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Home >> Lexus >> 2008 >> SC 430 >> Repair and Diagnosis >> Engine Performance >> Engine Control System >> SFI System >> DTC P050B: Cold Start Ignition Timing Performance >> Inspection Procedure
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Inspection Procedure

HINT:

DTC P050B may be set when the engine has the symptoms listed below. If necessary, check the trouble area listed below.

PROBLEM SYMPTOM CHART

Symptom Factor Trouble Area
Low idle speed when engine is cold Excessive engine friction
  • Engine oil deterioration
  • Drive belt tension
  • A/C compressor
  • Generator
  • P/S pump
Rough idle when engine is cold Abnormal combustion Fuel quality
  1. CHECK DTCS 

    Result: 

    Any other DTCs are not set. 

    NG:  GO TO DIAGNOSTIC TROUBLE CODE CHART 

    OK: Go to next step 

  2. READ SHORT-TERM AND LONG-TERM FUEL TRIMS 

    HINT:

    The total of the short-term fuel trim (Short FT) and long-term fuel trim (Long FT) is used to discover a problem in the induction system (between air cleaner and intake manifold).

    1. Allow the engine to idle.
    2. Enter the following menus: Powertrain / Engine and ECT / Data List.
    3. Read the value of Short FT #1 and Long FT #1 (bank 1).
    4. Read the value of Short FT #2 and Long FT #2 (bank 2).

    Result: 

    Total of Short FT and Long FT is between -20% and 20% 

    NG:  Go to step  4

    OK: Go to next step 

  3. CHECK THROTTLE BODY 
    1. Check for deposits around the throttle valve and throttle valve condition.

    Result: 

    No deposits around throttle valve and throttle valve moves smoothly. 

    NG:  Go to step  8

    OK:  Go to step  9

  4. CHECK VVT SYSTEM 
    1. Allow the engine to idle with the engine warmed up.
    2. Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the VVT System (Bank 1) or Control the VVT System (Bank 1).
    3. Turn on Control the VVT System (Bank 1) (or Control the VVT System (Bank 2)) to advance the valve timing.
    4. Check the engine condition.

    Result: 

    The engine stalls or idles roughly when Control the VVT System is ON. (VVT system is OK) 

    NG:  Go to step  10

    OK: Go to next step 

  5. CHECK PCV SYSTEM 
    1. Allow the engine to idle.
    2. Pinch the positive crankcase ventilation (PCV) hose.
    3. Check the engine rpm.

    Result: 

    The engine rpm rises when the PCV hose is pinched. 

    NG:  Go to step  11

    OK: Go to next step 

  6. CHECK AIR CLEANER FILTER 
    1. Visually check that the air cleaner filter is not excessively contaminated with dirt or oil.

    NG:  Go to step  12

    OK: Go to next step 

  7. CHECK AIR INDUCTION SYSTEM 
    1. Check the air induction system for vacuum leakage.

    NG:  Go to step  13

    OK:  Go to step  14

  8. REPAIR OR REPLACE THROTTLE BODY 

    NEXT:  Go to step  15

  9. REPLACE ECM 

    NEXT:  Go to step  15

  10. CHECK AND REPAIR VVT SYSTEM 

    NEXT:  Go to step  15

  11. REPAIR OR REPLACE PCV HOSE 

    NEXT:  Go to step  15

  12. REPLACE AIR CLEANER FILTER 

    NEXT:  Go to step  15

  13. REPAIR OR REPLACE AIR INDUCTION SYSTEM 

    NEXT:  Go to step  15

  14. REPLACE MASS AIR FLOW METER 

    NEXT:  Go to step  15

  15. CHECK DTCS 
  1. Check that the engine coolant temperature is -10 to 50°C (14 to 122°F).
  2. Clear the DTC.
  3. Enter the check mode using the Techstream.
  4. Allow the engine to idle for 1 minute.
  5. Check that no DTC is present.

NEXT: END 

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