NO.7 SLOW RETURN TO IDLE [WL-C, WE-C]

id0103b6801300

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 pedal position (APP) sensor or related circuit malfunction
•  MAF sensor/IAT sensor No.2 or related circuit malfunction
•  Fuel pressure sensor or related circuit malfunction
•  Incorrect idle speed
•  Excessive fuel pressure
•  Supply pump malfunction
•  Fuel pressure limiter malfunction (built-in common rail)
•  Fuel injector malfunction (incorrect fuel regulate pressure)
•  A/C system 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 the M-MDS to the DLC-2.
Turn the engine switch to the ON position (Engine off).
Retrieve any DTCs.
Are any DTCs displayed?
Yes
DTC is displayed:
Go to the appropriate DTC test.
(See DTC TABLE [WL-C, WE-C (Thailand, General (L.H.D. R.H.D.) specs.)].)
Communication error message is displayed:
Inspect the following:
•  Open circuit between main relay and PCM terminal 201, 203, 205
•  Open circuit main relay and PCM terminal 219
•  Main relay stuck open
•  Open or poor ground circuit (PCM terminal 202, 204, 206)
•  Poor connection to vehicle body ground
No
No DTC is displayed:
Go to the next step.
2
Access ECT PID.
Start and warm-up the engine to normal operating temperature.
Is the ECT PID reading between 82—112 °C {180—233 °F}?
Yes
Go to the next step.
No
ECT PID is higher than 112 °C {233 °F}:
Go to the symptom troubleshooting “NO.17 COOLING SYSTEM CONCERNS-OVERHEATING [WL-C, WE-C]”.
ECT PID is less than 82 °C {180 °F}:
Go to the symptom troubleshooting “NO.18 COOLING SYSTEM CONCERNS-RUNS COLD [WL-C, WE-C]”.
3
Inspect the idle speed.
(See ENGINE TUNE-UP [WL-C, WE-C].)
Is the idle speed correct?
Yes
Go to the next step.
No
Repair or replace malfunctioning part according to idle speed inspection results.
4
Inspect the A/C system operation
•  Are A/C operation normal ?
Yes
Go to the next step.
No
Go to the symptom trouble shooting “No.23 A/C DOES NOT WORK SUFFICIENTLY [WL-C, WE-C]” and “No.24 A/C ALWAYS ON OR A/C COMPRESSOR RUNS CONTINUOUSLY [WL-C, WE-C]”.
5
Inspect the cooling fan control system operation.
Does the cooling fan control operate properly?
Yes
Go to the next step.
No
Repair or replace the malfunctioning part according to cooling fan No.2 control system operation inspection results.
6
Inspect the APP sensor.
(See ACCELERATOR PEDAL POSITION (APP) SENSOR INSPECTION [WL-C, WE-C].)
Is the APP sensor normal?
Yes
Go to the next step.
No
Replace the accelerator pedal component.
7
Inspect the CKP sensor.
(See CRANKSHAFT POSITION (CKP) SENSOR INSPECTION [WL-C, WE-C].)
(See CRANKSHAFT POSITION (CKP) SENSOR REMOVAL/INSTALLATION [WL-C, WE-C].)
Is the CKP sensor normal?
Yes
Go to the next step.
No
Replace the CKP sensor.
Then go to the next step.
8
Visually inspect the CMP sensor and the teeth of the pulse wheel.
Are the CMP sensor and the teeth of the pulse wheel normal?
Yes
Inspect the following PIDs:
(See PCM INSPECTION (Thailand, General (L.H.D. R.H.D.) specs.) [WL-C, WE-C].)
•  ECT
•  IAT
•  MAF
•  RPM
If the PID value is not as specified, repair or replace malfunctioning parts.
If the PID value is normal, go to the next step.
No
Replace malfunctioning parts.
9
Remove the thermostat and inspect the operation.
(See THERMOSTAT REMOVAL/INSTALLATION [WL-C, WE-C].)
(See THERMOSTAT INSPECTION [WL-C, WE-C].)
Is the thermostat normal?
Yes
Go to the next step.
No
Replace thermostat.
10
Inspect the fuel injector relief pressure.
Is the fuel injector relief pressure normal?
Yes
Remove and inspect the supply pump and the common rail.
No
Replace the fuel injector.
(See FUEL INJECTOR REMOVAL/INSTALLATION [WL-C, WE-C].)
11
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 repair or diagnosis.
―  If the vehicle is repaired, troubleshooting completed.
―  If the vehicle is not repaired or additional diagnostic information is not available, reprogram the PCM if later calibration is available. Retest.