NO.8 ENGINE RUNS ROUGH/ROLLING IDLE [MZR 1.8, MZR 2.0, MZR 2.5]

id0103d4801400

8

ENGINE RUNS ROUGH/ROLLING IDLE
DESCRIPTION
•  Engine speed fluctuates between specified idle speed and lower speed, and engine shakes excessively.
•  Idle speed is too slow and engine shakes excessively.
POSSIBLE CAUSE
•  Idle learning of electronic throttle control system is not completed
•  Electrical connector disconnection
•  External fuel shut off or accessory
•  Poor fuel quality
•  Fuse malfunction
•  Ignition wiring malfunction
•  Air leakage from intake air system
•  Vacuum leakage
•  PCM ground circuit (1E, 1F, 1G or 1BE) malfunction
•  Improper installation EGR valve
•  Improper operation of electronic throttle control system
•  PCM DTC is stored
•  Engine overheating
•  MAF sensor or related wiring harness malfunction
•  Improper operation of A/C system
•  CKP sensor and teeth of crankshaft pulley malfunction
•  Ignition coil or related wiring harness malfunction
•  Spark plug malfunction
•  Excessive or insufficient fuel pressure
―  Fuel pump relay or fuel pump circuit malfunction
―  Clogging fuel line
―  Pressure regulator malfunction (built-in fuel pump unit)
―  Fuel pump unit malfunction
•  Fuel leakage from fuel system
•  Fuel injector malfunction
•  Purge solenoid valve malfunction
•  Evaporative emission control system malfunction
•  Exhaust system part malfunction
•  CMP sensor and teeth of camshaft malfunction
•  EGR valve malfunction
•  Improper operation of variable valve timing control system (MZR 2.0, MZR 2.5)
•  Low engine compression
•  PCV valve malfunction
•  Improper valve timing
Warning
•  The following troubleshooting flow chart contains the fuel system diagnosis and repair procedures. Read the following warnings before servicing the fuel system:
―  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 injuries 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 1.8, MZR 2.0, MZR 2.5].) (See AFTER SERVICE PRECAUTION [MZR 1.8, MZR 2.0, MZR 2.5].)
Caution
•  Disconnecting/connecting the quick release connector without cleaning it may cause damage to the fuel pipe and the 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
Start the engine and warm it up completely.
Idle the engine for 5 min or more.
Does the symptom disappear?
Yes
Symptom troubleshooting is completed. (cause of this symptom is that the idle learning for electronic throttle control system is not completed)
No
Go to the next step.
2
Inspect the following:
•  Electrical connections
•  External fuel shut off or accessory (such as kill switch, alarm)
•  Fuel quality (such as proper octane, contamination, winter/summer blend)
•  Vacuum leakage
•  Fuses
•  Ignition wiring
•  No air leakage from intake air system
•  PCM ground circuit (1E, 1F, 1G or 1BE)
•  Proper sealing of intake manifold and components attached to intake manifold: such as EGR valve
•  Smooth operation of throttle valve
Is there any malfunction?
Yes
Repair or replace the malfunctioning part according to the inspection results.
Repeat Step 2.
No
Go to the next step.
3
Perform the PCM DTC inspection using the M-MDS.
(See ON-BOARD DIAGNOSTIC TEST [MZR 1.8, MZR 2.0, MZR 2.5].)
Are any DTCs present?
Yes
Go to the applicable DTC inspection.
(See DTC TABLE [MZR 1.8, MZR 2.0, MZR 2.5].)
No
Go to the next step.
4
Is the engine overheating?
Yes
Go to the symptom troubleshooting “NO.17 COOLING SYSTEM CONCERNS-OVERHEATING”.
(See NO.17 COOLING SYSTEM CONCERNS-OVERHEATING [MZR 1.8, MZR 2.0, MZR 2.5].)
No
Go to the next step.
5
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 MAF PID using the M-MDS.
(See ON-BOARD DIAGNOSTIC TEST [MZR 1.8, MZR 2.0, MZR 2.5].)
Drive the vehicle during monitoring the MAF PID.
Is the MAF PID value within the specification?
(See ON-BOARD DIAGNOSTIC TEST [MZR 1.8, MZR 2.0, MZR 2.5].)
Yes
Go to the next step.
No
Inspect for an open or short circuit in the MAF sensor and related wiring harness.
Repair or replace the malfunctioning part according to the inspection results.
6
Note
•  The following test is for the engine running at rough idle with A/C on. If other symptoms exist, go to the next step.
Connect a pressure gauge to the A/C low and high pressure side lines.
Start the engine and idle it.
Turn the A/C switch on.
Measure the low side and high side pressures.
Are the pressures within the specification?
(See REFRIGERANT PRESSURE CHECK.)
Yes
Go to the next step.
No
If the A/C is always on:
•  Go to the symptom troubleshooting “NO.24 A/C IS ALWAYS ON OR A/C COMPRESSOR RUNS CONTINUOUSLY”.
For other symptoms:
•  Inspect the following:
―  Refrigerant charging amount
―  Condenser fan operation
•  Repair or replace the malfunctioning part according to the inspection results.
7
Visually inspect the CKP sensor and teeth of the crankshaft pulley.
(See CRANKSHAFT POSITION (CKP) SENSOR INSPECTION [MZR 1.8, MZR 2.0, MZR 2.5].)
Is there any malfunction?
Yes
Repair or replace the malfunctioning part according to the inspection results.
No
Go to the next step.
8
Inspect the ignition coil related wiring harness condition (intermittent open or short circuit) for all cylinders.
Is there any malfunction?
Yes
Repair or replace the suspected wiring harness.
No
Go to the next step.
9
Inspect the spark plug condition.
(See SPARK PLUG INSPECTION [MZR 1.8, MZR 2.0, MZR 2.5].)
Is the spark plug wet, covered with carbon or grayish white?
Yes
Spark plug is wet or covered with carbon:
•  Inspect for fuel leakage from fuel injector.
Spark plug is grayish white:
•  Inspect the fuel injector for clogging.
Repair or replace the malfunctioning part according to the inspection results.
No
Install the spark plugs on original cylinders, then go to the next step.
10
Perform the Electronic Throttle Control System Inspection.
(See ENGINE CONTROL SYSTEM OPERATION INSPECTION [MZR 1.8, MZR 2.0, MZR 2.5].)
Is there any malfunction?
Yes
Repair or replace the malfunctioning part according to the inspection results.
No
Go to the next step.
11
Inspect the fuel line pressure.
(See FUEL LINE PRESSURE INSPECTION [MZR 1.8, MZR 2.0, MZR 2.5].)
Is there any malfunction?
Yes
Zero or low:
•  Inspect the fuel pump relay and the fuel pump circuit.
•  Inspect the fuel line for clogging.
―  If there is any malfunction:
•  Repair or replace the malfunctioning part according to the inspection results.
―  If there is no malfunction:
•  Replace the fuel pump unit.
High:
•  Replace the fuel pump unit.
No
Go to the next step.
12
Visually inspect for fuel leakage at the fuel injector O-ring and fuel line.
Is the fuel line pressure held after the ignition is off?
Yes
Go to the next step.
No
Inspect the fuel injector.
(See FUEL INJECTOR INSPECTION [MZR 1.8, MZR 2.0, MZR 2.5].)
•  If the fuel injector has malfunction:
―  Replace the fuel injector.
•  If the fuel injector is normal:
―  Replace the fuel pump unit.
13
Start the engine and idle it.
Access the LONGFT1 PID using the M-MDS.
(See ON-BOARD DIAGNOSTIC TEST [MZR 1.8, MZR 2.0, MZR 2.5].)
Measure the LONGFT1 PID at idle.
Is the LONGFT1 PID value between −14% and +14%?
Yes
Go to the next step.
No
Less than specification (too rich):
•  Inspect the EVAP control system.
Greater than specification (too lean):
•  Inspect for air leakage at the intake air system components.
―  If there is any malfunction:
•  Repair or replace the malfunctioning part according to the inspection results.
―  If there is no malfunction:
•  Go to the next step.
14
Disconnect the vacuum hose between the purge solenoid valve and the intake manifold from the purge solenoid valve side.
Plug the open end of the vacuum hose.
Switch the ignition to ON (engine off).
Is the engine stall now eliminated?
Yes
Inspect the following:
•  Purge solenoid valve
•  Evaporative emission control system
Repair or replace the malfunctioning part according to the inspection results.
No
Go to the next step.
15
Visually inspect the exhaust system part.
(See EXHAUST SYSTEM INSPECTION [MZR 1.8, MZR 2.0, MZR 2.5].)
Is there any malfunction?
Yes
Repair or replace the malfunctioning part according to the inspection results.
No
Go to the next step.
16
Visually inspect the CMP sensor and teeth of the camshaft.
(See CAMSHAFT POSITION (CMP) SENSOR INSPECTION [MZR 1.8, MZR 2.0, MZR 2.5].)
Is there any malfunction?
Yes
Repair or replace the malfunctioning part according to the inspection results.
No
Go to the next step.
17
Inspect the engine condition while tapping the EGR valve housing.
Does the engine condition improve?
Yes
Replace the EGR valve.
(See EGR VALVE REMOVAL/INSTALLATION [MZR 1.8, MZR 2.0, MZR 2.5].)
No
MZR 1.8:
•  Go to Step 19.
MZR 2.0, MZR 2.5:
•  Go to the next step.
18
Perform the Variable Valve Timing Control System Operation Inspection.
(See ENGINE CONTROL SYSTEM OPERATION INSPECTION [MZR 1.8, MZR 2.0, MZR 2.5].)
Is there any malfunction?
Yes
Repair or replace the malfunctioning part according to the inspection results.
No
Go to the next step.
19
Inspect the engine compression.
(See COMPRESSION INSPECTION [MZR 1.8, MZR 2.0, MZR 2.5].)
Is there any malfunction?
Yes
Repair or replace the malfunctioning part according to the inspection results.
No
Go to the next step.
20
Inspect the PCV valve.
(See POSITIVE CRANKCASE VENTILATION (PCV) VALVE INSPECTION [MZR 1.8, MZR 2.0, MZR 2.5].)
Is there any malfunction?
Yes
Replace the PCV valve.
(See POSITIVE CRANKCASE VENTILATION (PCV) VALVE REMOVAL/INSTALLATION [MZR 1.8, MZR 2.0, MZR 2.5].)
No
Inspect the valve timing.
(See VARIABLE VALVE TIMING ACTUATOR INSPECTION [MZR 2.0, MZR 2.5].)
Repair or replace the malfunctioning part according to the inspection results.
21
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.
―  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.