NO.7 SLOW RETURN TO IDLE [SKYACTIV-G 2.0]
id0103e6801300
7 |
SLOW RETURN TO IDLE |
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DESCRIPTION
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• Engine takes more time than normal to return to idle speed.
• Engine speed continues at fast idle after warm-up.
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POSSIBLE CAUSE
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• Cooling system malfunction
• PCM DTC is stored
• Erratic signal to PCM
• 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
• Erratic signal from CKP sensor
• Excessive fuel pressure
• Thermostat stuck open
• Throttle body malfunction
• Injector driver (built-into PCM) malfunction
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Diagnostic Procedure
STEP |
INSPECTION |
RESULTS |
ACTION |
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1
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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}?
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Yes
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Perform the symptom troubleshooting “NO.18 COOLING SYSTEM CONCERNS-RUNS COLD”.
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No
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Go to the next step.
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2
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VERIFY PCM DTC
• Retrieve any DTCs using the M-MDS.
• Are any DTCs present?
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Yes
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Go to the applicable DTC inspection.
(See DTC TABLE [SKYACTIV-G 2.0].)
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No
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Go to the next step.
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3
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VERIFY CURRENT INPUT SIGNAL STATUS
• Access the following PIDs using the M-MDS:
• Do the PIDs indicate the correct values under the trouble condition?
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Yes
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Go to the next step.
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No
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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:
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4
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INSPECT COOLING FAN CONTROL SYSTEM OPERATION
• Verify the cooling fan operation.
• Does the cooling fan operate properly according to the ECT PID value?
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Yes
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Go to the next step.
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No
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Perform the Cooling Fan Control System Inspection.
Repair or replace the malfunctioning part according to the inspection results.
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5
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DETERMINE IF MALFUNCTION CAUSE IS DRIVE-BY-WIRE CONTROL SYSTEM OR OTHER
• Will the engine run smoothly at part throttle?
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Yes
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Go to the next step.
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No
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Go to Step 7.
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6
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INSPECT DRIVE-BY-WIRE CONTROL SYSTEM OPERATION
• Perform the TP sweep inspection.
• Does the drive-by-wire control system work properly?
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Yes
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Visually inspect the throttle body (damage/scratching).
• If there is any malfunction:
• If there is no malfunction:
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No
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Repair or replace the malfunctioning part according to the inspection results.
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7
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INSPECT FUEL INJECTOR OPERATION
• Perform the Fuel Injector Operation Inspection.
• Do the fuel injectors operate properly?
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Yes
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Go to the next step.
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No
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Repair or replace the malfunctioning part according to the inspection results.
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8
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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?
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Yes
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Repair or replace the malfunctioning part according to the inspection results.
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No
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Go to the next step.
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9
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INSPECT CKP SENSOR AND CMP SENSOR
• Inspect the CKP sensor, intake CMP sensor and exhaust CMP sensor for the following:
• Is there any malfunction?
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Yes
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Repair or replace the malfunctioning part according to the inspection results.
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No
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Go to the next step.
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10
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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}?
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Yes
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Go to Step 14.
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No
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Lower than 3 MPa {31 kgf/cm2, 435 psi}:
• Inspect the following:
• If there is any malfunction:
• If there is no malfunction:
Higher than 3 MPa {31 kgf/cm2, 435 psi}:
• Go to the next step.
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11
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DETERMINE IF MALFUNCTION CAUSE IS FUEL PRESSURE SENSOR OR HIGH PRESSURE FUEL PUMP
• Is the vehicle acceleration performance normal?
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Yes
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Go to the next step.
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No
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Go to Step 13.
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12
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INSPECT FUEL PRESSURE SENSOR
• Inspect the fuel pressure sensor.
• Is there any malfunction?
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Yes
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Replace the fuel distributor.
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No
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Go to Step 14.
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13
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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?
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Yes
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Repair or replace the wiring harness for a possible short to ground.
• If the malfunction remains:
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No
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Replace the high pressure fuel pump.
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14
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INSPECT THERMOSTAT
• Remove the thermostat.
• Inspect the thermostat operation.
• Is there any malfunction?
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Yes
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Replace the thermostat.
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No
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Inspect the throttle body.
Repair or replace the malfunctioning part according to the inspection results.
• If the throttle body is normal or the problem remains:
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15
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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.
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