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NO.7 SLOW RETURN TO IDLE [L3 Turbo]

id0103b4801300

7 | SLOW RETURN TO IDLE
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DESCRIPTION | • Engine takes more time than normal to return to idle speed. • Engine speed continues at fast idle after warm-up
POSSIBLE CAUSE | • ECT sensor or related circuit malfunction • Thermostat is stuck open • Fuel injection timing is incorrect • Erratic signal from CKP sensor • Erratic signal from CMP sensor • Accelerator position sensor or related circuit malfunction • Air suction in intake-air system • MAF sensor or related circuit malfunction • Fuel pressure sensor or related circuit malfunction • Excessive fuel pressure • Relief valve malfunction (built-in delivery pipe) • Fuel injector malfunction • Cooling fan control system malfunction • Improper load signal input • Injector driver module 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 ROCEDURE" and "AFTER REPAIR PROCEDURE" described in this manual. (See BEFORE SERVICE PRECAUTION [L3 Turbo].) (See AFTER SERVICE PRECAUTION [L3 Turbo].) Caution • Disconnecting/connecting the quick release connector without cleaning it may possibly cause damage to the fuel pipe and quick release connector. Always clean the quick release connector joint area before disconnecting/connecting, and make sure that it is free of foreign material.

Diagnostic procedure

STEP | INSPECTION | RESULTS | ACTION
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1 | Inspect air suction in intake-air system components while racing engine to higher speed. Is any air suction? | Yes | Repair or replace as necessary.
No | Go to the next step.
2 | Perform the self-test function using the WDS or equivalent. Turn the ignition switch to the ON position. Retrieve any DTCs. Is a DTC displayed? | Yes | DTC is displayed: Go to the appropriate DTC test.
No | No DTC is displayed: Go to the next step.
3 | Access the ECT PID. Start and warm-up engine to normal operating temperature. Is the ECT PID reading below 82°C {180°F}? | Yes | Go to the next step.
No | Go to symptom troubleshooting "NO.18 COOLING SYSTEM CONCERNS, RUNS COLD". (See NO.18 COOLING SYSTEM CONCERNS-RUNS COLD [L3 Turbo].)
4 | Verify the cooling fan operation. Does the cooling fan operate properly according ECT PID value? | Yes | Go to the next step.
No | Perform the Cooling Fan Control System Operation Inspection. (See Cooling Fan Control System Inspection.)
5 | Inspect CMP and CKP sensor for the following; • Installation condition (See CAMSHAFT POSITION (CMP) SENSOR REMOVAL/INSTALLATION [L3 Turbo].) (See CRANKSHAFT POSITION (CKP) SENSOR REMOVAL/INSTALLATION [L3 Turbo].) • Damaged trigger wheel and camshaft • Open or short circuit in the wiring harnesses. Is there any malfunction detected? | Yes | Repair or replace the malfunctioning part according inspection results.
No | Go to the next step.
6 | Access and monitor following the PIDs using the data monitor function. • ECT • APP • MAF • CPP (PCM terminal 1H) • PNP (PCM terminal 1W) • PSP (PCM terminal 1Z) Do the PIDs indicate the correct values under trouble condition? (See Using the WDS or Equivalent.) | Yes | Go to the next step.
No | Inspect and repair or replace suspected parts and the related harnesses. If the malfunction remains, perform the intermittent concern troubleshooting procedure. (See INTERMITTENT CONCERN TROUBLESHOOTING [L3 Turbo].)
7 | Access and monitor the FUEL_PRES PID. Is the FUEL_PRES PID value within the specification? (See Using the WDS or Equivalent.) | Yes | Go to Step 11.
No | Go to the next step.
8 | Is the vehicle accelerate performance normally? | Yes | Go to the next step.
No | Go to Step 10.
9 | Inspect the fuel pressure sensor. (See FUEL PRESSURE SENSOR INSPECTION [L3 Turbo].) Is the fuel pressure sensor normal? | Yes | Go to Step 11.
No | Replace the delivery pipe.
10 | Replace the high pressure fuel pump. Monitor FUEL_PRES PID. Is the FUEL_PRES PID value within the specified? (See Using the WDS or Equivalent.) | Yes | Troubleshooting is completed. Go to Step 13.
No | Go to the next step.
11 | Inspect the fuel injector for each cylinder. (See FUEL INJECTOR INSPECTION [L3 Turbo].) Are fuel injectors normal? | Yes | Go to the next step.
No | Replace the suspected fuel injector. (See FUEL INJECTOR REMOVAL/INSTALLATION [L3 Turbo].)
12 | Remove the thermostat and inspection operation. (See THERMOSTAT REMOVAL/INSTALLATION [L8, LF, L3, L3 Turbo].) (See THERMOSTAT INSPECTION [L8, LF, L3, L3 Turbo].) Is the thermostat normal? | Yes | Inspect and repair or replace the throttle body. If throttle body is normal or the problem remains, replace the injector driver module.
No | Replace thermostat.
13 | Verify test results. • If normal, return to the diagnostic index to service any additional symptoms. • If a malfunction remains, inspect the related Service Bulletins and/or On-line Repair 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.