NO.8 ENGINE RUNS ROUGH/ROLLING IDLE [MZR 1.5, MZR 1.6]

id0103e0801400

8

ENGINE RUNS ROUGH/ROLLING IDLE
DESCRIPTION
•  The engine speed fluctuates between the specified idle speed and lower speed and the engine shakes excessively.
•  The idle speed is too slow and the engine shakes excessively.
POSSIBLE CAUSE
•  Electrical connector disconnection
•  Poor fuel quality
•  Fuse malfunction
•  Ignition wiring malfunction
•  Air leakage from intake-air system
•  Open or short circuit in PCM ground circuit
•  Improper operation of throttle valve
•  Continuous memory DTC is stored
•  Engine overheating
•  MAF sensor and related wiring harness malfunction
•  Improper operation of A/C system
•  CKP sensor and teeth of the crankshaft pulley
•  Ignition coil and related wiring harness
•  Spark plug malfunction
•  Improper operation of drive-by-wire control system
•  Inadequate fuel pressure
•  Pressure regulator (built-in fuel pump unit) malfunction
•  Improper operation of fuel injector
•  EVAP control system malfunction
•  Purge solenoid valve malfunction (stuck open)
•  Restriction in exhaust system
•  CMP sensor and teeth of camshaft pulley
•  EGR valve malfunction (with EGR system)
•  Improper operation of variable valve timing control system
•  Low engine compression
•  PCV valve malfunction
•  Valve timing malfunction
•  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 injuries or death and damage. Fuel can also irritate skin and eyes. To prevent this, always complete the "BEFORE SERVICE PRECAUTION" and "AFTER SERVICE PRECAUTION" described in this manual. (See BEFORE SERVICE PRECAUTION [MZR 1.5, MZR 1.6].) (See AFTER SERVICE PRECAUTION [MZR 1.5, MZR 1.6].)
Caution
•  If there is foreign material on the connecting area of the quick release connector, it might damage the connector or fuel pipe. To prevent this, disconnect the connector and clean the connecting area before connecting.

Diagnostic procedure

STEP

INSPECTION

ACTION
1
Start the engine and warm it up completely.
Idle the engine for 5 min.
Is the symptom disappeared?
Yes
Symptom troubleshooting completed. (Cause of this symptom is that the idle learning of drive-by-wire control system is not completed.)
No
Go to the next step.
2
Inspect the following:
•  Electrical connections
•  External fuel shut off or accessory (kill switch, alarm etc.)
•  Fuel quality (such as proper octane, contamination, winter/summer blend)
•  Fuses
•  Ignition wiring
•  No air leakage from intake-air system
•  PCM ground circuit (PCM terminal 2AZ, 2BA, 2BH, 2BD and/or 2BB)
•  Proper sealing of intake manifold and components attached to intake manifold: EGR valve (with EGR system)
•  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
Connect the M-MDS to the DLC-2.
Perform the KOEO or KOER self test.
(See KOEO/KOER SELF TEST [MZR 1.5, MZR 1.6].)
Are any continuous memory DTCs present?
Yes
Go to the appropriate DTC inspection.
(See DTC TABLE [MZR 1.5, MZR 1.6].)
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 1.5, MZR 1.6].)
No
Go to the next step.
5
Access the MAF PID using the M-MDS.
(See ON-BOARD DIAGNOSTIC TEST [MZR 1.5, MZR 1.6].)
Monitoring the MAF PID with driving the vehicle.
Is the MAF PID value within the specification?
(See PCM INSPECTION [MZR 1.5, MZR 1.6].)
Yes
Go to the next step.
No
Inspect the MAF sensor and related wiring harness for open or short circuit.
(See MASS AIR FLOW (MAF) SENSOR INSPECTION [MZR 1.5, MZR 1.6].)
Repair or replace the malfunctioning part according to the inspection results.
(See MASS AIR FLOW (MAF)/INTAKE AIR TEMPERATURE (IAT) SENSOR REMOVAL/INSTALLATION [MZR 1.5, MZR 1.6].)
6
Note
•  Following test is for engine running rough idle with the A/C on concerns. If other symptoms exist, go to the next step.
Connect the 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.
(See REFRIGERANT PRESSURE CHECK.)
Are the pressures within the specifications?
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.
Is there any malfunction?
Yes
Repair or replace the malfunctioning part according to the inspection results.
No
Go to the next step.
8
Measure the gap between the CKP sensor and teeth of crankshaft pulley.
Is the gap within the specification?
(See CRANKSHAFT POSITION (CKP) SENSOR INSPECTION [MZR 1.5, MZR 1.6].)
Yes
Go to the next step.
No
Replace the crankshaft pulley.
9
Inspect the ignition coil and related wiring harness condition (intermittent open or short circuit) for all cylinders.
(See IGNITION COIL INSPECTION [MZR 1.5, MZR 1.6].)
Is there any malfunction?
Yes
Repair or replace the malfunctioning part according to the inspection results.
No
Go to the next step.
10
Inspect the spark plug condition.
(See SPARK PLUG INSPECTION [MZR 1.5, MZR 1.6].)
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 the fuel injector.
Spark plug is grayish white:
•  Inspect for clogged the fuel injector.
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.
11
Perform the Drive-by-wire Control System Inspection.
(See ENGINE CONTROL SYSTEM OPERATION INSPECTION [MZR 1.5, MZR 1.6].)
Does the throttle body operate properly?
Yes
Go to the next step.
No
Repair or replace the malfunctioning part according to the inspection results.
12
Install the fuel pressure gauge between the fuel pipe and the fuel distributor.
Start the engine and idle it.
Measure the fuel line pressure during idle.
Is the fuel line pressure correct during idle?
(See FUEL LINE PRESSURE INSPECTION [MZR 1.5, MZR 1.6].)
Yes
Go to the next step.
No
Low:
•  Inspect the fuel line for clogging.
―  If there is no malfunction:
•  Replace the fuel pump unit.
―  If there is a malfunction:
•  Repair or replace the malfunctioning part according to the inspection results.
High:
•  Replace the fuel pump unit.
13
Visually inspect the fuel injector, O-ring, and fuel line for fuel leakage.
Does the fuel line pressure hold after the ignition switch is turned off?
(See FUEL LINE PRESSURE INSPECTION [MZR 1.5, MZR 1.6].)
Yes
Go to Step 15.
No
Go to the next step.
14
Perform the Fuel Injector Operation Inspection.
(See ENGINE CONTROL SYSTEM OPERATION INSPECTION [MZR 1.5, MZR 1.6].)
(See FUEL INJECTOR INSPECTION [MZR 1.5, MZR 1.6].)
Is there any malfunction?
Yes
Repair or replace the malfunctioning part according to the inspection results.
No
Go to the next step.
15
Start the engine and idle it.
Access the LONGFT1 PID using the M-MDS.
(See ON-BOARD DIAGNOSTIC TEST [MZR 1.5, MZR 1.6].)
Monitor the LONGFT1 PID at idle.
Is the PID value between −14%—14%?
Yes
Go to the next step.
No
Less than the specification (too rich):
•  Inspect the EVAP control system.
―  If the system is normal:
•  Go to Step 17.
Greater than the specification (too lean):
•  Inspect for air leakage at intake-air system components.
―  If the system is normal:
•  Go to the next step.
16
Disconnect the vacuum hose between the purge solenoid valve and the intake manifold from the purge solenoid valve side.
Plug the opening end of vacuum hose.
Start the engine.
Does the engine condition improve?
Yes
Inspect the purge solenoid valve (stuck open mechanically).
(See PURGE SOLENOID VALVE INSPECTION [MZR 1.5, MZR 1.6].)
•  If the purge solenoid valve has a malfunction:
―  Replace the purge solenoid valve.
•  If the purge solenoid valve is normal:
―  Inspect the EVAP control system.
―  Repair or replace the malfunctioning part according to the inspection results.
No
Go to the next step.
17
Visually inspect the exhaust system part.
Is there any deformed exhaust system part?
Yes
Repair or replace the malfunctioning part according to the inspection results.
No
Go to the next step.
18
Visually inspect the CMP sensor and teeth of camshaft pulley.
Is there any malfunction?
Yes
Repair or replace the malfunctioning part according to the inspection results.
No
With EGR system:
•  Go to the next step.
Without EGR system:
•  Go to Step 20.
19
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 1.5, MZR 1.6].)
No
Go to the next step.
20
Perform the Variable Valve Timing Control System Operation Inspection.
(See ENGINE CONTROL SYSTEM OPERATION INSPECTION [MZR 1.5, MZR 1.6].)
Does the variable valve timing control system operate properly?
Yes
Go to the next step.
No
Repair or replace the malfunctioning part according to the inspection results.
21
Inspect the engine compression.
(See COMPRESSION INSPECTION [MZR 1.5, MZR 1.6].)
Is there any malfunction?
Yes
Inspect for cause.
Repair or replace the malfunctioning part according to the inspection results.
No
Go to the next step.
22
Inspect the PCV valve operation.
(See POSITIVE CRANKCASE VENTILATION (PCV) VALVE INSPECTION [MZR 1.5, MZR 1.6].)
Is there any malfunction?
Yes
Replace the PCV valve.
(See PURGE SOLENOID VALVE REMOVAL/INSTALLATION [MZR 1.5, MZR 1.6].)
No
With EGR system:
•  Go to the next step.
Without EGR system:
•  Inspect the valve timing.
•  Repair or replace the malfunctioning part according to the inspection results.
23
Remove the EGR valve and visually inspect the EGR valve (mechanically stuck).
(See EGR VALVE REMOVAL/INSTALLATION [MZR 1.5, MZR 1.6].)
Is there any malfunction?
Yes
Replace the EGR valve.
(See EGR VALVE REMOVAL/INSTALLATION [MZR 1.5, MZR 1.6].)
No
Inspect the valve timing.
Repair or replace the malfunctioning part according to the inspection results.
24
Verify the test results.
•  If normal, return to diagnostic index to service any additional symptoms. (See SYMPTOM DIAGNOSTIC INDEX [MZR 1.5, MZR 1.6].)
•  If malfunction remains, inspect related Service information perform repair or diagnosis.
―  If vehicle repaired, troubleshooting completed.
―  If vehicle not repaired or additional diagnostic information not available, replace the PCM. (See PCM REMOVAL/INSTALLATION [MZR 1.5, MZR 1.6].)