NO.7 SLOW RETURN TO IDLE [SKYACTIV-G 2.0]

id0103e6801300

7

SLOW RETURN TO IDLE
DESCRIPTION
•  Engine takes more time than normal to return to idle speed.
•  Engine speed continues at fast idle after warm-up.
POSSIBLE CAUSE
•  Cooling system malfunction
•  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
―  A/F sensor or related circuit malfunction
―  HO2S or related circuit malfunction
―  Improper air/fuel mixture ratio control operation
•  Cooling fan control system malfunction
•  Improper operation of drive-by-wire control system
•  Incorrect fuel injection timing
•  Fuel injector malfunction
•  Air suction in intake-air system
•  Erratic 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
•  Excessive fuel pressure
―  Fuel pressure sensor or related circuit malfunction
―  High pressure fuel pump malfunction
―  Relief valve (built-into 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
•  Thermostat stuck open
•  Throttle body malfunction
•  Injector driver (built-into PCM) malfunction
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 2.0].) (See AFTER SERVICE PRECAUTION [SKYACTIV-G 2.0].)
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.

Diagnostic Procedure

STEP

INSPECTION

RESULTS

ACTION
1
VERIFY IF MALFUNCTION CAUSE IS RUNS COLD
•  Access the ECT PID using the M-MDS.
•  Start the engine and warm it up completely.
•  Is the ECT PID value below 82 °C {180 °F}?
Yes
Perform the symptom troubleshooting “NO.18 COOLING SYSTEM CONCERNS-RUNS COLD”.
(See NO.18 COOLING SYSTEM CONCERNS-RUNS COLD [SKYACTIV-G 2.0].)
No
Go to the next step.
2
VERIFY PCM DTC
•  Retrieve any DTCs using the M-MDS.
•  Are any DTCs present?
Yes
Go to the applicable DTC inspection.
(See DTC TABLE [SKYACTIV-G 2.0].)
No
Go to the next step.
3
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
―  O2S11
―  O2S12
―  SHRTFT1
―  LONGFT1
•  Do the PIDs indicate the correct values under the trouble 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.
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.
4
INSPECT COOLING FAN CONTROL SYSTEM OPERATION
•  Verify the cooling fan operation.
•  Does the cooling fan operate properly according to the ECT PID value?
Yes
Go to the next step.
No
Perform the Cooling Fan Control System Inspection.
(See ENGINE CONTROL SYSTEM OPERATION INSPECTION [SKYACTIV-G 2.0].)
Repair or replace the malfunctioning part according to the inspection results.
5
DETERMINE IF MALFUNCTION CAUSE IS DRIVE-BY-WIRE CONTROL SYSTEM OR OTHER
•  Will the engine run smoothly at part throttle?
Yes
Go to the next step.
No
Go to Step 7.
6
INSPECT DRIVE-BY-WIRE CONTROL SYSTEM OPERATION
•  Perform the TP sweep 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 INTAKE-AIR SYSTEM FOR AIR SUCTION
•  Inspect for air suction in the intake-air system components while racing the engine to higher speed.
•  Is there any air suction?
Yes
Repair or replace the malfunctioning part according to the inspection results.
No
Go to the next step.
9
INSPECT CKP SENSOR AND CMP SENSOR
•  Inspect the CKP sensor, intake CMP sensor and exhaust CMP sensor for the following:
―  Installation condition
―  Damaged trigger wheel, intake camshaft and exhaust camshaft
•  Is there any malfunction?
Yes
Repair or replace the malfunctioning part according to the inspection results.
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. 3 MPa {31 kgf/cm2, 435 psi}?
Yes
Go to Step 14.
No
Lower than 3 MPa {31 kgf/cm2, 435 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 3 MPa {31 kgf/cm2, 435 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 2.0].)
No
Go to Step 14.
13
INSPECT SPILL VALVE CONTROL SOLENOID VALVE CONTROL CIRCUIT FOR SHORT TO GROUND
•  Switch the ignition to 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
Repair or replace the wiring harness for a possible 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 2.0].)
14
INSPECT THERMOSTAT
•  Remove the thermostat.
•  Inspect the thermostat operation.
•  Is there any malfunction?
Yes
Replace the thermostat.
(See THERMOSTAT REMOVAL/INSTALLATION [SKYACTIV-G 2.0].)
No
Inspect the throttle body.
(See THROTTLE BODY INSPECTION [SKYACTIV-G 2.0].)
Repair or replace the malfunctioning part according to the inspection results.
•  If the throttle body is normal or the problem remains:
―  Replace the PCM (injector driver malfunction).
15
Verify the test results.
•  If normal, return to the diagnostic index to service any additional symptoms.
•  If a malfunction remains, inspect the related Service Information and perform the repair or diagnosis.
―  If the vehicle is repaired, troubleshooting is completed.
―  If the vehicle is not repaired or additional diagnostic information is not available, replace the PCM.