Section 2 (Engine Mechanical (3UZ-FE)): Engine: Inspection

WARNING: This page is about a different car, the 2007 Lexus GS 430. However, it is still accessible from the selected car via links, so may be relevant.

INSPECT IGNITION TIMING
1. Warm up the engine and stop the engine.
2. Check the ignition timing.
  1. Connect the intelligent tester to the DLC3.
  2. Enter DATA LIST MODE on the intelligent tester.
    HINT:
    
    Please refer to the intelligent tester operator's manual for further details.
  3. Start and idle the engine.
    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
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
INSPECT ENGINE IDLE SPEED
1. Warm up the engine.
2. Check the idle speed.
  1. Connect the intelligent tester to the DLC3.
  2. Enter DATA LIST MODE on the intelligent tester.
    Idle speed:
    
    700 to 800 rpm
    NOTE:
    When checking the idle speed, make sure the shift lever is on N.
    
    Check the idle speed with the cooling fan off.
    
    Switch off all accessories and the A/C before connecting the intelligent tester.
Fig 2: Connecting Intelligent Tester To DLC3
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
INSPECT 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.
    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 3: Checking Cylinder Compression Pressure
  Courtesy 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.

INSPECT CO/HC

Start the engine.
Rev the engine at 2,500 rpm for approximately 180 seconds.
Insert CO/HC meter testing probe at least 40 cm (1.3 ft) into the tailpipe during idling.
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 (engine check at both idle speed and at 2,500 rpm).
If the CO/HC concentration does not comply with regulations, perform troubleshooting in the order given below.
1. Check heated oxygen sensor operation (see DTC P0136 OXYGEN SENSOR CIRCUIT MALFUNCTION (BANK 1 SENSOR 2); DTC P0138 OXYGEN SENSOR CIRCUIT HIGH VOLTAGE (BANK 1 SENSOR 2); DTC P0139 OXYGEN SENSOR CIRCUIT SLOW RESPONSE (BANK 1 SENSOR 2); DTC P0156 OXYGEN SENSOR CIRCUIT MALFUNCTION (BANK 2 SENSOR 2); DTC P0158 OXYGEN SENSOR CIRCUIT HIGH VOLTAGE (BANK 2 SENSOR 2); DTC P0159 OXYGEN SENSOR CIRCUIT SLOW RESPONSE (BANK 2 SENSOR 2) ).
2. See the table below for possible causes, and then inspect and repair.

Fig 4: Inserting CO/HC Meter Testing Probe Into Tailpipe During Idling

SYMPTOM CHART

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