ENGINE RUNS ROUGH/ROLLING IDLE [SKYACTIV-G]
ENGINE RUNS ROUGH/ROLLING IDLE [SKYACTIV-G]
SM2334609
id0103s4889500
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Troubleshooting item |
Engine runs rough/rolling idle |
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Description
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• Idle speed lower than the specification.
• Idling speed unstable, increases/decreases.
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Possible cause
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• Engine overheating
• PCM DTC is stored
• Erratic signal to PCM
• Improper load signal input
• Improper operation of A/C system
• Improper operation of drive-by-wire control system
• Incorrect fuel injection timing
• Fuel injector malfunction
• Purge solenoid valve malfunction
• Poor fuel quality
• Air leakage from intake-air system
• Intake-air system restriction
• Electrical connector disconnected
• Fuel leakage
• Vacuum leakage
• Improper engine oil viscosity
• Erratic signal from CKP sensor
• Erratic or no signal from CMP sensor
• Inadequate fuel pressure (high or low pressure side)
• Improper operation of electric variable valve timing control system (PCM DTC is stored.)
• Improper operation of hydraulic variable valve timing control system
• Low engine compression
• Improper intake valve timing
• Improper exhaust valve timing
• Spark plug malfunction
• Ignition coil malfunction
• Exhaust system and/or TWC restriction
• PCV valve malfunction
• Injector driver (built-into PCM) malfunction
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Possible cause
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Caution
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• Verify the malfunction symptom according to not only the PID value but also the symptom troubleshooting.
Related PIDs
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PIDs |
Reference |
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A/C_REQ
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APP1
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APP2
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ECT
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ECT_VOLT
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ECT2
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ECT2_VOLT
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FUEL_PRES
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LOAD_CALC
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LONG_FUEL_TRIM
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MAF
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MAP
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MAP_VOLT
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A/F_SEN_CUR
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HO2S_OUT_VOLT
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ENG_RPM
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SHRT_FUEL_TRIM
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TP_RELAT
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VSS
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Diagnostic Procedure
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Step |
Inspection |
Results |
Action |
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1
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VERIFY IF MALFUNCTION INCLUDES HARD ENGINE STARTING
• Verify the vehicle engine condition.
• Can idling be maintained?
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Yes
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Go to the next step.
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No
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Perform the symptom troubleshooting “ENGINE STALLS-AFTER START/AT IDLE”.
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2
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VERIFY IF MALFUNCTION CAUSE IS OVERHEATING
• Access the ECT PID using the M-MDS. (See PID/DATA MONITOR INSPECTION.)
• Is the ECT PID value less than 116 °C {241 °F} during driving?
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Yes
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Go to the next step.
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No
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The cause of this concern could be from the cooling system overheating.
• Perform the symptom troubleshooting “COOLING SYSTEM CONCERNS-OVERHEATING”. (See COOLING SYSTEM CONCERNS-OVERHEATING [SKYACTIV-G (US)].)
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3
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VERIFY PCM DTC
• Perform the DTC inspection for the PCM. (See DTC INSPECTION.)
• Are any DTCs displayed?
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Yes
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Repair the malfunctioning location according to the applicable DTC troubleshooting.
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No
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Go to the next step.
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4
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VERIFY CURRENT INPUT SIGNAL STATUS
• Access the following PIDs using the M-MDS: (See PID/DATA MONITOR INSPECTION.)
• Do the PIDs indicate the correct values under the malfunction condition? (See PID/DATA MONITOR TABLE [PCM (SKYACTIV-G (US))].)
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Yes
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Go to the next step.
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No
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APP1, APP2 PIDs are not as specified:
• Inspect the APP sensor No.1 and No.2. (See ACCELERATOR PEDAL POSITION (APP) SENSOR INSPECTION [SKYACTIV-G (WITH CYLINDER DEACTIVATION (US))].) (See ACCELERATOR PEDAL POSITION (APP) SENSOR INSPECTION [SKYACTIV-G (WITHOUT CYLINDER DEACTIVATION (US))].)
ECT, ECT_VOLT, ECT2, ECT2_VOLT PIDs are not as specified:
• Inspect the ECT sensor No.1 and No.2. (See ENGINE COOLANT TEMPERATURE (ECT) SENSOR INSPECTION [SKYACTIV-G (WITH CYLINDER DEACTIVATION (US))].) (See ENGINE COOLANT TEMPERATURE (ECT) SENSOR INSPECTION [SKYACTIV-G (WITHOUT CYLINDER DEACTIVATION (US))].)
MAF PID is not as specified:
• Inspect the MAF sensor. (See MASS AIR FLOW (MAF) SENSOR INSPECTION [SKYACTIV-G (WITH CYLINDER DEACTIVATION (US))].) (See MASS AIR FLOW (MAF) SENSOR INSPECTION [SKYACTIV-G (WITHOUT CYLINDER DEACTIVATION (US))].)
MAP, MAP_VOLT PIDs are not as specified:
• Inspect the MAP sensor. (See MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR INSPECTION [SKYACTIV-G (WITH CYLINDER DEACTIVATION (US))].) (See MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR INSPECTION [SKYACTIV-G (WITHOUT CYLINDER DEACTIVATION (US))].)
A/F_SEN_CUR, SHRT_FUEL_TRIM, LONG_FUEL_TRIM PIDs are not as specified:
• Inspect the A/F sensor. (See AIR FUEL RATIO (A/F) SENSOR INSPECTION [SKYACTIV-G (WITH CYLINDER DEACTIVATION (US))].) (See AIR FUEL RATIO (A/F) SENSOR INSPECTION [SKYACTIV-G (WITHOUT CYLINDER DEACTIVATION (US))].)
HO2S_OUT_VOLT PID is not as specified:
• Inspect the HO2S. (See HEATED OXYGEN SENSOR (HO2S) INSPECTION [SKYACTIV-G (WITH CYLINDER DEACTIVATION (US))].) (See HEATED OXYGEN SENSOR (HO2S) INSPECTION [SKYACTIV-G (WITHOUT CYLINDER DEACTIVATION (US))].)
Repair or replace the malfunctioning location.
• If the malfunction remains:
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5
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DETERMINE IF MALFUNCTION CAUSE IS A/C REQUEST SIGNAL OR OTHER
• Access the A/C_REQ PID using the M-MDS. (See PID/DATA MONITOR INSPECTION.)
• Monitor the A/C_REQ PID while turning on and off the air conditioner using the switch on the control panel.
• Does the A/C_REQ PID value change from on to off according to switch control panel?
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Yes
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Go to the next step.
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No
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If the A/C_REQ PID is always ON:
• Perform the symptom troubleshooting “A/C IS ALWAYS ON OR A/C COMPRESSOR RUNS CONTINUOUSLY”. (See A/C IS ALWAYS ON OR A/C COMPRESSOR RUNS CONTINUOUSLY [SKYACTIV-G].)
If the A/C_REQ PID is always OFF:
• Perform the symptom troubleshooting “A/C DOES NOT WORK SUFFICIENTLY”. (See A/C DOES NOT WORK SUFFICIENTLY [SKYACTIV-G].)
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6
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INSPECT DRIVE-BY-WIRE CONTROL SYSTEM OPERATION
• Perform the Electronic Control Throttle Operation Inspection. (See ENGINE CONTROL SYSTEM OPERATION INSPECTION [SKYACTIV-G (US)].)
• Does the drive-by-wire control system work properly?
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Yes
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Visually inspect the throttle body (damage/scratching).
• If there is any malfunction:
• If there is no malfunction:
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No
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Repair or replace the malfunctioning location and perform the repair completion verification.
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7
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INSPECT FUEL INJECTOR OPERATION
• Perform the Fuel Injector Operation Inspection. (See FUEL INJECTOR INSPECTION [SKYACTIV-G (WITH CYLINDER DEACTIVATION (US))].) (See FUEL INJECTOR INSPECTION [SKYACTIV-G (WITHOUT CYLINDER DEACTIVATION (US))].)
• Do the fuel injectors operate properly?
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Yes
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Go to the next step.
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No
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Repair or replace the malfunctioning location and perform the repair completion verification.
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8
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INSPECT PURGE CONTROL SYSTEM OPERATION
• Perform the Purge Control System Inspection. (See PURGE SOLENOID VALVE INSPECTION [SKYACTIV-G (WITH CYLINDER DEACTIVATION (US))].) (See PURGE SOLENOID VALVE INSPECTION [SKYACTIV-G (WITHOUT CYLINDER DEACTIVATION (US))].)
• Does the purge solenoid valve work properly?
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Yes
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Go to the next step.
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No
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Repair or replace the malfunctioning location and perform the repair completion verification.
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9
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INSPECT RELATED PART CONDITION
• Inspect the following:
• Is there any malfunction?
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Yes
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Repair or replace the malfunctioning location and perform the repair completion verification.
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No
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Go to the next step.
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10
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INSPECT FUEL PRESSURE (HIGH-SIDE)
• Start the engine and warm it up completely.
• Access the FUEL_PRES PID using the M-MDS at idle. (See PID/DATA MONITOR INSPECTION.)
• Is the FUEL_PRES PID value within specification?
Specification:
• Approx. 3 MPa {31 kgf/cm2, 435 psi} (Thailand specs.)
• Approx. 10 MPa {102 kgf/cm2, 1450 psi} (except Thailand specs.)
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Yes
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Go to Step 14.
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No
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Lower than specification:
• Inspect the following:
• If there is any malfunction:
• If there is no malfunction:
Higher than specification:
• Go to the next step.
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11
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DETERMINE IF MALFUNCTION CAUSE IS FUEL PRESSURE SENSOR OR HIGH PRESSURE FUEL PUMP
• Is the vehicle acceleration performance normal?
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Yes
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Go to the next step.
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No
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Go to Step 13.
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12
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INSPECT FUEL PRESSURE SENSOR FOR MALFUNCTION
• Inspect the applicable part. (See FUEL PRESSURE SENSOR INSPECTION [SKYACTIV-G (WITH CYLINDER DEACTIVATION (US))].) (See FUEL PRESSURE SENSOR INSPECTION [SKYACTIV-G (WITHOUT CYLINDER DEACTIVATION (US))].)
• Is the part normal?
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Yes
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Go to Step 14.
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No
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Replace the fuel distributor and perform the repair completion verification.
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13
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INSPECT SPILL VALVE CONTROL SOLENOID VALVE CONTROL CIRCUIT FOR SHORT TO GROUND
• Inspect the applicable circuit for a short to ground. (See CIRCUIT INSPECTION.)
• Is the circuit normal?
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Yes
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Replace the high pressure fuel pump and perform the repair completion verification.
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No
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Repair or replace the malfunctioning location and perform the repair completion verification.
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14
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INSPECT FUEL PRESSURE (LOW-SIDE)
• Connect the fuel pressure gauge between fuel pump and high pressure fuel pump.
• Measure the low side fuel pressure. (See FUEL LINE PRESSURE INSPECTION [SKYACTIV-G (WITH CYLINDER DEACTIVATION (US))].) (See FUEL LINE PRESSURE INSPECTION [SKYACTIV-G (WITHOUT CYLINDER DEACTIVATION (US))].)
• Is the low side fuel pressure within specification?
Specification:
• 475—555 kPa {4.85—5.65 kgf/cm2, 68.9—80.4 psi}
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Yes
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Go to the next step.
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No
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Inspect the following:
• Fuel line restriction
• Fuel filter clogged
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15
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INSPECT ENGINE COMPRESSION
• Measure the compression pressure for each cylinder. (See COMPRESSION INSPECTION [SKYACTIV-G (WITH CYLINDER DEACTIVATION (US))].) (See COMPRESSION INSPECTION [SKYACTIV-G (WITHOUT CYLINDER DEACTIVATION (US))].)
• Are compression pressures within specification?
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Yes
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Go to Step 21.
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No
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Go to the next step.
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16
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INSPECT ELECTRIC VARIABLE VALVE TIMING DRIVER FOR MALFUNCTION
• Inspect the applicable part. (See ELECTRIC VARIABLE VALVE TIMING MOTOR/DRIVER INSPECTION [SKYACTIV-G (WITH CYLINDER DEACTIVATION (US))].) (See ELECTRIC VARIABLE VALVE TIMING MOTOR/DRIVER INSPECTION [SKYACTIV-G (WITHOUT CYLINDER DEACTIVATION (US))].)
• Is the part normal?
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Yes
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Go to the next step.
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No
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Repair or replace the malfunctioning location and perform the repair completion verification.
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17
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INSPECT ELECTRIC VARIABLE VALVE TIMING MOTOR FOR MALFUNCTION
• Inspect the applicable part. (See ELECTRIC VARIABLE VALVE TIMING MOTOR/DRIVER INSPECTION [SKYACTIV-G (WITH CYLINDER DEACTIVATION (US))].) (See ELECTRIC VARIABLE VALVE TIMING MOTOR/DRIVER INSPECTION [SKYACTIV-G (WITHOUT CYLINDER DEACTIVATION (US))].)
• Is the part normal?
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Yes
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Go to the next step.
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No
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Repair or replace the malfunctioning location and perform the repair completion verification.
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18
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INSPECT ELECTRIC VARIABLE VALVE TIMING ACTUATOR FOR MALFUNCTION
• Inspect the applicable part. (See ELECTRIC VARIABLE VALVE TIMING ACTUATOR INSPECTION [SKYACTIV-G (WITH CYLINDER DEACTIVATION (US))].) (See ELECTRIC VARIABLE VALVE TIMING ACTUATOR INSPECTION [SKYACTIV-G (WITHOUT CYLINDER DEACTIVATION (US))].)
• Is the part normal?
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Yes
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Go to the next step.
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No
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Repair or replace the malfunctioning location and perform the repair completion verification.
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19
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INSPECT HYDRAULIC VARIABLE VALVE TIMING CONTROL SYSTEM OPERATION
• Perform the Hydraulic Variable Valve Timing Control System Operation Inspection. (See OCV FOR HYDRAULIC VARIABLE VALVE TIMING SYSTEM INSPECTION [SKYACTIV-G (WITH CYLINDER DEACTIVATION (US))].) (See OIL CONTROL VALVE (OCV) INSPECTION [SKYACTIV-G (WITHOUT CYLINDER DEACTIVATION (US))].)
• Is there any malfunction?
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Yes
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Repair or replace the malfunctioning location and perform the repair completion verification.
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No
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Go to the next step.
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20
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INSPECT FOR MALFUNCTION DUE TO DEVIATED VALVE TIMING
• Inspect the valve timing (timing chain installation condition). (See TIMING CHAIN REMOVAL/INSTALLATION [SKYACTIV-G (WITH CYLINDER DEACTIVATION (US))].) (See TIMING CHAIN REMOVAL/INSTALLATION [SKYACTIV-G (WITHOUT CYLINDER DEACTIVATION (US))].)
• Is the valve timing normal?
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Yes
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Inspect for the following engine internal parts:
• Cylinder
• Piston ring
• Intake valve
• Exhaust valve
• Such as cylinder head gasket
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No
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Adjust the valve timing to the correct timing and perform the repair completion verification.
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21
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INSPECT IGNITION SYSTEM OPERATION
• Perform the Spark Test. (See SPARK INSPECTION [SKYACTIV-G (WITH CYLINDER DEACTIVATION (US))].) (See SPARK INSPECTION [SKYACTIV-G (WITHOUT CYLINDER DEACTIVATION (US))].)
• Is a strong blue spark visible at each cylinder?
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Yes
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Go to the next step.
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No
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Repair or replace the malfunctioning location and perform the repair completion verification.
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22
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INSPECT EXHAUST SYSTEM FOR RESTRICTION
• Inspect for restriction in the exhaust system and the TWC.
• Is there any restriction?
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Yes
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Repair or replace the malfunctioning location and perform the repair completion verification.
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No
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Go to the next step.
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23
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INSPECT IF MALFUNCTION CAUSE IS PCV VALVE OR INJECTOR DRIVER (PCM INTEGRATED)
• Inspect the PCV valve. (See POSITIVE CRANKCASE VENTILATION (PCV) VALVE INSPECTION [SKYACTIV-G (WITH CYLINDER DEACTIVATION (US))].) (See POSITIVE CRANKCASE VENTILATION (PCV) VALVE INSPECTION [SKYACTIV-G (WITHOUT CYLINDER DEACTIVATION (US))].)
• Is there any malfunction?
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Yes
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Replace the PCV valve and perform the repair completion verification.
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No
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Injector driver malfunction.
• Replace the PCM. (See PCM REMOVAL/INSTALLATION [SKYACTIV-G (WITH CYLINDER DEACTIVATION (US))].) (See PCM REMOVAL/INSTALLATION [SKYACTIV-G (WITHOUT CYLINDER DEACTIVATION (US))].)
If the problem remains, overhaul the engine and perform the repair completion verification.
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Repair completion verification 1
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VERIFY THAT VEHICLE IS REPAIRED
• Install/connect the part removed/disconnected during the troubleshooting procedure.
• Has the malfunction symptom been eliminated?
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Yes
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Complete the symptom troubleshooting. (Explain contents of repair to customer)
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No
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Refer to the controller area network (CAN) malfunction diagnosis flow to inspect for a CAN communication error.
• If the CAN communication is normal, perform the diagnosis from Step 1.
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Repair completion verification 2
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VERIFY IF MALFUNCTION IS CAUSED BY NOT PERFORMING PCM REPROGRAMMING
• Verify repair information and verify that there is a new calibration in the PCM.
• Is there a new calibration in the PCM?
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Yes
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Perform the PCM reprogramming and verify if the malfunction symptom was corrected.
• If the malfunction recurs, replace the PCM. (See PCM REMOVAL/INSTALLATION [SKYACTIV-G (WITH CYLINDER DEACTIVATION (US))].) (See PCM REMOVAL/INSTALLATION [SKYACTIV-G (WITHOUT CYLINDER DEACTIVATION (US))].)
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No
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Replace the PCM.
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