NO.7 SLOW RETURN TO IDLE [MZR 2.0, MZR 2.5]


id0103e1801300

7

SLOW RETURN TO IDLE

DESCRIPTION
•  The engine takes more time than normal to return to idle speed.
POSSIBLE CAUSE
•  ECT sensor malfunction
•  Thermostat is stuck open
•  Throttle body malfunction
•  Air leakage from intake air system
•  PCM malfunction

Diagnostic procedure

STEP

INSPECTION

RESULTS

ACTION

1
Connect the M-MDS to the DLC-2.
Switch the ignition to ON (engine off).
Retrieve any DTCs.
Are any DTCs present?
Yes
Go to the appropriate DTC inspection.
No
Go to the next step.
2
Access the ECT PID using the M-MDS.
Start the engine and warm it up to ECT PID is above 90 °C {194 °F}.
Does the ECT PID increasing dull at thermostat initial opening temperature?
Thermostat initial opening temperature
•  80—84 °C {176—183 °F}
Yes
Go to Step 4.
No
Go to the next step.
3
Remove the thermostat.
Inspect the thermostat operation.
Is there any malfunction?
Yes
Replace the thermostat.
No
Inspect the characteristic of the ECT sensor.
Replace the ECT sensor, if necessary.
4
Is the throttle body free of contamination?
Yes
Inspect for air leakage from the intake air system components while racing the engine to higher speed.
Repair or replace the malfunctioning part according to the inspection results.
No
Clean or replace the throttle body.
5
•  Verify the test results.
―  If normal, return to diagnostic index to service any additional symptoms. (See SYMPTOM DIAGNOSTIC INDEX [MZR 2.0, MZR 2.5].)
―  If a malfunction remains, inspect the related Service Information and perform 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. (See PCM REMOVAL/INSTALLATION [MZR 2.0, MZR 2.5].)