NO.9 SLOW RETURN TO IDLE [MZR-CD 2.2]

id0103f3820700

9

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
•  Thermostat is stuck open
•  Fuel injection timing is incorrect
•  Erratic signal from CKP sensor
•  Erratic signal from CMP sensor
•  ECT sensor or related circuit malfunction
•  APP sensor or related circuit malfunction
•  MAF/IAT sensor or related circuit malfunction
•  Incorrect idle speed
•  Excessive fuel pressure
―  Fuel pressure sensor or related circuit malfunction
―  Supply pump malfunction
―  Suction control valve malfunction (built-in supply pump)
―  Fuel pressure limiter malfunction (built-in common rail)
•  Fuel injector malfunction (incorrect fuel regulate pressure)
•  Neutral switch or related circuit 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 [MZR-CD 2.2].) (See AFTER SERVICE PRECAUTION [MZR-CD 2.2].)

Diagnostic Procedure

STEP

INSPECTION

RESULTS

ACTION
1
Retrieve any PCM DTCs using the M-MDS.
(See ON-BOARD DIAGNOSTIC TEST [MZR-CD 2.2].)
Are any DTCs displayed?
Yes
DTC is displayed:
•  Go to the applicable DTC inspection.
Communication error message is displayed:
•  Open circuit in wiring harness between main relay terminal E and PCM terminal 2I
•  Open circuit in wiring harness between main relay terminal C and PCM terminals 2C, 2F
•  Main relay is stuck open.
•  Open or poor ground circuit (PCM terminals 2A, 2B, 2D and 2E)
•  Poor connection of vehicle body ground
No
Go to the next step.
2
Access the ECT PID using the M-MDS.
(See ON-BOARD DIAGNOSTIC TEST [MZR-CD 2.2].)
Start and warm up the engine to normal operating temperature.
Is the ECT PID value between 82—112 °C {180—234 °F}?
Yes
Go to the next step.
No
ECT PID value is higher than 112 °C {234 °F}:
•  Go to the symptom troubleshooting “NO.19 COOLING SYSTEM CONCERNS-OVERHEATING”.
ECT PID value is less than 82 °C {180 °F}:
•  Go to the symptom troubleshooting “NO.20 COOLING SYSTEM CONCERNS-RUNS COLD”.
3
Inspect the idle speed.
(See ENGINE TUNE-UP [MZR-CD 2.2].)
Is there any malfunction?
Yes
Repair or replace the malfunctioning part according to the inspection results.
No
Go to the next step.
4
Perform the coolant heater system inspection.
(See WATER HEATER SYSTEM OPERATION CHECK [FULL-AUTO AIR CONDITIONER].)
(See WATER HEATER SYSTEM OPERATION CHECK [MANUAL AIR CONDITIONER].)
Does the coolant heater system operate properly?
Yes
Go to the next step.
No
Repair or replace the malfunctioning part according to the inspection results.
5
Perform the Cooling Fan Control System Inspection.
(See ENGINE CONTROL SYSTEM OPERATION INSPECTION [MZR-CD 2.2].)
Does the cooling fan control operate properly?
Yes
Go to the next step.
No
Repair or replace the malfunctioning part according to the inspection results.
6
Inspect the APP sensor.
(See ACCELERATOR PEDAL POSITION (APP) SENSOR INSPECTION [MZR-CD 2.2].)
Is there any malfunction?
Yes
Replace the accelerator pedal component.
(See ACCELERATOR PEDAL COMPONENT REMOVAL/INSTALLATION [MZR-CD 2.2].)
No
Go to the next step.
7
Inspect the neutral switch.
(See NEUTRAL SWITCH INSPECTION [MZR-CD 2.2].)
Is there any malfunction?
Yes
Replace the neutral switch.
(See NEUTRAL SWITCH REMOVAL/INSTALLATION [A26M-R].)
No
Go to the next step.
8
Visually inspect the CKP sensor and teeth of pulse wheel.
(See CRANKSHAFT POSITION (CKP) SENSOR INSPECTION [MZR-CD 2.2].)
Are the CKP sensor and teeth of pulse wheel normal?
Yes
Go to the next step.
No
Repair or replace the malfunctioning part according to the inspection results.
9
Visually inspect the CMP sensor and teeth of pulse wheel.
(See CAMSHAFT POSITION (CMP) SENSOR INSPECTION [MZR-CD 2.2].)
Are the CMP sensor and teeth of pulse wheel normal?
Yes
Access the following PIDs using the M-MDS:
(See ON-BOARD DIAGNOSTIC TEST [MZR-CD 2.2].)
(See PCM INSPECTION [MZR-CD 2.2].)
•  ECT
•  IAT
•  MAF
•  RPM
―  If the PID value is not normal:
•  Repair or replace the malfunctioning part according to the inspection results.
―  If the PID value is normal:
•  Go to the next step.
No
Repair or replace the malfunctioning part according to the inspection results.
10
Inspect the suction control valve.
(See SUCTION CONTROL VALVE INSPECTION [MZR-CD 2.2].)
Is there any malfunction?
Yes
Replace the supply pump.
(See SUPPLY PUMP REMOVAL/INSTALLATION [MZR-CD 2.2].)
No
Go to the next step.
11
Remove the thermostat.
(See THERMOSTAT REMOVAL/INSTALLATION [MZR-CD 2.2].)
Inspect the thermostat operation.
(See THERMOSTAT INSPECTION [MZR-CD 2.2].)
Is there any malfunction?
Yes
Replace the thermostat.
(See THERMOSTAT REMOVAL/INSTALLATION [MZR-CD 2.2].)
No
Go to the next step.
12
Inspect the fuel injector relief pressure.
Is there any malfunction?
Yes
Replace the fuel injector.
(See FUEL INJECTOR REMOVAL/INSTALLATION [MZR-CD 2.2].)
No
Remove the supply pump and common rail.
(See SUPPLY PUMP REMOVAL/INSTALLATION [MZR-CD 2.2].)
(See COMMON RAIL REMOVAL/INSTALLATION [MZR-CD 2.2].)
Inspect the supply pump and common rail.
(See SUPPLY PUMP INSPECTION [MZR-CD 2.2].)
(See COMMON RAIL INSPECTION [MZR-CD 2.2].)
Repair or replace the malfunctioning part according to the inspection results.
13
Verify test results.
•  If normal, return to the diagnostic index to service any additional symptoms.
•  If the 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, reprogram the PCM if a later calibration is available. Retest.