NO.8 ENGINE RUNS ROUGH/ROLLING IDLE [SKYACTIV-G 2.5 (WITH CYLINDER DEACTIVATION)]

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8

ENGINE RUNS ROUGH/ROLLING IDLE
DESCRIPTION
•  Idle speed lower than the specification.
•  Idling speed unstable, increases/decreases.
POSSIBLE CAUSE
•  Engine overheating
•  PCM DTC is stored
•  Erratic signal to PCM
―  APP sensor or related circuit malfunction
―  ECT sensor or related circuit malfunction
―  MAF sensor or related circuit malfunction
―  MAP sensor or related circuit malfunction
―  A/F sensor or related circuit malfunction
―  HO2S or related circuit malfunction
―  Improper air/fuel mixture ratio control operation
•  Improper load signal input
―  Improper A/C request signal
•  Improper operation of A/C system
•  Improper operation of drive-by-wire control system
•  Incorrect fuel injection timing
•  Unbalanced fuel injection amount for each cylinder
•  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 or no signal from CMP sensor
―  Loose installation
―  Damaged trigger wheel (intake camshaft and/or exhaust camshaft)
―  Open or short circuit in related wiring harness
•  Erratic signal from CKP sensor
―  Loose installation
―  Damaged trigger wheel (crankshaft pulley)
―  Open or short circuit in related wiring harness
•  Inadequate fuel pressure (high or low pressure side)
―  Fuel pressure sensor or related circuit malfunction
―  High pressure fuel pump malfunction
―  Spill valve control solenoid valve control circuit malfunction (damage to driver in PCM caused by short circuit to ground system)
―  Spill valve control solenoid valve (built-into high pressure fuel pump) malfunction
―  Relief valve (built-into high pressure fuel pump) malfunction
―  Fuel pump (low-side) body mechanical malfunction
―  Fuel filter clogged
―  Fuel injector malfunction
•  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 or excessive unbalance for each cylinder
•  Improper intake valve timing
•  Improper exhaust valve timing
•  Spark plug malfunction
•  Ignition coil malfunction
•  Exhaust system or TWC restricted
•  PCV valve malfunction
•  Injector driver (built-into PCM) malfunction
POSSIBLE CAUSE
Warning
The following troubleshooting flow chart contains the fuel system diagnosis and repair procedures. Read the following warnings before performing the fuel system services:
•  Fuel vapor is hazardous. It can easily ignite, causing serious injury and damage. Always keep sparks and flames away from fuel.
•  Fuel line spills and leakage are dangerous. Fuel can ignite and cause serious injury or death and damage. Fuel can also irritate skin and eyes. To prevent this, always complete “BEFORE SERVICE PRECAUTION” and “AFTER SERVICE PRECAUTION” described in this manual. (See BEFORE SERVICE PRECAUTION [SKYACTIV-G 2.5 (WITH CYLINDER DEACTIVATION)].) (See AFTER SERVICE PRECAUTION [SKYACTIV-G 2.5 (WITH CYLINDER DEACTIVATION)].)
Caution
•  Disconnecting/connecting the quick release connector without cleaning it may possibly cause damage to the fuel pipe and quick release connector. Always clean the quick release connector joint area before disconnecting/connecting, and make sure that it is free of foreign matter.

Caution
•  Verify the malfunction symptom according to not only the PID value but also the symptom troubleshooting.

Related PIDs

Item (definition)

Unit/Condition

Definition

Condition/Specification (Reference)
AC_REQ
Off/On
A/C request signal
•  A/C switch off: Off
•  A/C switch on: On
APP1
%
APP sensor No.1
•  Accelerator pedal released: Approx. 15%
•  Accelerator pedal depressed: Approx. 90.58%
V
•  Accelerator pedal released: Approx. 0.75 V
•  Accelerator pedal depressed: Approx. 4.52 V
APP2
%
APP sensor No.2
•  Accelerator pedal released: Approx. 7.45%
•  Accelerator pedal depressed: Approx. 45.49%
V
•  Accelerator pedal released: Approx. 0.38 V
•  Accelerator pedal depressed: Approx. 2.26 V
ECT
°C, °F
Engine coolant temperature
•  Displays ECT
V
•  ECT is 20 °C {68 °F}: Approx. 3.10 V
•  ECT is 40 °C {104 °F}: Approx. 2.16 V
•  ECT is 60 °C {140 °F}: Approx. 1.40 V
•  ECT is 80 °C {176 °F}: Approx. 0.87 V
•  ECT is 100 °C {212 °F}: Approx. 0.54 V
FUEL_PRES
KPa {MPa}, mBar {Bar}, psi, in H20
Fuel pressure
•  Displays fuel pressure
V
Idle (ECT 80 °C {176 °F})
•  Fuel pressure is 10 MPa {102 kgf/cm2, 1450 psi}: Approx. 1.4 V
LOAD
%
Engine load
•  Idle (after warm up): Approx. 16.07%
•  Racing (engine speed is 2,000 rpm): Approx. 13.33%
•  Racing (engine speed is 4,000 rpm): Approx. 15.29%
LONGFT1
%
Long term fuel trim
•  Idle (after warm up): Approx. -3.9%
•  Racing (engine speed is 2,000 rpm): Approx. -0.78%
•  Racing (engine speed is 4,000 rpm): Approx. -0.78%
MAF
g/Sec
Mass air flow
•  Displays MAF
V
•  Ignition switched ON (engine off) (MAF: 0.00 g/s {0 lb/min}): Approx. 1.69 V (ECT is 53 °C {127 °F})
•  Idle (after warm up) (MAF: 2.50 g/s {0.331 lb/min}): Approx. 1.89 V (ECT is 93 °C {199 °F})
•  Racing (engine speed is 2,000 rpm) (MAF: 3.80 g/s {0.503 lb/min}): Approx. 2.02 V (ECT is 95 °C {203 °F})
MAP
KPa {MPa}, mBar {Bar}, psi, in H20
Manifold absolute pressure
•  Displays MAP
MAP_V
V
MAP sensor voltage
•  Ignition switched ON (engine off) (MAP:100 kPa {1.02 kgf/cm2, 14.5 psi}): Approx. 4.04 V
•  Idle (after warm up) (MAP: 35 kPa {0.36 kgf/cm2, 5.1 psi}): Approx. 1.40 V
•  Racing (engine speed is 2,000 rpm) (MAP: 26 kPa {0.27 kgf/cm2, 3.8 psi}): Approx. 1.01 V
O2S11
µA
A/F sensor
•  Idle (after warm up): Approx. -39 µA
•  Deceleration fuel cut (accelerator pedal released from engine speed of 4,000 rpm or more): Approx. 3.84 mA
O2S12
V
HO2S
•  Idle (after warm up): 0—1.0 V
•  Deceleration fuel cut (accelerator pedal released from engine speed of 4,000 rpm or more): Approx. 0 V
RPM
RPM
Engine speed
•  Displays engine speed
SHRTFT1
%
Short term fuel trim
•  Idle (after warm up): Approx. 2.34%
•  Racing (engine speed is 2,000 rpm): Approx. 3.9%
•  Racing (engine speed is 4,000 rpm): Approx. 1.56%
TP_REL
%
Throttle position signal (relative value)
•  Accelerator pedal released: Approx. 12%
•  Accelerator pedal depressed: Approx. 82%
VSS
KPH, MPH
Vehicle speed
•  Displays vehicle speed

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.
No
Perform the symptom troubleshooting “NO.5 ENGINE STALLS-AFTER START/AT IDLE”.
(See NO.5 ENGINE STALLS-AFTER START/AT IDLE [SKYACTIV-G 2.5 (WITH CYLINDER DEACTIVATION)].)
2
VERIFY IF MALFUNCTION CAUSE IS OVERHEATING
•  Access the ECT PID using the M-MDS.
Caution
•  While performing this step, always operate the vehicle in a safe and lawful manner.
•  When the M-MDS is used to observe monitor system status while driving, be sure to have another technician with you, or record the data in the M-MDS using the PID/DATA MONITOR AND RECORD capturing function and inspect later.
•  Is the ECT PID value less than 116 °C {241 °F} during driving?
Yes
Go to the next step.
No
The cause of this concern could be from the cooling system overheating.
•  Perform the symptom troubleshooting “NO.17 COOLING SYSTEM CONCERNS-OVERHEATING”.
3
VERIFY PCM DTC
•  Retrieve any DTCs using the M-MDS.
•  Are any DTCs present?
Yes
Go to the applicable DTC inspection.
(See DTC TABLE [PCM (SKYACTIV-G 2.5 (WITH CYLINDER DEACTIVATION))].)
No
Go to the next step.
4
VERIFY CURRENT INPUT SIGNAL STATUS
Caution
•  While performing this step, always operate the vehicle in a safe and lawful manner.
•  When the M-MDS is used to observe monitor system status while driving, be sure to have another technician with you, or record the data in the M-MDS using the PID/DATA MONITOR AND RECORD capturing function and inspect later.
•  Access the following PIDs using the M-MDS:
―  APP1
―  APP2
―  ECT
―  MAF
―  MAP
―  MAP_V
―  O2S11
―  O2S12
―  SHRTFT1
―  LONGFT1
•  Do the PIDs indicate the correct values under the malfunction condition?
Yes
Go to the next step.
No
APP1, APP2 PIDs are not as specified:
•  Inspect the APP sensor.
ECT PID is not as specified:
•  Inspect the ECT sensor.
MAF PID is not as specified:
•  Inspect the MAF sensor.
MAP, MAP_V PIDs are not as specified:
•  Inspect the MAP sensor.
O2S11, SHRTFT1, LONGFT1 PIDs are not as specified:
•  Inspect the A/F sensor.
O2S12 PID is not as specified:
•  Inspect the HO2S.
Repair or replace the malfunctioning part according to the inspection results.
•  If the malfunction remains:
―  Perform the “INTERMITTENT CONCERN TROUBLESHOOTING” procedure.
5
DETERMINE IF MALFUNCTION CAUSE IS A/C REQUEST SIGNAL OR OTHER
•  Access the AC_REQ PID using the M-MDS.
•  Monitor the AC_REQ PID while turning on and off the air conditioner using the switch on the control panel.
•  Does the AC_REQ PID value change from on to off according to switch control panel?
Yes
Go to the next step.
No
If the AC_REQ PID is always ON:
•  Perform the symptom troubleshooting “NO.24 A/C IS ALWAYS ON OR A/C COMPRESSOR RUNS CONTINUOUSLY”.
If the AC_REQ PID is always OFF:
•  Perform the symptom troubleshooting “NO.23 A/C DOES NOT WORK SUFFICIENTLY”.
6
INSPECT DRIVE-BY-WIRE CONTROL SYSTEM OPERATION
•  Perform the Electronic Control Throttle Operation Inspection.
•  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 part according to the inspection results.
•  If there is no malfunction:
―  Go to the next step.
No
Repair or replace the malfunctioning part according to the inspection results.
7
INSPECT FUEL INJECTOR OPERATION
•  Perform the Fuel Injector Operation Inspection.
•  Do the fuel injectors operate properly?
Yes
Go to the next step.
No
Repair or replace the malfunctioning part according to the inspection results.
8
INSPECT PURGE CONTROL SYSTEM OPERATION
•  Perform the Purge Control System Inspection.
•  Does the purge solenoid valve work properly?
Yes
Go to the next step.
No
Repair or replace the malfunctioning part according to the inspection results.
9
INSPECT RELATED PART CONDITION
•  Inspect the following:
―  Fuel quality (proper octane, contamination, winter/summer blend)
―  Intake-air system restriction or leakage
―  Electrical connectors connection
―  Fuel leakage in fuel system
―  Vacuum leakage
―  Engine oil viscosity
―  CKP sensor, intake CMP sensor and exhaust CMP sensor
•  Installation condition
•  Damaged trigger wheel, intake camshaft and exhaust camshaft
•  Is there any malfunction?
Yes
Service if necessary.
•  Repeat this step.
No
Go to the next step.
10
INSPECT FUEL PRESSURE (HIGH-SIDE)
•  Start the engine and warm it up completely.
•  Access the FUEL_PRES PID using the M-MDS at idle.
•  Is the FUEL_PRES PID value approx. 10 MPa {102 kgf/cm2, 1450 psi}?
Yes
Go to Step 14.
No
Lower than approx. 10 MPa {102 kgf/cm2, 1450 psi}:
•  Inspect the following:
―  Fuel leakage at the fuel line and fuel injector
―  Fuel pump
•  Perform the Fuel Pump (Low-pressure Side) Operation Inspection.
―  Fuel pressure sensor
―  High pressure fuel pump
•  If there is any malfunction:
―  Repair or replace the malfunctioning part according to the inspection results.
•  If there is no malfunction:
―  Go to Step 13.
Higher than approx. 10 MPa {102 kgf/cm2, 1450 psi}:
•  Go to the next step.
11
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.
No
Go to Step 13.
12
INSPECT FUEL PRESSURE SENSOR
•  Inspect the fuel pressure sensor.
•  Is there any malfunction?
Yes
Replace the fuel distributor.
(See FUEL INJECTOR REMOVAL/INSTALLATION [SKYACTIV-G 2.5 (WITH CYLINDER DEACTIVATION)].)
No
Go to Step 14.
13
INSPECT SPILL VALVE CONTROL SOLENOID VALVE CONTROL CIRCUIT FOR SHORT TO GROUND
•  Switch the ignition off.
•  Disconnect the high pressure fuel pump and PCM connectors.
•  Inspect for continuity between high pressure fuel pump terminal A (wiring harness-side) and body ground.
•  Is there continuity?
Yes
Refer to the wiring diagram and verify whether or not there is a common connector between high pressure fuel pump terminal A and PCM terminal 1DI.
If there is a common connector:
•  Determine the malfunctioning part by inspecting the common connector and the terminal for corrosion, damage, or pin disconnection, and the common wiring harness for a short to ground.
•  Repair or replace the malfunctioning part.
If there is no common connector:
•  Repair or replace the wiring harness which has a short to ground.
If the malfunction remains:
•  Replace the PCM. (damage to driver in PCM)
No
Replace the high pressure fuel pump.
(See HIGH PRESSURE FUEL PUMP REMOVAL/INSTALLATION [SKYACTIV-G 2.5 (WITH CYLINDER DEACTIVATION)].)
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.
•  Is the low side fuel pressure within specification?
Specification:
•  405—485 kPa {4.13—4.94 kgf/cm2, 58.8—70.3 psi}
Yes
Go to the next step.
No
Inspect the following:
•  Fuel line restriction
•  Fuel filter clogged
―  If there is any malfunction:
•  Repair or replace the malfunctioning part according to the inspection results.
―  If there is no malfunction:
•  Replace the fuel pump unit.
15
INSPECT ENGINE COMPRESSION
•  Measure the compression pressure for each cylinder.
•  Are compression pressures within specification?
Yes
Go to Step 21.
No
Go to the next step.
16
INSPECT ELECTRIC VARIABLE VALVE TIMING DRIVER
•  Inspect the electric variable valve timing driver.
•  Is there any malfunction?
Yes
Replace the electric variable valve timing motor/driver.
(See ELECTRIC VARIABLE VALVE TIMING MOTOR/DRIVER REMOVAL/INSTALLATION [SKYACTIV-G 2.5 (WITH CYLINDER DEACTIVATION)].)
No
Go to the next step.
17
INSPECT ELECTRIC VARIABLE VALVE TIMING MOTOR
•  Inspect the electric variable valve timing motor.
•  Is there any malfunction?
Yes
Replace the electric variable valve timing motor/driver.
(See ELECTRIC VARIABLE VALVE TIMING MOTOR/DRIVER REMOVAL/INSTALLATION [SKYACTIV-G 2.5 (WITH CYLINDER DEACTIVATION)].)
No
Go to the next step.
18
INSPECT ELECTRIC VARIABLE VALVE TIMING ACTUATOR
•  Inspect the electric variable valve timing actuator.
•  Is there any malfunction?
Yes
Replace the electric variable valve timing actuator.
(See ELECTRIC VARIABLE VALVE TIMING ACTUATOR, HYDRAULIC VARIABLE VALVE TIMING ACTUATOR REMOVAL/INSTALLATION [SKYACTIV-G 2.5 (WITH CYLINDER DEACTIVATION)].)
No
Go to the next step.
19
INSPECT HYDRAULIC VARIABLE VALVE TIMING CONTROL SYSTEM OPERATION
•  Perform the Hydraulic Variable Valve Timing Control System Operation Inspection.
•  Is there any malfunction?
Yes
Repair or replace the malfunctioning part according to the inspection results.
No
Go to the next step.
20
INSPECT FOR MALFUNCTION DUE TO DEVIATED VALVE TIMING
•  Inspect the valve timing (timing chain installation condition).
•  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 part according to the inspection results.
No
Adjust the valve timing to the correct timing.
21
INSPECT IGNITION SYSTEM OPERATION
•  Perform the Spark Test.
•  Is a strong blue spark visible at each cylinder?
Yes
Go to the next step.
No
Repair or replace the malfunctioning part according to the inspection results.
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 part according to the inspection results.
No
Go to the next step.
23
INSPECT IF MALFUNCTION CAUSE IS PCV VALVE OR INJECTOR DRIVER (PCM INTEGRATED)
•  Inspect the PCV valve.
•  Is there any malfunction?
Yes
Replace the PCV valve.
(See POSITIVE CRANKCASE VENTILATION (PCV) VALVE REMOVAL/INSTALLATION [SKYACTIV-G 2.5 (WITH CYLINDER DEACTIVATION)].)
No
Injector driver malfunction.
•  Replace the PCM.
If the problem remains, overhaul the engine.
24
Verify the test results.
•  If normal, return to the diagnostic index to service any additional symptoms.
•  If the malfunction remains, inspect the related Service Bulletins and/or On-line Repair Information and perform repair or diagnosis.
―  If the vehicle is repaired, troubleshooting is completed.
―  If the vehicle is not repaired or additional diagnostic information is not available, reprogram the PCM if a later calibration is available. Retest.