NO.7 SLOW RETURN TO IDLE [MZR 2.0 DISI i-stop]

id0103d3801300

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
•  Air suction in intake-air system
•  PCM DTC is stored.
•  Cooling system malfunction
•  Cooling fan control system malfunction
•  Erratic signal from CMP sensor
―  Loose installation
―  Damaged trigger wheel (camshaft)
―  Open or short circuit in related wiring harness
•  Erratic signal from CKP sensor
―  Loose installation
―  Damaged trigger wheel (crankshaft pulley)
―  Open or short circuit in related wiring harness
•  Erratic signal to PCM
―  APP sensor or related circuit malfunction
―  ECT sensor or related circuit malfunction
―  MAF sensor or related circuit malfunction
•  Excessive fuel pressure
―  Fuel pressure sensor or related circuit malfunction
―  High pressure fuel pump malfunction
―  Relief valve malfunction (built-in fuel delivery pipe)
―  Spill valve control solenoid valve control circuit malfunction (damage to driver in PCM caused by short circuit to ground system)
―  Spill valve control solenoid valve (built-in high pressure fuel pump) malfunction
•  Incorrect fuel injection timing
•  Fuel injector malfunction
•  Thermostat is stuck open.
•  Throttle body malfunction
•  Injector driver (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 2.0 DISI i-stop].) (See AFTER SERVICE PRECAUTION [MZR 2.0 DISI i-stop].)
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 for 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 parts according to the inspection results.
No
Go to the next step.
2
Connect the M-MDS to the DLC-2.
Switch the ignition to ON (engine off).
Retrieve any DTCs using the M-MDS.
(See ON-BOARD DIAGNOSTIC TEST [MZR 2.0 DISI i-stop].)
Are any DTCs present?
Yes
Go to the applicable DTC inspection.
(See DTC TABLE [MZR 2.0 DISI i-stop].)
No
Go to the next step.
3
Access the ECT PID using the M-MDS.
(See ON-BOARD DIAGNOSTIC TEST [MZR 2.0 DISI i-stop].)
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 2.0 DISI i-stop].)
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 2.0 DISI i-stop].)
Repair or replace the malfunctioning parts 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 related circuit
Is there any malfunction?
Yes
Repair or replace the malfunctioning parts according to the inspection results.
No
Go to the next step.
6
Caution
•  While performing this step, always operate the vehicle in a safe and lawful manner.
•  When the M-MDS is used to observe monitor system status while driving, be sure to have another technician with you, or record the data in the M-MDS using the PID/DATA MONITOR AND RECORD capturing function and inspect later.
Access the following PIDs using the M-MDS:
(See ON-BOARD DIAGNOSTIC TEST [MZR 2.0 DISI i-stop].)
•  APP
•  ECT
•  MAF
Do the PIDs indicate the correct values under the trouble condition?
(See PCM INSPECTION [MZR 2.0 DISI i-stop].)
Yes
Go to the next step.
No
Repair or replace the malfunctioning parts according to the inspection results.
•  If the malfunction remains:
―  Perform the “INTERMITTENT CONCERN TROUBLESHOOTING”.
7
Access the FUEL_PRES PID using the M-MDS.
(See ON-BOARD DIAGNOSTIC TEST [MZR 2.0 DISI i-stop].)
Is the FUEL_PRES PID value within the specification?
(See PCM INSPECTION [MZR 2.0 DISI i-stop].)
Yes
Go to Step 12.
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 2.0 DISI i-stop].)
Is there any malfunction?
Yes
Replace the fuel delivery pipe.
(See FUEL INJECTOR REMOVAL/INSTALLATION [MZR 2.0 DISI i-stop].)
No
Go to Step 12.
10
Switch the ignition to off.
Disconnect the high pressure fuel pump and PCM connectors.
Inspect for continuity between high pressure fuel pump terminal A (wiring harness-side) and body ground.
Is there continuity?
Yes
Repair or replace the wiring harness for a possible short to ground.
•  If the malfunction remains:
―  Replace the PCM. (Damage to driver in PCM)
No
Go to the next step.
11
Replace the high pressure fuel pump.
(See HIGH PRESSURE FUEL PUMP REMOVAL/INSTALLATION [MZR 2.0 DISI i-stop].)
Access the FUEL_PRES PID using the M-MDS.
(See ON-BOARD DIAGNOSTIC TEST [MZR 2.0 DISI i-stop].)
Is the FUEL_PRES PID value within the specification?
(See PCM INSPECTION [MZR 2.0 DISI i-stop].)
Yes
High pressure fuel pump or spill valve control solenoid valve (built-in high pressure pump) malfunction.
•  Symptom troubleshooting is completed.
•  Go to Step 14.
No
Relief valve (built-in fuel delivery pipe) malfunction.
•  Replace the fuel delivery pipe.
12
Perform the Fuel Injector Operation Inspection.
(See ENGINE CONTROL SYSTEM OPERATION INSPECTION [MZR 2.0 DISI i-stop].)
Do the fuel injectors operate properly?
Yes
Go to the next step.
No
Repair or replace the malfunctioning parts according to the inspection results.
13
Cool down the engine.
Remove the thermostat.
(See THERMOSTAT REMOVAL/INSTALLATION [MZR 2.0 DISI i-stop].)
Inspect the thermostat operation.
(See THERMOSTAT INSPECTION [MZR 2.0 DISI i-stop].)
Is there any malfunction?
Yes
Replace the thermostat.
(See THERMOSTAT REMOVAL/INSTALLATION [MZR 2.0 DISI i-stop].)
No
Inspect the throttle body.
(See THROTTLE BODY INSPECTION [MZR 2.0 DISI i-stop].)
Repair or replace the malfunctioning parts according to the inspection results.
•  If the throttle body is normal or the problem remains:
―  Replace the PCM (injector driver malfunction).
14
Verify the test results.
•  If normal, return to the diagnostic index to service any additional symptoms. (See SYMPTOM DIAGNOSTIC INDEX [MZR 2.0 DISI i-stop].)
•  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, replace the PCM. (See PCM REMOVAL/INSTALLATION [MZR 2.0 DISI i-stop].)