NO.7 SLOW RETURN TO IDLE [MZR 2.3 DISI Turbo]

id0103e2801300

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
•  ECT sensor or related circuit malfunction
•  Thermostat is stuck open
•  Incorrect fuel injection timing
•  Erratic signal from CKP sensor
•  Erratic signal from CMP sensor
•  APP sensor or related circuit malfunction
•  Air suction in intake-air system
•  MAF sensor (integrated in MAF/IAT sensor) or related circuit malfunction
•  Fuel pressure sensor (built-in fuel delivery pipe) or related circuit malfunction
•  Excessive fuel pressure
•  Relief valve malfunction (built-in fuel delivery pipe)
•  Fuel injector malfunction
•  Cooling fan control system malfunction
•  Improper load signal input
•  Injector driver circuit (built-in PCM) 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 SERVICE PRECAUTION” and “AFTER SERVICE PRECAUTION” described in this manual. (See BEFORE SERVICE PRECAUTION [MZR 2.3 DISI Turbo].) (See AFTER SERVICE PRECAUTION [MZR 2.3 DISI 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
1
Inspect the air suction in the intake-air system components while racing the engine to higher speed.
Is there any air suction?
Yes
Repair or replace the malfunctioning part according to the inspection results.
No
Go to the next step.
2
Switch the ignition to ON.
Retrieve any DTCs using the M-MDS.
(See ON-BOARD DIAGNOSTIC TEST [MZR 2.3 DISI Turbo].)
Are any DTCs present?
Yes
Go to the applicable DTC inspection.
(See DTC TABLE [MZR 2.3 DISI Turbo].)
No
Go to the next step.
3
Access the ECT PID using the M-MDS.
(See ON-BOARD DIAGNOSTIC TEST [MZR 2.3 DISI Turbo].)
Start the engine and warm it up completely.
Is the ECT PID value below 82 °C {180 °F}?
Yes
Go to the next step.
No
Perform the symptom troubleshooting “NO.18 COOLING SYSTEM CONCERNS-RUNS COLD”.
(See NO.18 COOLING SYSTEM CONCERNS-RUNS COLD [MZR 2.3 DISI Turbo].)
4
Verify the cooling fan operation.
Does the cooling fan operate properly according to the ECT PID value?
Yes
Go to the next step.
No
Perform the Cooling Fan Control System Inspection.
(See ENGINE CONTROL SYSTEM OPERATION INSPECTION [MZR 2.3 DISI Turbo].)
Repair or replace the malfunctioning part according to the inspection results.
5
Inspect the CMP sensor and CKP sensor for the following:
•  Installation condition
•  Damaged trigger wheel and camshaft
•  Open or short circuit in the wiring harnesses
Is there any malfunction?
Yes
Repair or replace the malfunctioning parts according to the inspection results.
No
Go to the next step.
6
Access the following PIDs using the M-MDS:
(See ON-BOARD DIAGNOSTIC TEST [MZR 2.3 DISI Turbo].)
•  ECT
•  APP1
•  APP2
•  MAF
Do the PID values indicate the correct values under the trouble condition?
(See PCM INSPECTION [MZR 2.3 DISI Turbo].)
Yes
Go to the next step.
No
Inspect the suspected parts and related wiring harness.
•  If normal:
―  Perform the “INTERMITTENT CONCERN TROUBLESHOOTING.
•  If not:
―  Repair or replace the malfunctioning parts according to the inspection results.
7
Access the FUEL_PRES PID using the M-MDS.
(See ON-BOARD DIAGNOSTIC TEST [MZR 2.3 DISI Turbo].)
Is the FUEL_PRES PID value within the specification?
(See PCM INSPECTION [MZR 2.3 DISI Turbo].)
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 [MZR 2.3 DISI Turbo].)
Is there any malfunction?
Yes
Replace the fuel delivery pipe.
(See FUEL INJECTOR REMOVAL/INSTALLATION [MZR 2.3 DISI Turbo].)
No
Go to Step 11.
10
Replace the high pressure fuel pump.
(See HIGH PRESSURE FUEL PUMP REMOVAL/INSTALLATION [MZR 2.3 DISI Turbo].)
Access the FUEL_PRES PID using the M-MDS.
(See ON-BOARD DIAGNOSTIC TEST [MZR 2.3 DISI Turbo].)
Is the FUEL_PRES PID value within the specified?
(See PCM INSPECTION [MZR 2.3 DISI Turbo].)
Yes
High-pressure fuel pump or spill valve control solenoid valve (built-in high pressure fuel pump or fuel pressure sensor) malfunction.
•  Go to Step 13.
No
Relief valve malfunction.
•  Replace the fuel delivery pipe.
11
Perform the Fuel Injector Operation Inspection.
(See ENGINE CONTROL SYSTEM OPERATION INSPECTION [MZR 2.3 DISI Turbo].)
Do the fuel injectors operate normally?
Yes
Go to the next step.
No
Repair or replace the malfunctioning parts according to the inspection results.
12
Remove the thermostat.
(See THERMOSTAT REMOVAL/INSTALLATION [MZR 2.3 DISI Turbo].)
Inspect the thermostat.
(See THERMOSTAT INSPECTION [MZR 2.3 DISI Turbo].)
Is there any malfunction?
Yes
Replace the thermostat.
(See THERMOSTAT REMOVAL/INSTALLATION [MZR 2.3 DISI Turbo].)
No
Inspect the throttle body.
(See INTAKE-AIR SYSTEM REMOVAL/INSTALLATION [MZR 2.3 DISI Turbo].)
•  If normal or the problem remains:
―  Replace the PCM (injector driver circuit malfunction).
•  If not:
―  Repair or replace the malfunctioning parts according to the inspection results.
13
Verify test results.
•  If normal, return to the diagnostic index to service any additional symptoms.
•  If a malfunction remains, inspect the related Service 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.