SFI SYSTEM Lack of Power or Hesitation

DESCRIPTION

The VALVEMATIC system is able to continuously change the valve lift amount and valve timing. For engines equipped with a VALVEMATIC system, when a part such as a rocker arm in the camshaft housing has mechanical problems, the valve lift amount does not change and problems occur, such as a lack of engine power or rough idling.

CAUTION / NOTICE / HINT

A lack of engine power occurs when the throttle valve is malfunctioning or when there is a clog in the intake or exhaust system. Therefore, during the inspection, confirm that there are no clogs in any parts.

Tech Tips


  • When the throttle valve is malfunctioning, even if the accelerator pedal is fully depressed when the engine is running, the throttle does not fully open.

  • When there is a clog in the intake system, even if the accelerator pedal is fully depressed, the MAP is not the same as the atmospheric pressure.

When performing this inspection on a vehicle equipped with the VALVEMATIC, perform the following procedures first in order to confirm that there are no VVT system malfunctions.


  1. Perform the VVT system Active Test and confirm that the VVT follows the VVT target.

  2. If the VVT system Active Test results are normal, perform the VALVEMATIC system Active Test.

Note

When the vehicle is not equipped with the VALVEMATIC, even if the VVT system inspection (the inspection that checks if idling becomes unstable when changing the VVT to the most advanced and retarded positions through the Active Test) is performed, it cannot be determined that the malfunction is in the VVT system.

PROCEDURE


  1. CHECK WHETHER DTC OUTPUT


    1. Connect the GTS to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the GTS on.

    4. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.


      Powertrain > Engine and ECT > Trouble Codes

    5. Read the DTCs.

      Result
      Result Proceed to
      DTC is not output A
      DTC is output B

    B

    GO TO DTC CHART Click here

    A

  2. PERFORM BASIC FUNCTION


    1. Check the air cleaner filter element sub-assembly.

      Tech Tips

      If the air cleaner filter element sub-assembly is dirty, clean or replace it.

    2. Check if there are any clogs in the intake or exhaust system.

    3. Check the ignition timing Click here.

    4. Check the fuel pressure Click here.

    5. Check the spark Click here.

    6. Measure the cylinder compression pressure Click here.

      Result
      Result Proceed to
      Everything normal A
      Repaired problem area but malfunction reoccurs
      Repaired problem area and malfunction does not reoccur B

      Tech Tips

      Perform "Inspection After Repair" after repairing or replacing the intake system, exhaust system, ignition system or engine assembly Click here.


    B

    END

    A

  3. READ VALUE USING GTS


    1. Connect the GTS to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the GTS on.

    4. Enter the following menus: Powertrain / Engine and ECT / Data List / All Data / Short FT #1, Long FT #1, AFS Voltage B1S1 and O2S B1S2.


      Powertrain > Engine and ECT > Data List
      Tester Display
      AFS Voltage B1S1
      O2S B1S2
      Short FT #1
      Long FT #1

    5. Read the value while driving the vehicle.

      Result
      Result Proceed to
      No abnormal values in Data List A
      Abnormal values in Data List B

    B

    CHECK FUEL SYSTEM

    A

  4. PERFORM ACTIVE TEST USING GTS (CONTROL THE VVT SYSTEM (BANK 1))


    1. Connect the GTS to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the GTS on.

    4. Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the VVT System (Bank1) / All Data / VVT Change Angle #1.


      Powertrain > Engine and ECT > Active Test
      Active Test Display
      Control the VVT System (Bank1)
      Data List Display
      VVT Change Angle #1

    5. Read the value.

      Result
      Result Proceed to
      The "VVT Change Angle #1" value changes A
      The "VVT Change Angle #1" value does not change B

    B

    CHECK VVT SYSTEM

    A

  5. PERFORM ACTIVE TEST USING GTS (ACTIVATE THE VALVEMATIC (ENG ON))


    1. Connect the GTS to the DLC3.

    2. Start the engine.

    3. Turn the GTS on.

    4. Enter the following menus: Powertrain / Engine and ECT / Active Test / Activate the VALVEMATIC (ENG ON) / All Data / MAP and VALVEMATIC Current Angle.


      Powertrain > Engine and ECT > Active Test
      Active Test Display
      Activate the VALVEMATIC(ENG ON)
      Data List Display
      MAF
      VALVEMATIC Current Angle

    5. Maintain an engine speed of 3000 rpm with the shift lever in P or N (neutral) and the vehicle stationary.

    6. Read the value.

      Standard
      GTS Operation Result
      High

      VALVEMATIC Current Angle: 260 deg(CA)

      MAP: 20 to 35 kPa(abs) (150 to 263 mmHg(abs))
      Low

      VALVEMATIC Current Angle: 106 deg(CA)

      MAP: 70 to 100 kPa(abs) (525 to 750 mmHg(abs))
      OK
      Change in MAP during the Active Test

      Tech Tips

      When the vehicle is driven while there is a malfunction in the VALVEMATIC system and the valve lift amount is fixed at the minimum, the vehicle speed cannot exceed 30 to 60 km/h (19 to 37 mph).

      Result
      Proceed to
      OK
      NG

    OK

    PERFORM SIMULATION TEST

    NG

    CHECK VALVEMATIC SYSTEM