilized.
    2. Check the idle speed.
      1. Connect the intelligent tester to the DLC3.
      2. Enter DATA LIST MODE on the intelligent tester.

        Standard idle speed: 700 to 800 rpm 

        NOTE:
        • When checking the idle speed, the transmission should be in neutral.
        • Check the idle speed with the cooling fan off.
        • Switch off all accessories and A/C before connecting the intelligent tester.

        HINT:

        Refer to the intelligent tester operator's manual for further details.

        If the idle speed is not as specified, check the air intake system.

  3. CHECK COMPRESSION 
    1. Remove the V-bank cover.
    2. Remove the air cleaner inlet and intake air pipe.
    3. Disconnect the throttle control motor connector.
    4. Remove the oil level gauge guide.
    5. Remove the 8 ignition coils.
    6. Remove the 8 spark plugs.
    7. Disconnect the 8 injector connectors.
    8. Check the cylinder compression pressure.
      1. Insert a compression gauge into the spark plug hole.
      2. Fully open the throttle.
      3. While cranking the engine, measure the compression pressure.

        Standard compression pressure: 1,226 kPa (12.5 kgf/cm 2  , 178 psi) or more 

        Minimum pressure: 981 kPa (10.0 kgf/cm 2  , 142 psi) 

        Difference between each cylinder: 98 kPa (1.0 kgf/cm 2  , 14 psi) 

        Fig 2: Inserting Compression Gauge Into Spark Plug Hole
        G05288671Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
        NOTE:
        • Always use a fully charged battery to obtain an engine speed of 250 rpm or more.
        • Check the other cylinder's compression pressure in the same way.
        • This measurement must be done as quickly as possible.

        If the cylinder compression is low, pour a small amount of engine oil into the cylinder through the spark plug hole and inspect again.

        HINT:

        • If adding oil increases the compression, the piston rings and/or cylinder bore may be worn or damaged.
        • If pressure stays low, a valve may be stuck or seated improperly, or there may be leakage in the gasket.
    9. Connect the 8 injector connectors.
    10. Install the 8 spark plugs.
    11. Install the 8 ignition coils.
    12. Install the oil level gauge guide.
    13. Connect the throttle control motor connector.
    14. Install the air cleaner inlet and intake air pipe.
    15. Install the V-bank cover.
  4. CHECK CO/HC 
    1. Start the engine.
    2. Rev the engine at 2,500 rpm for approximately 180 seconds.
    3. Insert a CO/HC meter testing probe at least 40 cm (1.3 ft.) into the tailpipe during idling.
    4. Check CO/HC concentration at idle and/or 2,500 rpm.

      HINT:

      • Complete the measurement within 3 minutes.
      • Check regulations in your area when performing 2 mode CO/HC concentration testing (check at both idle speed and at 2,500 rpm).
        Fig 3: Checking CO/HC
        G05288672Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    5. If the CO/HC concentration does not comply with regulations, perform troubleshooting in the order given below.
      1. Check the heated oxygen sensor operation (see DESCRIPTION ).
      2. See the table below for possible causes, and then inspect and repair.
        POSSIBLE CAUSES SYMPTOM CHART

        CO HC Symptom Causes
        Normal High Rough idle
        1. Faulty ignitions:
          • Incorrect timing
          • Fouled, shorted or improperly gapped plugs.
        2. Incorrect valve clearance
        3. Leaky intake and exhaust valves
        4. Leaky cylinder
        Low High Rough idle (fluctuating HC reading)
        1. Vacuum leaks:
          • PCV hose
          • Intake manifold
          • Throttle body
        2. Lean mixture causing misfire
        High High Rough idle (black smoke from exhaust)
        1. Restricted air filter
        2. Faulty SFI system:
          • Faulty pressure regulator
          • Defective ECT sensor
          • Faulty ECM
          • Faulty injector
          • Faulty throttle position sensor
          • MAF sensor
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