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NO.7 SLOW RETURN TO IDLE

BHE010300103W09

7 | SLOW RETURN TO IDLE
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DESCRIPTION | The engine takes more time than normal to return to idle speed.
POSSIBLE CAUSE | • ECT sensor malfunction • The thermostat is stuck open. • Throttle body malfunction • Air leakage from intake-air system • Eccentric shaft bypass valve stuck open

Diagnostic procedure

STEP | INSPECTION | RESULTS | ACTION
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1 | Connect the WDS or equivalent to the DLC-2. Retrieve any continuous memory, KOEO and KOER DTCs. Are there any DTCs displayed? | Yes | DTC is displayed: Go to the applicable DTC inspection. (See DTC TABLE.)
No | No DTC is displayed: Go to the next step.
2 | Remove the thermostat and inspect the operation. (See THERMOSTAT REMOVAL/INSTALLATION.) (See THERMOSTAT INSPECTION.) Is the thermostat normal? | Yes | The ECT and the thermostat are normal. Go to the next step.
No | Access the ECT PID on the WDS or equivalent. Inspect the readings on both the ECT PID and the temperature gauge on the instrument cluster. If the temperature gauge on the instrument cluster indicates the normal range but the ECT PID is not the same as the temperature gauge reading, inspect the ECT sensor. (See ENGINE COOLANT TEMPERATURE (ECT) SENSOR INSPECTION.) If the temperature gauge on the instrument cluster indicates the cold range but the ECT PID is normal, inspect the temperature gauge and the sending unit. (See Water temperature gauge.)
3 | Is the throttle body free of contamination? | Yes | Go to the next step.
No | Clean or replace throttle body.
4 | Inspect for air leakage from the intake-air system components while racing the engine to a higher speed. Is there air leakage from the intake-air system? | Yes | Repair or replace the malfunctioning parts according to the inspection results.
No | Inspect the eccentric shaft bypass valve. (See Engine Workshop Manual.)
5 | 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.