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NO.7 SLOW RETURN TO IDLE [MZR-CD (RF Turbo)]

BME010300000W42

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 | • 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
• Accelerator position sensor or related circuit malfunction
• MAF/IAT sensor or related circuit malfunction
• Fuel pressure sensor or related circuit malfunction
• Incorrect adjustment accelerator pedal position sensor and/or idle switch
• Incorrect adjustment of idle speed
• Excessive fuel pressure
• Fuel pressure limiter malfunction (built-in common rail)
• Fuel injector malfunction (incorrect fuel regulate pressure)
• Main fan control system malfunction
• Neutral switch or related circuit malfunction
• IDM 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 REPAIR PROCEDURE" and "AFTER REPAIR PROCEDURE" described in this manual.

Diagnostic Procedure

STEP | INSPECTION | RESULTS | ACTION
--- | --- | --- | ---
1 | Connect WDS or equivalent to DLC-2. Turn engine switch to ON. Retrieve any DTC. Is DTC displayed? | Yes | DTC is displayed: Go to appropriate DTC test. Communication error message is displayed: Inspect for following: • Open circuit between PCM control relay and PCM terminal 53 or 79
• Open circuit PCM control relay and PCM terminal 69
• PCM control relay stuck open
• Open or poor GND circuit (PCM terminal 65, 85, 103 or 104)
• Poor connection vehicle body GND
No | No DTC is displayed: Go to next step.
2 | Access ECT PID. Start and warm-up engine to normal operating temperature. Is ECT PID reading between 82-112 °C {180-233 °F}? | Yes | Go to next step.
No | ECT PID is higher than 112 °C {233 °F}: Go to symptom troubleshooting "NO.17 COOLING SYSTEM CONCERNS-OVERHEATING". ECT PID is less than 82 °C {180 °F}: Go to symptom troubleshooting "NO.18 COOLING SYSTEM CONCERNS-RUNS COLD".
3 | Inspect idle speed. (See IDLE SPEED INSPECTION [MZR-CD (RF Turbo)].) Is idle speed correct? | Yes | Go to next step.
No | Repair or replace malfunctioning part according to idle speed inspection results.
4 | Inspect main fan control system operation. Does main fan control operate properly? | Yes | Go to next step.
No | Repair or replace malfunctioning part according to main fan control system operation inspection results.
5 | Inspect adjustment of accelerator position sensor and idle switch. (See ACCELERATOR POSITION SENSOR INSPECTION [MZR-CD (RF Turbo)].) (See IDLE SWITCH INSPECTION [MZR-CD (RF Turbo)].) Are accelerator position sensor and idle switch adjusted correctly? | Yes | Go to next step.
No | Adjust accelerator position sensor and idle switch correctly. (See ACCELERATOR POSITION SENSOR ADJUSTMENT [MZR-CD (RF Turbo)].) (See IDLE SWITCH ADJUSTMENT [MZR-CD (RF Turbo)].)
6 | Inspect adjustment of neutral switch. (See NEUTRAL SWITCH INSPECTION [MZR-CD (RF Turbo)].) Is neutral switch adjusted correctly? | Yes | Go to next step.
No | Adjust neutral switch correctly.
7 | Visually inspect CKP sensor and teeth of pulse wheel. Are CKP sensor and teeth of pulse wheel okay? | Yes | Go to next step.
No | Replace malfunctioning parts.
8 | Measure gap between CKP sensor and teeth of pulse wheel. Specification 1.5-2.5 mm {0.059-0.098 in} Is gap within specification? | Yes | Go to next step.
No | Adjust CKP sensor position.
9 | Visually inspect CMP sensor and teeth of pulse wheel. Are CMP sensor and teeth of pulse wheel okay? | Yes | Inspect following PIDs: (See PCM INSPECTION [MZR-CD (RF Turbo)].) • ECT • IAT • MAF
• RPM
If PID value is not as specified, repair or replace malfunctioning parts.
If PID value is okay, go to next step.
No | Replace malfunctioning parts.
10 | Remove thermostat and inspect operation. (See THERMOSTAT REMOVAL/INSTALLATION [MZR-CD (RF Turbo)].) (See THERMOSTAT INSPECTION.) Is thermostat okay? | Yes | Go to next step.
No | Replace thermostat.
11 | Inspect fuel injector relief pressure. Is fuel injector relief pressure okay? | Yes | Remove and inspect supply pump and common rail.
No | Replace fuel injector.
12 | Verify test results. • If okay, return to diagnostic index to service any additional symptoms. • If malfunction remains, replace PCM. (See PCM REMOVAL/INSTALLATION [MZR-CD (RF Turbo)].)