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Diagnosis & Repair

WARNING: This page is about a different car, the 2002 Lexus ES 300. However, it is still accessible from the selected car via links, so may be relevant.
  1. Check vacuum hoses for leaks, blockage and proper routing. See VACUUM DIAGRAMS article. Also, check wiring and connectors for damage or poor connections. If problem exists, repair as necessary and perform TEST DRIVE CONFIRMATION . If problem does not exist, go to next step.
  2. Check spark and ignition system. See IGNITION CHECKS in BASIC DIAGNOSTIC PROCEDURES article. If problem exists, repair as necessary. If problem does not exist, go to next step.
  3. Access ECM behind glove box. Turn ignition on. Using DVOM, backprobe ECM connector and measure voltage between ground and fuel injector terminals at specified ECM connector. See IDENTIFYING ECM FUEL INJECTOR TERMINALS  table. If voltage is 9-14 volts at each terminal, go to step  6. If voltage is not 9-14 volts at each terminal, go to next step.
    IDENTIFYING ECM FUEL INJECTOR TERMINALS

    Fuel Injector No. Terminal No. Wire Color
    1 (1) 1 Blue
    2 (1) 2 Red
    3 (1) 3 Yellow
    4 (1) 4 White
    5 (1) 5 Red/Blue
    6 (1) 6 Green
    (1) Terminals are located in ECM harness connector E10. See Figure.
  4. Turn ignition off. Disconnect fuel injector harness connector at misfiring cylinder. Measure resistance between fuel injector terminals (component side). Resistance should be 13.4-14.2 ohms at 68°F (20°C). If resistance is as specified, go to next step. If resistance is not as specified, replace appropriate fuel injector.
  5. Check for open or short in wiring between ECM and fuel injector. See WIRING DIAGRAMS article. If problem exists, repair as necessary. If problem does not exist, repair open or short in fuel injector power source circuit. See WIRING DIAGRAMS article.
  6. Check fuel pressure. See FUEL SYSTEM in BASIC DIAGNOSTIC PROCEDURES. Fuel pressure should be 44-55 psi (3.1-3.9 kg/cm2 ) at idle, and should be 21 psi (1.5 kg/cm2 ) or more for 5 minutes after engine has stopped. If fuel pressure is not as specified, repair as necessary. If fuel pressure is as specified, go to next step.
  7. Check fuel injectors. See FUEL SYSTEM in SYSTEM & COMPONENT TESTING - ES300 & RX300 article. Fuel injector volume should be 3.7-4.5 Cu. In. (60-73 cc) every 15 seconds and difference in volume between each injector should be less than .8 Cu. In. (13 cc). Injectors should not leak more than one drop every 12 minutes. If problem exists, repair as necessary. If problem does not exist, go to next step.
  8. Check EGR system components. See EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING - ES300 & RX300 article. If problem exists, repair as necessary. If problem does not exist, go to next step.
  9. Check Mass Airflow (MAF) meter and Engine Coolant Temperature (ECT) sensor. See ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING - ES300 & RX300 article. If problem exists, replace appropriate sensor(s). If problem does not exist, go to next step.
  10. Check engine compression. See BASIC DIAGNOSTIC PROCEDURES article. Check valve clearance. See ON-VEHICLE ADJUSTMENTS article. Check valve timing. See appropriate article in ENGINES. Repair as necessary.
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