Diagnostic Procedure

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LOW IDLE/STALLS DURING DECELERATION (PYUL) DIAGNOSTIC PROCEDURE

Step	Inspection	Results	Action
1	VERIFY IF MALFUNCTION INCLUDES HARD ENGINE STARTING Is the engine unable to start after it has stalled? NOTE: If the ignition is not switched off or ACC after the engine stalls, and then an engine restart is attempted, the PCM corrects the difference between CKP sensor and CMP sensor signals caused by engine stalling, which may result in more time needed to restart the engine.	Yes	If the engine is unable to start, perform the symptom troubleshooting [WILL NOT CRANK] and [CRANKS NORMALLY BUT WILL NOT START]. (See WILL NOT CRANK [PYUL] ). (See CRANKS NORMALLY BUT WILL NOT START [PYUL] ).
1		No	Go to the next step.
2	VERIFY IF MALFUNCTION INCLUDES ROUGH IDLING Does the engine idle rough?	Yes	Perform the symptom troubleshooting [ENGINE RUNS ROUGH/ROLLING IDLE]. (See ENGINE RUNS ROUGH/ROLLING IDLE [PYUL] ).
2		No	Go to the next step.
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 (PYUL)] .)
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 M-MDS). Access the following PIDs using the M-MDS: (See PID/DATA MONITOR INSPECTION .) PCM: APP1 APP2 ECT ECT_VOLT MAF MAP MAP_VOLT TP1 TP2 A/F_SEN_CUR HO2S_OUT_VOLT SHRT_FUEL_TRIM LONG_FUEL_TRIM ALT_VOLT_OUT_ACT Electrical supply unit (ESU): BRK_SW Do the PIDs indicate the correct values under the malfunction condition? (See PID/DATA MONITOR TABLE [PCM (PYUL)] .) (See PID/DATA MONITOR TABLE [ESU] .)	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 ] in Service Information). ECT, ECT_VOLT PIDs are not as specified: Inspect the ECT sensor. (Refer to [ENGINE COOLANT TEMPERATURE (ECT) SENSOR INSPECTION ] in Service Information). MAF PID is not as specified: Inspect the MAF sensor. (Refer to [MASS AIR FLOW (MAF) SENSOR INSPECTION ] in Service Information). MAP, MAP_VOLT PIDs are not as specified: Inspect the MAP sensor. (Refer to [MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR INSPECTION ] in Service Information). TP1, TP2 PIDs are not as specified: Inspect the TP sensor. (Refer to [THROTTLE POSITION (TP) SENSOR INSPECTION ] in Service Information). 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 ] in Service Information). HO2S_OUT_VOLT PID is not as specified: Inspect the HO2S. (Refer to [HEATED OXYGEN SENSOR (HO2S) INSPECTION ] in Service Information). ALT_VOLT_OUT_ACT PID is not as specified: Inspect the generator. (Refer to [ GENERATOR INSPECTION] in Service Information). BRK_SW PID is not as specified: Inspect the brake switch. (Refer to [BRAKE SWITCH INSPECTION ] in Service Information). Repair or replace the malfunctioning location. If the malfunction remains: Inspect communication error between TCM and PCM. Repair or replace the malfunctioning location and perform the repair completion verification 1. 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. (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 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	DETERMINE IF MALFUNCTION CAUSE IS DRIVE-BY-WIRE CONTROL SYSTEM OR OTHER Will the engine run smoothly at part throttle?	Yes	Go to Step 8.
6		No	Go to the next step.
7	INSPECT DRIVE-BY-WIRE CONTROL SYSTEM OPERATION Perform [Electronic Control Throttle Operation Inspection]. (See ENGINE CONTROL SYSTEM OPERATION INSPECTION [PYUL] ). 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.
7		No	Repair or replace the malfunctioning location and perform the repair completion verification 1.
8	INSPECT FUEL INJECTOR OPERATION Perform [Fuel Injector Operation Inspection]. (Refer to [FUEL INJECTOR INSPECTION ] in Service Information). Do the fuel injectors operate properly?	Yes	Go to the next step.
8		No	Repair or replace the malfunctioning location and perform the repair completion verification 1.
9	INSPECT PURGE CONTROL SYSTEM OPERATION Perform [Purge Control System Inspection]. (Refer to [PURGE SOLENOID VALVE INSPECTION ] in Service Information). Does the purge solenoid valve work properly?	Yes	Go to the next step.
9		No	Repair or replace the malfunctioning location and perform the repair completion verification 1.
10	INSPECT RELATED PART CONDITION Inspect the following: Poor fuel quality (proper octane, contamination, winter/summer blend) Intake-air system leakage or restriction Fuel leakage in fuel system Vacuum leakage Engine mount installation loose CKP sensor, intake CMP sensor and exhaust CMP sensor Installation condition (Refer to [CRANKSHAFT POSITION (CKP) SENSOR REMOVAL/INSTALLATION ] in Service Information). (Refer to [CAMSHAFT POSITION (CMP) SENSOR REMOVAL/INSTALLATION ] in Service Information). Damaged trigger wheel, intake camshaft and exhaust camshaft Is there any malfunction?	Yes	Repair or replace the malfunctioning location and perform the repair completion verification 1.
10		No	Go to the next step.
11	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. (See PID/DATA MONITOR INSPECTION .) Is the PID value within specification? Specification: Approx. 10 MPa {102 kgf/cm² , 1450 psi}	Yes	Go to Step 15.
11		No	Lower than specification: Inspect the following: Fuel leakage at the fuel line and fuel injector Fuel pump Perform [Fuel Pump (Low-pressure side) Operation Inspection]. (Refer to [HIGH PRESSURE FUEL PUMP INSPECTION ] in Service Information). Fuel pressure sensor (Refer to [FUEL PRESSURE SENSOR INSPECTION ] in Service Information). High pressure fuel pump (Refer to [HIGH PRESSURE FUEL PUMP INSPECTION ] in Service Information). 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 14. Higher than specification: Go to the next step.
12	DETERMINE IF MALFUNCTION CAUSE IS FUEL PRESSURE SENSOR OR HIGH PRESSURE FUEL PUMP Is the vehicle acceleration performance normal?	Yes	Go to the next step.
12		No	Go to Step 14.
13	VERIFY FUEL PRESSURE SENSOR FOR MALFUNCTION Inspect the applicable part. (Refer to [FUEL PRESSURE SENSOR INSPECTION ] in Service Information). Is the part normal?	Yes	Go to Step 15.
13		No	Replace the fuel distributor and perform the repair completion verification 1. (Refer to [FUEL INJECTOR REMOVAL/INSTALLATION ] in Service Information).
14	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 REMOVAL/INSTALLATION ] in Service Information).
14		No	Repair or replace the malfunctioning location and perform the repair completion verification 1.
15	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 ] in Service Information). Is the low side fuel pressure within specification? Specification: 475-555 kPa {4.85-5.65 kgf/cm² , 68.9-80.4 psi}	Yes	Go to the next step.
15		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 ] in Service Information).
16	INSPECT ENGINE COMPRESSION Measure the compression pressure for each cylinder. (Refer to [COMPRESSION INSPECTION ] in Service Information). Are compression pressures within specification?	Yes	Go to Step 22.
16		No	Go to the next step.
17	VERIFY ELECTRIC VARIABLE VALVE TIMING DRIVER FOR MALFUNCTION Inspect the applicable part. (Refer to [ELECTRIC VARIABLE VALVE TIMING MOTOR/DRIVER INSPECTION ] in Service Information). 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 ] in Service Information).
18	VERIFY ELECTRIC VARIABLE VALVE TIMING MOTOR FOR MALFUNCTION Inspect the applicable part. (Refer to [ELECTRIC VARIABLE VALVE TIMING MOTOR/DRIVER INSPECTION ] in Service Information). 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 MOTOR/DRIVER REMOVAL/INSTALLATION ] in Service Information).
19	VERIFY ELECTRIC VARIABLE VALVE TIMING ACTUATOR FOR MALFUNCTION Inspect the applicable part. (Refer to [ELECTRIC VARIABLE VALVE TIMING ACTUATOR INSPECTION ] in Service Information). Is the part normal?	Yes	Go to the next step.
19		No	Repair or replace the malfunctioning location and perform the repair completion verification 1. (Refer to [ELECTRIC VARIABLE VALVE TIMING ACTUATOR REMOVAL/INSTALLATION ] in Service Information).
20	INSPECT HYDRAULIC VARIABLE VALVE TIMING CONTROL SYSTEM OPERATION Perform [Hydraulic Variable Valve Timing Control System Operation Inspection]. (Refer to [HYDRAULIC VARIABLE VALVE TIMING ACTUATOR INSPECTION ] in Service Information). Is there any malfunction?	Yes	Repair or replace the malfunctioning location and perform the repair completion verification 1.
20		No	Go to the next step.
21	INSPECT FOR MALFUNCTION DUE TO DEVIATED VALVE TIMING Inspect the valve timing (timing chain installation condition). (Refer to [TIMING CHAIN REMOVAL/INSTALLATION ] in Service Information). 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.
21		No	Adjust the valve timing to the correct timing and perform the repair completion verification 1.
22	INSPECT ENGINE MOUNT FOR LOOSENESS OR INJECTOR DRIVER (PCM INTEGRATED) Inspect the engine mount for looseness. Is the engine mount normal?	Yes	Go to the next step.
22		No	Repair or replace the malfunctioning location and perform the repair completion verification 1.
23	VERIFY TCM DTCs Perform the DTC inspection for the TCM. (See DTC INSPECTION .) Are any DTCs displayed?	Yes	Repair or replace the malfunctioning location according to the applicable DTC troubleshooting. (See DTC TABLE [TCM (NJ8A (X)-EC/NN8A (X)-EC/MM8A (X)-EC)] .)
23		No	Injector driver malfunction. Replace the PCM. (Refer to [PCM REMOVAL/INSTALLATION ] in Service Information). 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 ] in Service Information).