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LOW IDLE/STALLS DURING DECELERATION [SKYACTIV-X]

LOW IDLE/STALLS DURING DECELERATION [SKYACTIV-X]

 id0103hf889700

Troubleshooting item

Low idle/stalls during deceleration
Description
•  Engine speed decreases when the accelerator pedal is released.
•  Stalls during deceleration with the accelerator pedal fully released.
•  When the accelerator pedal is fully released, vehicle stalls directly after vehicle stops.
Possible cause
•  PCM DTC is stored
•  Erratic signal to PCM
―  APP sensor or related circuit malfunction
―  Brake switch or related circuit malfunction
―  Clutch stroke sensor or related circuit malfunction (MTX)
―  Communication error between TCM and PCM (ATX)
―  ECT sensor No.1 or related circuit malfunction
―  ECT sensor No.2 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
―  TP sensor or related circuit malfunction
•  Improper operation of A/C magnetic clutch
•  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
•  Fuel leakage
•  Vacuum leakage
•  Engine mount installation loose
•  Erratic signal from CKP sensor
―  Loose installation
―  Damaged trigger wheel (crankshaft pulley)
―  Open or short circuit in related wiring harness
•  Erratic signal from CMP sensor
―  Loose installation
―  Damaged trigger wheel (intake camshaft and/or exhaust camshaft)
―  Open or short circuit in related wiring harness
•  Inadequate fuel pressure (high or low pressure side)
―  High 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 malfunction (built-into high pressure fuel pump)
―  Relief valve (built-into high pressure fuel pump) malfunction
―  Fuel line restriction
―  Fuel filter clogged
―  Fuel pump unit malfunction
•  Low engine compression
•  Improper operation of electric variable valve timing control system
―  Intake electric variable valve timing driver or exhaust electric variable valve timing driver malfunction
―  Intake electric variable valve timing motor or exhaust electric variable valve timing motor malfunction
―  Intake electric variable valve timing actuator or exhaust electric variable valve timing actuator malfunction
•  ATX malfunction (ATX)
•  Integrated starter generator (ISG) malfunction (part, system, control malfunction)
―  Amount of integrated starter generator (ISG) voltage is large
•  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.
―  Highly pressurized fuel may spray out if the fuel line is cut. Due to the following dangers occurring with a fuel spray, always complete the “Fuel Line Safety Procedure” to prevent the fuel from spraying.
•  Fuel may cause irritation if it comes in contact with skin and eyes.
•  If fuel ignites and causes a fire, it may lead to serious injury or death, and damage to property and facilities.
―  Fuel is highly flammable and dangerous. Fuel line spills and leakage can cause serious injury or death, and damage to equipment. Always refer to the “Quick Release Connector Removal/Installation (fuel system)” before performing the fuel hose installation, and execute the “Fuel Leakage Inspection” after installation.
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 material.

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

Related PIDs

PIDs

Reference
A/C_REQ
(See PID/DATA MONITOR TABLE [PCM (SKYACTIV-X)].)
ALT_VOLT_OUT_ACT
APP1
APP2
CLTCH_PEDAL_POS
ECT
ECT_VOLT
ECT2
ECT2_VOLT
FUEL_PRES
LOAD_CALC
LONG_FUEL_TRIM
MAF
MAP
MAP_VOLT
A/F_SEN_CUR
HO2S_OUT_VOLT
ENG_RPM
SHRT_FUEL_TRIM
TP_RELAT
VSS
BRK_SW
(See PID/DATA MONITOR TABLE [ELECTRICAL SUPPLY UNIT (ESU) (E)].)

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 [SKYACTIV-X].)
(See CRANKS NORMALLY BUT WILL NOT START [SKYACTIV-X].)
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 [SKYACTIV-X].)
No
Go to the next step.
3
VERIFY PCM DTC
•  Perform the DTC inspection for the PCM.
•  Are any DTCs displayed?
Yes
Repair the malfunctioning location according to the applicable DTC troubleshooting.
(See DTC TABLE [PCM (SKYACTIV-X)].)
No
Go to the next step.
4
VERIFY CURRENT INPUT SIGNAL STATUS
Warning
•  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:
PCM:
―  APP1
―  APP2
―  CLTCH_PEDAL_POS (MTX)
―  ECT
―  ECT_VOLT
―  ECT2
―  ECT2_VOLT
―  MAF
―  MAP
―  MAP_VOLT
―  TP_RELAT
―  A/F_SEN_CUR
―  HO2S_OUT_VOLT
―  SHRT_FUEL_TRIM
―  LONG_FUEL_TRIM
Electrical supply unit (ESU):
―  BRK_SW
•  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 No.1 and No.2.
CLTCH_PEDAL_POS PID is not as specified: (MTX)
•  Inspect the clutch stroke sensor.
ECT, ECT_VOLT, ECT2, ECT2_VOLT PIDs are not as specified:
•  Inspect the ECT sensor No.1 and No.2.
MAF PID is not as specified:
•  Inspect the MAF sensor.
MAP, MAP_VOLT PIDs are not as specified:
•  Inspect the MAP sensor.
TP_RELAT PID is not as specified:
•  Inspect the TP sensor.
A/F_SEN_CUR, SHRT_FUEL_TRIM, LONG_FUEL_TRIM PIDs are not as specified:
•  Inspect the A/F sensor.
HO2S_OUT_VOLT PID is not as specified:
•  Inspect the HO2S.
BRK_SW PID is not as specified:
•  Inspect the brake switch.
Repair or replace the malfunctioning location.
•  If the malfunction remains:
―  Inspect communication error between TCM and PCM. (ATX)
•  Repair or replace the malfunctioning location and perform the repair completion verification.
―  Perform the “Action for Non-repeatable Malfunction” procedure.
5
DETERMINE IF MALFUNCTION CAUSE IS A/C REQUEST SIGNAL OR OTHER
•  Access the PCM PID A/C_REQ 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 on to off according to switch control panel?
Yes
Go to the next step.
No
If the A/C_REQ PID is always ON:
•  Perform the symptom troubleshooting “A/C IS ALWAYS ON OR A/C COMPRESSOR RUNS CONTINUOUSLY”.
If the A/C_REQ PID is always OFF:
•  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.
No
Go to the next step.
7
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 location and perform the repair completion verification.
•  If there is no malfunction:
―  Go to the next step.
No
Repair or replace the malfunctioning location and perform the repair completion verification.
8
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 location and perform the repair completion verification.
9
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 location and perform the repair completion verification.
10
INSPECT RELATED PART CONDITION
•  Inspect the following:
―  Fuel quality (proper octane, contamination, winter/summer blend)
―  Intake-air system restriction or leakage
―  Fuel leakage in fuel system
―  Vacuum leakage
―  Engine mount loose
―  CKP sensor, intake CMP sensor and exhaust CMP sensor
•  Installation condition
•  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.
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.
•  Is the FUEL_PRES PID value within specification?
Specification:
•  Approx. 40—60 MPa {408—611 kgf/cm2, 5,802—8,702 psi}
Yes
Go to Step 15.
No
FUEL_PRES PID value is lower than 40 MPa {408 kgf/cm2, 5,802 psi}:
•  Inspect the following:
―  Fuel leakage at the fuel line and fuel injector
―  Fuel pump
•  Perform the Fuel Pump (Low-pressure Side) Operation Inspection.
―  High fuel pressure sensor
―  High pressure fuel pump
•  If there is any malfunction:
―  Repair or replace the malfunctioning location and perform the repair completion verification.
•  If there is no malfunction:
―  Go to Step 14.
FUEL_PRES PID value is higher than 60 MPa {611 kgf/cm2, 8,702 psi}:
•  Go to the next step.
12
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.
No
Go to Step 14.
13
INSPECT HIGH FUEL PRESSURE SENSOR FOR MALFUNCTION
•  Inspect the applicable part.
•  Is the part normal?
Yes
Go to Step 15.
No
Replace the fuel distributor and perform the repair completion verification.
(See FUEL DISTRIBUTOR REMOVAL/INSTALLATION [SKYACTIV-X 2.0].)
14
INSPECT SPILL VALVE CONTROL SOLENOID VALVE CONTROL CIRCUIT FOR SHORT TO GROUND
•  Inspect the applicable circuit for a short to ground.
•  Is the circuit normal?
Yes
Replace the high pressure fuel pump and perform the repair completion verification.
(See HIGH PRESSURE FUEL PUMP REMOVAL/INSTALLATION [SKYACTIV-X 2.0].)
No
Repair or replace the malfunctioning location and perform the repair completion verification.
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.
•  Is the low side fuel pressure within specification?
Specification:
•  545—695 kPa {5.56—7.08 kgf/cm2, 79.1—100.0 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 location and perform the repair completion verification.
―  If there is no malfunction:
•  Replace the fuel pump unit and perform the repair completion verification.
16
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.
17
INSPECT INTAKE ELECTRIC VARIABLE VALVE TIMING DRIVER OR EXHAUST ELECTRIC VARIABLE VALVE TIMING DRIVER FOR MALFUNCTION
•  Inspect the applicable part.
•  Is the part normal?
Yes
Go to the next step.
No
Repair or replace the malfunctioning location and perform the repair completion verification.
(See ELECTRIC VARIABLE VALVE TIMING MOTOR/DRIVER REMOVAL/INSTALLATION [SKYACTIV-X 2.0].)
18
INSPECT INTAKE ELECTRIC VARIABLE VALVE TIMING MOTOR OR EXHAUST ELECTRIC VARIABLE VALVE TIMING MOTOR FOR MALFUNCTION
•  Inspect the applicable part.
•  Is the part normal?
Yes
Go to the next step.
No
Repair or replace the malfunctioning location and perform the repair completion verification.
(See ELECTRIC VARIABLE VALVE TIMING MOTOR/DRIVER REMOVAL/INSTALLATION [SKYACTIV-X 2.0].)
19
INSPECT INTAKE ELECTRIC VARIABLE VALVE TIMING ACTUATOR OR EXHAUST ELECTRIC VARIABLE VALVE TIMING ACTUATOR FOR MALFUNCTION
•  Inspect the applicable part.
•  Is the part normal?
Yes
Go to the next step.
No
Repair or replace the malfunctioning location and perform the repair completion verification.
(See ELECTRIC VARIABLE VALVE TIMING ACTUATOR REMOVAL/INSTALLATION [SKYACTIV-X 2.0].)
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 location and perform the repair completion verification.
No
Adjust the valve timing to the correct timing and perform the repair completion verification.
21
INSPECT ENGINE MOUNT FOR LOOSENESS
•  Inspect the engine mount for looseness.
•  Is the engine mount normal?
Yes
ATX:
•  Go to the next step.
MTX:
•  Go to Step 24.
No
Repair or replace the malfunctioning location and perform the repair completion verification.
22
VERIFY TCM DTC
•  Perform the DTC inspection for the TCM.
•  Are any DTCs displayed?
Yes
Repair the malfunctioning location according to the applicable DTC troubleshooting.
(See ON-BOARD DIAGNOSTIC SYSTEM DTC TABLE [TCM (ET6A-EL, ET6AX-EL) (E)].)
No
Go to the next step.
23
VERIFY INTEGRATED STARTER GENERATOR (ISG) DTCs
•  Perform the DTC inspection for the integrated starter generator (ISG).
•  Are any DTCs displayed?
Yes
Repair the malfunctioning location according to the applicable DTC troubleshooting.
(See DTC TABLE [INTEGRATED STARTER GENERATOR (ISG)].)
No
Injector driver malfunction.
•  Replace the PCM.
If the problem remains, overhaul the engine and perform the repair completion verification.
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)
No
Refer to the controller area network (CAN) malfunction diagnosis flow to inspect for a CAN communication error.
(See CONTROLLER AREA NETWORK (CAN) MALFUNCTION DIAGNOSIS FLOW [(E)].)
•  If the CAN communication is normal, perform the diagnosis from Step 1.
―  If the malfunction recurs, go to the next step.
Repair completion verification 2
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?
Yes
Perform the PCM reprogramming and verify if the malfunction symptom was corrected.
•  If the malfunction recurs, replace the PCM.
No
Replace the PCM.
(See PCM REMOVAL/INSTALLATION [SKYACTIV-X 2.0].)