Diagnostic Procedure

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ENGINE RUNS ROUGH/ROLLING IDLE (VIN Y) DIAGNOSTIC PROCEDURE

Step	Inspection	Results	Action
1	VERIFY IF MALFUNCTION INCLUDES HARD ENGINE STARTING Verify the vehicle engine condition. Can idling be maintained?	Yes	Go to the next step.
1		No	Perform the symptom troubleshooting [ENGINE STALLS AFTER START/AT IDLE]. (See ENGINE STALLS-AFTER START/AT IDLE (VIN Y) .)
2	DETERMINE IF MALFUNCTION CAUSE IS OVERHEATING OR OTHER WARNING: Observe legal speed limits when driving the vehicle and perform the procedure in a location where safety can be assured. To prevent an accident, work with two people when the vehicle is being driven (one person drives vehicle, other person operates MMDS). Access the PCM PID [ECT] using the MMDS. Is the PID value less than 116°C {241°F} during driving?	Yes	Go to the next step.
2		No	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 (VIN Y) .)
3	VERIFY PCM DTCs Perform the DTC inspection for the PCM. (See DTC INSPECTION .) Are any DTCs displayed?	Yes	Repair or replace the malfunctioning location according to the applicable DTC troubleshooting. (See DTC TABLE [PCM (VIN Y)] .)
3		No	Go to the next step.
4	VERIFY CURRENT INPUT SIGNAL STATUS WARNING: Observe legal speed limits when driving the vehicle and perform the procedure in a location where safety can be assured. To prevent an accident, work with two people when the vehicle is being driven (one person drives vehicle, other person operates MMDS). Access the following PIDs using the MMDS: PCM: APP1 APP2 ECT ECT_VOLT MAF MAP MAP_VOLT A/F_SEN_CUR HO2S_OUT_VOLT SHRT_FUEL_TRIM LONG_FUEL_TRIM Do the PIDs indicate the correct values under the malfunction condition? (See PID/DATA MONITOR TABLE [PCM (VIN Y)] .)	Yes	Go to the next step.
4		No	APP1, APP2 PIDs are not as specified: Inspect the APP sensor No. 1 and No. 2. (Refer to ACCELERATOR PEDAL POSITION (APP) SENSOR INSPECTION (VIN Y) .) ECT, ECT_VOLT PIDs are not as specified: Inspect the ECT sensor. (Refer to ENGINE COOLANT TEMPERATURE (ECT) SENSOR INSPECTION (VIN Y) .) MAF PID is not as specified: Inspect the MAF sensor. (Refer to MASS AIR FLOW (MAF) SENSOR INSPECTION (VIN Y) .) MAP, MAP_VOLT PIDs are not as specified: Inspect the MAP sensor. (Refer to MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR INSPECTION (VIN Y) .) A/F_SEN_CUR, SHRT_FUEL_TRIM, LONG_FUEL_TRIM PIDs are not as specified: Inspect the A/F sensor. (Refer to AIR FUEL RATIO (A/F) SENSOR INSPECTION (VIN Y) .) HO2S_OUT_VOLT PID is not as specified: Inspect the HO2S. (Refer to HEATED OXYGEN SENSOR (HO2S) INSPECTION (VIN Y) .) Repair or replace the malfunctioning location. If the malfunction remains: Perform the [Action for Non-repeatable Malfunction] procedure. (See TROUBLESHOOTING PROCEDURE .)
5	DETERMINE IF MALFUNCTION CAUSE IS A/C REQUEST SIGNAL OR OTHER Access the PCM [A/C_REQ] PID using the M-MDS. 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 Yes to No according to switch control panel?	Yes	Go to the next step.
5		No	If the A/C_REQ PID is always Yes: Perform the symptom troubleshooting [A/C IS ALWAYS ON OR A/C COMPRESSOR RUNS CONTINUOUSLY]. If the A/C_REQ PID is always No: Perform the symptom troubleshooting [A/C DOES NOT WORK SUFFICIENTLY].
6	INSPECT DRIVE-BY-WIRE CONTROL SYSTEM OPERATION Perform the Electronic Control Throttle Operation Inspection. (See ENGINE CONTROL SYSTEM OPERATION INSPECTION (VIN Y) .) Does the drive-by-wire control system work properly?	Yes	Visually inspect the throttle body (damage/scratching). If there is any malfunction: Repair or replace the malfunctioning location and perform the repair completion verification 1. If there is no malfunction: Go to the next step.
6		No	Repair or replace the malfunctioning location and perform the repair completion verification 1.
7	INSPECT FUEL INJECTOR OPERATION Perform the Fuel Injector Operation Inspection. (Refer to FUEL INJECTOR INSPECTION (VIN Y) .) Do the fuel injectors operate properly?	Yes	Go to the next step.
7		No	Repair or replace the malfunctioning location and perform the repair completion verification 1.
8	INSPECT PURGE CONTROL SYSTEM OPERATION Perform the Purge Control System Inspection. (Refer to PURGE SOLENOID VALVE INSPECTION (VIN Y) .) Does the purge solenoid valve work properly?	Yes	Go to the next step.
8		No	Repair or replace the malfunctioning location and perform the repair completion verification 1.
9	INSPECT RELATED PART CONDITION Inspect the following: Poor fuel quality (proper octane, contamination, winter/summer blend) Air leakage from intake-air system Intake-air system restriction Electrical connector disconnected Fuel leakage in fuel system Vacuum leakage Engine oil viscosity CKP sensor and intake CMP sensor Installation condition (Refer to CRANKSHAFT POSITION (CKP) SENSOR REMOVAL/INSTALLATION (VIN Y) .) (Refer to CAMSHAFT POSITION (CMP) SENSOR REMOVAL/INSTALLATION (VIN Y) .) Damaged trigger wheel (intake camshaft) Exhaust CMP sensor Installation condition (Refer to CAMSHAFT POSITION (CMP) SENSOR REMOVAL/INSTALLATION (VIN Y) .) Damaged trigger wheel (exhaust camshaft) Is there any malfunction?	Yes	Repair or replace the malfunctioning location and perform the repair completion verification 1.
9		No	Go to the next step.
10	INSPECT FUEL PRESSURE (HIGH-SIDE) Start the engine and warm it up completely. Access the PCM PID [FUEL_PRES] using the M-MDS at idle. Is the PID value within specification? Specification: Approx. 10 MPa {102 kgf/cm ² , 1450 psi}	Yes	Go to Step 14.
10		No	Lower than specification: Inspect the following: Fuel leakage at the fuel line and fuel injector Fuel pump Perform the Fuel Pump (Low-pressure side) Operation Inspection. (Refer to FUEL PUMP OPERATION INSPECTION .) High fuel pressure sensor (Refer to HIGH FUEL PRESSURE SENSOR INSPECTION (VIN Y) .) High pressure fuel pump (Refer to HIGH PRESSURE FUEL PUMP INSPECTION (VIN Y) .) If there is any malfunction: Repair or replace the malfunctioning location and perform the repair completion verification 1. If there is no malfunction: Go to Step 13. Higher than specification: Go to the next step.
11	DETERMINE IF MALFUNCTION CAUSE IS HIGH FUEL PRESSURE SENSOR OR HIGH PRESSURE FUEL PUMP Is the vehicle acceleration performance normal?	Yes	Go to the next step.
11		No	Go to Step 13.
12	VERIFY HIGH FUEL PRESSURE SENSOR FOR MALFUNCTION Inspect the applicable part. (Refer to HIGH FUEL PRESSURE SENSOR INSPECTION (VIN Y) .) Is the part normal?	Yes	Go to Step 14.
12		No	Repair or replace the malfunctioning location and perform the repair completion verification 1. (Refer to FUEL INJECTOR REMOVAL/INSTALLATION (VIN Y) .)
13	INSPECT WIRING HARNESS (INCLUDING CONNECTOR/TERMINAL) BETWEEN PCM AND SPILL VALVE CONTROL SOLENOID VALVE (HIGH PRESSURE FUEL PUMP) FOR MALFUNCTION Inspect the applicable circuit. (see CIRCUIT INSPECTION .) (see CONNECTOR INSPECTION .) Is the circuit normal?	Yes	Replace the high pressure fuel pump and perform the repair completion verification 1. (Refer to HIGH PRESSURE FUEL PUMP INSPECTION (VIN Y) .)
13		No	Repair or replace the malfunctioning location and perform the repair completion verification 1.
14	INSPECT FUEL PRESSURE (LOW-SIDE) Connect the fuel pressure gauge between fuel pump and high pressure fuel pump. Measure the low side fuel pressure. (Refer to FUEL LINE PRESSURE INSPECTION (VIN Y) .) Is the low side fuel pressure within specification? Specification: 475-555 kPa {4.85-5.65 kgf/cm ² , 68.9-80.4 psi}	Yes	Go to the next step.
14		No	Inspect the following: Fuel line restriction Fuel filter clogged If there is any malfunction: Repair or replace the malfunctioning location and perform the repair completion verification 1. If there is no malfunction: Replace the fuel pump unit and perform the repair completion verification 1. (Refer to FUEL PUMP UNIT REMOVAL/INSTALLATION (VIN Y) .)
15	INSPECT ENGINE COMPRESSION Measure the compression pressure for each cylinder. (Refer to COMPRESSION INSPECTION (VIN Y) .) Are compression pressures within specification?	Yes	Go to Step 21.
15		No	Go to the next step.
16	VERIFY ELECTRIC VARIABLE VALVE TIMING DRIVER FOR MALFUNCTION Inspect the applicable part. (Refer to ELECTRIC VARIABLE VALVE TIMING MOTOR/DRIVER INSPECTION (VIN Y) .) Is the part normal?	Yes	Go to the next step.
16		No	Repair or replace the malfunctioning location and perform the repair completion verification 1. (Refer to ELECTRIC VARIABLE VALVE TIMING MOTOR/DRIVER REMOVAL/INSTALLATION (VIN Y) .)
17	VERIFY ELECTRIC VARIABLE VALVE TIMING MOTOR FOR MALFUNCTION Inspect the applicable part. (Refer to ELECTRIC VARIABLE VALVE TIMING MOTOR/DRIVER INSPECTION (VIN Y) .) Is the part normal?	Yes	Go to the next step.
17		No	Repair or replace the malfunctioning location and perform the repair completion verification 1. (Refer to ELECTRIC VARIABLE VALVE TIMING MOTOR/DRIVER REMOVAL/INSTALLATION (VIN Y) .)
18	VERIFY ELECTRIC VARIABLE VALVE TIMING ACTUATOR FOR MALFUNCTION Inspect the applicable part. (Refer to ELECTRIC VARIABLE VALVE TIMING ACTUATOR INSPECTION (VIN Y) .) Is the part normal?	Yes	Go to the next step.
18		No	Repair or replace the malfunctioning location and perform the repair completion verification 1. (Refer to ELECTRIC VARIABLE VALVE TIMING ACTUATOR, HYDRAULIC VARIABLE VALVE TIMING ACTUATOR REMOVAL/INSTALLATION (VIN Y) .)
19	INSPECT HYDRAULIC VARIABLE VALVE TIMING CONTROL SYSTEM OPERATION Perform the Hydraulic Variable Valve Timing Control System Operation Inspection. (Refer to OIL CONTROL VALVE (OCV) INSPECTION (VIN Y) .) Is there any malfunction?	Yes	Repair or replace the malfunctioning location and perform the repair completion verification 1.
19		No	Go to the next step.
20	INSPECT FOR MALFUNCTION DUE TO DEVIATED VALVE TIMING Inspect the valve timing (timing chain installation condition). (Refer to TIMING CHAIN REMOVAL/INSTALLATION (VIN Y) .) Is the valve timing normal?	Yes	Inspect for the following engine internal parts: Cylinder Piston ring Intake valve Exhaust valve Such as cylinder head gasket If there is any malfunction: Repair or replace the malfunctioning location and perform the repair completion verification 1.
20		No	Adjust the valve timing to the correct timing and perform the repair completion verification 1.
21	INSPECT IGNITION SYSTEM OPERATION Perform the Spark Test. (Refer to SPARK INSPECTION (VIN Y) .) Is a strong blue spark visible at each cylinder?	Yes	Go to the next step.
21		No	Repair or replace the malfunctioning location and perform the repair completion verification 1.
22	INSPECT EXHAUST SYSTEM FOR RESTRICTION Inspect for restriction in the exhaust system and the TWC. Is there any restriction?	Yes	Repair or replace the malfunctioning location and perform the repair completion verification 1.
22		No	Go to the next step.
23	INSPECT IF MALFUNCTION CAUSE IS PCV VALVE OR INJECTOR DRIVER (PCM INTEGRATED) Inspect the PCV valve. (Refer to POSITIVE CRANKCASE VENTILATION (PCV) VALVE INSPECTION (VIN Y) .) Is there any malfunction?	Yes	Replace the PCV valve and perform the repair completion verification 1. (Refer to POSITIVE CRANKCASE VENTILATION (PCV) VALVE REMOVAL/INSTALLATION (VIN Y) .)
23		No	Injector driver malfunction. Replace the PCM. (Refer to PCM REMOVAL/INSTALLATION (VIN Y) .) If the problem remains, overhaul the engine and perform the repair completion verification 1.
Repair completion verification 1	VERIFY THAT VEHICLE IS REPAIRED Install/connect the part removed/disconnected during the troubleshooting procedure. Has the malfunction symptom been eliminated?	Yes	Complete the symptom troubleshooting. (Explain contents of repair to customer)
Repair completion verification 1		No	Refer to the controller area network (CAN) malfunction diagnosis flow to inspect for a CAN communication error. (See MALFUNCTION DIAGNOSIS FLOW [CONTROLLER AREA NETWORK (CAN)] .) If the CAN communication is normal, perform the diagnosis from Step 1. If the malfunction recurs, replace the PCM. (Refer to PCM REMOVAL/INSTALLATION (VIN Y) .)