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Home >> Lexus >> 2011 >> IS 350 Base, AWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System (Diagnostic Codes (P0171-P060A)) >> SFI System >> DTC P050A: Cold Start Idle Air Control System Performance >> Procedure
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DTC P050A: Cold Start Idle Air Control System Performance: Procedure

  1. CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P050A) 
    1. Connect the Techstream to the DLC3.
    2. Turn the engine switch on (IG).
    3. Turn the Techstream on.
    4. Enter the following menus: Powertrain / Engine / Trouble Codes.
    5. Read the DTCs.

      Result

      Display (DTC Output) Proceed to
      P050A A
      P050A and other DTCs B

      HINT: 

      If any DTCs other than P050A are output, troubleshoot those DTCs first.

    B → See step   21 

    A: Go to next step 

  2. READ VALUE USING TECHSTREAM (FUEL TRIM) 

    HINT: 

    Calculate the total fuel trim values to check the characteristic deviation of the mass air flow meter.

    1. Connect the Techstream to the DLC3.
    2. Start the engine.
    3. Turn the Techstream on.
    4. Enter the following menus: Powertrain / Engine / Data List / All Data / Short FT #1 and Long FT #1, or Short FT #2 and Long FT #2.
    5. Read the values displayed on the Techstream while the engine is idling.
    6. Add together the Short FT #1 and Long FT #1, or Short FT #2 and Long FT #2 values to obtain the total fuel trim.

      Result

      Total of Short FT #1 and Long FT #1, or Short FT #2 and Long FT #2 values is between -20% and 20%.

    NG → See step   5 

    OK: Go to next step 

  3. INSPECT THROTTLE BODY ASSEMBLY 
    1. Check for deposits around the throttle valve and check the throttle valve condition.

      OK

      No deposits around throttle valve and throttle valve moves smoothly.

      Result

      Result Proceed to
      NG A
      OK B

    B → See step   14 

    A: Go to next step 

  4. REPAIR OR REPLACE THROTTLE BODY ASSEMBLY 
    1. Repair or replace the throttle body assembly. Refer to REMOVAL .

    NEXT → See step   14 

  5. CHECK PCV SYSTEM 
    1. Check the PCV hose connections. Refer to ON-VEHICLE INSPECTION - Step 1 .

      OK

      PCV hose is connected correctly and is not damaged.

    NG → See step   10 

    OK: Go to next step 

  6. CHECK AIR INDUCTION SYSTEM 
    1. Check the air induction system for vacuum leaks.

      OK

      No leaks in air induction system.

    NG → See step   11 

    OK: Go to next step 

  7. CHECK AIR CLEANER FILTER ELEMENT SUB-ASSEMBLY 
    1. Visually check that the air cleaner filter element is not excessively contaminated with dirt or oil.

      OK

      Air cleaner filter element is not excessively contaminated with dirt or oil.

    NG → See step   12 

    OK: Go to next step 

  8. PERFORM ACTIVE TEST USING TECHSTREAM (CONTROL THE VVT LINEAR) 
    1. Connect the Techstream to the DLC3.
    2. Start the engine and turn the Techstream on.
    3. Warm up the engine.
    4. Enter the following menus: Powertrain / Engine / Active Test / Control the VVT Linear (Bank 1) or Control the VVT Linear (Bank 2).
    5. Check the engine speed while operating the camshaft timing oil control valve (OCV) using the Techstream.

      OK

      Techstream Operation Specified Condition
      0% Normal engine speed
      100% Engine idles roughly or stalls

    NG → See step   13 

    OK: Go to next step 

  9. READ VALUE USING TECHSTREAM (MAF) 
    1. Connect the Techstream to the DLC3.
    2. Start the engine.
    3. Turn the Techstream on.
    4. Enter the following menus: Powertrain / Engine / Data List / All Data / MAF and Coolant Temp.
    5. Allow the engine to idle until Coolant Temp reaches 75°C (167°F) or higher.
    6. Read MAF with the engine speed at 3000 rpm.

      Standard

      Between 13.0 gm/sec and 14.0 gm/sec (shift lever: N; A/C: Off).

    OK → See step   14 

    NG → See step   15 

  10. REPAIR OR REPLACE PCV HOSE 
    1. Repair or replace PCV hose.

    NEXT → See step   14 

  11. REPAIR OR REPLACE AIR INDUCTION SYSTEM 
    1. Repair or replace the air induction system.

    NEXT → See step   14 

  12. REPLACE AIR CLEANER FILTER ELEMENT SUB-ASSEMBLY 
    1. Replace the air cleaner filter element sub-assembly.

    NEXT → See step   14 

  13. CHECK AND REPAIR VVT SYSTEM 
    1. Check and repair the VVT system.

    NEXT: Go to next step 

  14. CHECK WHETHER DTC OUTPUT RECURS (P050A) 
    NOTE:

    In this operation, the engine must be cold (approximately the same as the engine coolant temperature recorded in the freeze frame data).

    1. Connect the Techstream to the DLC3.
    2. Turn the engine switch on (IG).
    3. Turn the Techstream on.
    4. Clear the DTCs. Refer to DTC CHECK / CLEAR .
    5. Turn the engine switch off and wait for 30 seconds.
    6. Turn the engine switch on (IG) and turn the Techstream on.
    7. Enter the following menus: Powertrain / Engine / Data List / Coolant Temp.
    8. Check that the engine coolant temperature is between -10°C and 60°C (14 and 140°F).
    9. Start the engine and warm it up.
    10. Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.
    11. Enter the following menus: Powertrain / Engine / Utility / All Readiness.
    12. Input the DTC: P050A.
    13. Check the DTC judgment result.

      Result

      Result Proceed to
      NORMAL (DTC is not output) A
      ABNORMAL (DTC P050A is output) B

    B → See step   15 

    A → See step   22 

  15. CHECK HARNESS AND CONNECTOR 
    1. Check the connection and terminal contact pressure of connectors and wire harnesses between the mass air flow meter and ECM. Refer to ELECTRONIC CIRCUIT INSPECTION PROCEDURE .

      HINT: 

      Repair any problems.

    NEXT: Go to next step 

  16. CHECK WHETHER DTC OUTPUT RECURS 
    NOTE:

    In this operation, the engine must be cold (approximately the same as the engine coolant temperature recorded in the freeze frame data).

    1. Connect the Techstream to the DLC3.
    2. Turn the engine switch on (IG).
    3. Turn the Techstream on.
    4. Clear the DTCs. Refer to DTC CHECK / CLEAR .
    5. Turn the engine switch off and wait for 30 seconds.
    6. Turn the engine switch on (IG) and turn the Techstream on.
    7. Enter the following menus: Powertrain / Engine / Data List / Coolant Temp.
    8. Check that the engine coolant temperature is between -10°C and 60°C (14 and 140°F).
    9. Start the engine and warm it up.
    10. Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.
    11. Enter the following menus: Powertrain / Engine / Utility / All Readiness.
    12. Input the DTC: P050A.
    13. Check the DTC judgment result.

      Result

      Result Proceed to
      ABNORMAL (DTC P050A is output) A
      NORMAL (DTC is not output) B

    B → END 

    A: Go to next step 

  17. CHECK HARNESS AND CONNECTOR (MAS AIR FLOW METER - ECM) 
    1. Disconnect the E29 MAF meter connector.
    2. Disconnect the E5 ECM connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance (Check for open)

      Tester Connection Specified Condition
      VG (E29-5) - VG (E5-27) Below 1 Ω
      E2G (E29-4) - E2G (E5-26) Below 1 Ω

      Standard Resistance (Check for short)

      Tester Connection Specified Condition
      VG (E29-5) or VG (E5-27) - Body ground 10 kΩ or higher
    4. Reconnect the ECM connector.
    5. Reconnect the MAF meter connector.

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to next step 

  18. REPLACE MASS AIR FLOW METER 
    1. Replace the mass air flow meter. Refer to REMOVAL .

      HINT: 

      If the result of the inspection performed in step 9 indicated no problem, proceed to the next step without replacing the mass air flow meter assembly.

    NEXT: Go to next step 

  19. CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIRED 
    NOTE:

    In this operation, the engine must be cold (approximately the same as the engine coolant temperature recorded in the freeze frame data).

    1. Connect the Techstream to the DLC3.
    2. Turn the engine switch on (IG).
    3. Turn the Techstream on.
    4. Clear the DTCs. Refer to DTC CHECK / CLEAR .
    5. Turn the engine switch off and wait for 30 seconds.
    6. Turn the engine switch on (IG) and turn the Techstream on.
    7. Enter the following menus: Powertrain / Engine / Data List / Coolant Temp.
    8. Check that the engine coolant temperature is between -10°C and 60°C (14 and 140°F).
    9. Start the engine and warm it up.
    10. Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.
    11. Enter the following menus: Powertrain / Engine / Utility / All Readiness.
    12. Input the DTC: P050A.
    13. Check the DTC judgment result.

      Result

      Result Proceed to
      NORMAL (DTC is not output) A
      ABNORMAL (DTC P050A is output) B

    B → See step   20 

    A → END 

  20. REPLACE ECM. Refer to  REMOVAL 
  21. GO TO DTC CHART. Refer to  DIAGNOSTIC TROUBLE CODE CHART 
  22. CHECK FOR INTERMITTENT PROBLEMS. Refer to  CHECK FOR INTERMITTENT PROBLEMS 
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