NO.8 ENGINE RUNS ROUGH/ROLLING IDLE [MZR 1.3, MZR 1.5]

id0103d7801400

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 disconnected
•  Poor fuel quality
•  Fuse malfunction
•  Ignition wiring malfunction
•  Air leakage from intake-air system
•  Open or short circuit in PCM ground circuit (PCM terminals 2AZ, 2BA, 2BB, 2BD and/or 2BH)
•  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
―  Restriction in fuel line
―  Fuel pump mechanical malfunction
―  Pressure regulator malfunction (built-into fuel pump unit)
―  Fuel leakage from fuel system
―  Check valve malfunction (built-into fuel pump unit)
•  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
•  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 “BEFORE SERVICE PRECAUTION” and “AFTER SERVICE PRECAUTION” described in this manual. (See BEFORE SERVICE PRECAUTION [MZR 1.3, MZR 1.5].) (See AFTER SERVICE PRECAUTION [MZR 1.3, MZR 1.5].)
Caution
•  Disconnecting/connecting the quick release connector without cleaning it may possibly cause damage to 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 IF MALFUNCTION CAUSE IS DRIVE-BY-WIRE CONTROL SYSTEM IDLE LEARNING NOT PERFORMED
•  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 drive-by-wire control system is not completed)
No
Go to the next step.
2
INSPECT RELATED PART CONDITION
•  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 terminals 2AZ, 2BA, 2BB, 2BD and 2BH)
―  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
VERIFY PCM DTC
•  Perform the PCM DTC inspection using the M-MDS.
•  Are any DTCs present?
Yes
Go to the applicable DTC inspection.
(See DTC TABLE [MZR 1.3, MZR 1.5].)
No
Go to the next step.
4
VERIFY IF MALFUNCTION CAUSE IS OVERHEATING
•  Is the engine overheating?
Yes
Go to the symptom troubleshooting “NO.17 COOLING SYSTEM CONCERNS-OVERHEATING”.
(See NO.17 COOLING SYSTEM CONCERNS-OVERHEATING [MZR 1.3, MZR 1.5].)
No
Go to the next step.
5
INSPECT MAF SENSOR SIGNAL
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.
•  Drive the vehicle during monitoring the MAF PID.
•  Is the MAF PID value within the specification?
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 1.3, MZR 1.5].)
Repair or replace the malfunctioning part according to the inspection results.
(See MASS AIR FLOW (MAF)/INTAKE AIR TEMPERATURE (IAT) SENSOR REMOVAL/INSTALLATION [MZR 1.3, MZR 1.5].)
6
DETERMINE IF MALFUNCTION CAUSE IS A/C SYSTEM OR OTHER
Note
•  The following test is for the engine running rough at idle with A/C on concerns. 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?
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 CKP SENSOR AND PULSE WHEEL
•  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
INSPECT CKP SENSOR AIR GAP
•  Measure the gap between CKP sensor and teeth of the crankshaft pulley.
•  Is the gap within the specification?
Yes
Go to the next step.
No
Replace the crankshaft pulley.
9
INSPECT IGNITION SYSTEM RELATED WIRING HARNESS
•  Inspect the ignition coil and related wiring harness condition (intermittent open or short circuit) for all cylinders.
•  Is there any malfunction?
Yes
Repair or replace the malfunctioning part according to the inspection results.
No
Go to the next step.
10
VERIFY SPARK PLUG CONDITION
•  Inspect the spark plug condition.
•  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 restriction.
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
INSPECT DRIVE-BY-WIRE CONTROL SYSTEM OPERATION
•  Perform the Drive-by-wire Control System Inspection.
•  Is there any malfunction?
Yes
Repair or replace the malfunctioning part according to the inspection results.
No
Go to the next step.
12
INSPECT FUEL LINE PRESSURE
•  Install the fuel pressure gauge between fuel pipe and fuel distributor.
•  Start the engine and idle it.
•  Measure the fuel line pressure during idle.
•  Is there any malfunction?
Yes
Low:
•  Inspect the fuel line for restriction.
―  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. (pressure regulator or fuel pump malfunction)
High:
•  Replace the fuel pump unit. (pressure regulator malfunction)
No
Go to the next step.
13
INSPECT FUEL SYSTEM FOR FUEL LEAKAGE
•  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
If there is fuel leakage:
•  Repair or replace the malfunctioning part according to the inspection results.
If there is no leakage:
•  Replace the fuel pump unit.
14
INSPECT FUEL INJECTOR OPERATION
•  Perform the Fuel Injector Operation Inspection.
•  Is there any malfunction?
Yes
Repair or replace the malfunctioning part according to the inspection results.
No
Go to the next step.
15
INSPECT LONG TERM FUEL TRIM
•  Start the engine and idle it.
•  Access the LONGFT1 PID using the M-MDS.
•  Measure the LONGFT1 PID at idle.
•  Is the LONGFT1 PID value between −14 % and +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
DETERMINE IF MALFUNCTION CAUSE IS EVAPORATIVE EMISSION CONTROL SYSTEM OR OTHER
•  Disconnect the vacuum hose between purge solenoid valve and intake manifold from purge solenoid valve side.
•  Plug the open end of the 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 1.3, MZR 1.5].)
•  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
INSPECT EXHAUST SYSTEM
•  Visually inspect the exhaust system part.
•  Is there any malfunction?
Yes
Repair or replace the malfunctioning part according to the inspection results.
No
Go to the next step.
18
VISUALLY INSPECT CMP SENSOR AND PULSE WHEEL
•  Visually inspect the CMP sensor and teeth of the camshaft pulley.
•  Is there any malfunction?
Yes
Repair or replace the malfunctioning part according to the inspection results.
No
Go to the next step.
19
INSPECT EGR VALVE FOR STUCK
•  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 1.3, MZR 1.5].)
No
Go to the next step.
20
INSPECT VARIABLE VALVE TIMING CONTROL SYSTEM OPERATION
•  Perform the Variable Valve Timing Control System Operation Inspection.
•  Is there any malfunction?
Yes
Repair or replace the malfunctioning part according to the inspection results.
No
Go to the next step.
21
INSPECT ENGINE COMPRESSION
•  Inspect the engine compression.
•  Is there any malfunction?
Yes
Repair or replace the malfunctioning part according to the inspection results.
No
Go to the next step.
22
INSPECT PCV VALVE
•  Inspect the PCV valve operation.
•  Is there any malfunction?
Yes
Replace the PCV valve and the oil separator as a single unit.
(See POSITIVE CRANKCASE VENTILATION (PCV) VALVE REMOVAL/INSTALLATION [MZR 1.3, MZR 1.5].)
No
Go to the next step.
23
INSPECT IF MALFUNCTION CAUSE IS EGR VALVE MECHANICAL STUCK OR VALVE TIMING
•  Remove the EGR valve and visually inspect the EGR valve (mechanically stuck).
•  Is there any malfunction?
Yes
Replace the EGR valve.
(See EGR VALVE REMOVAL/INSTALLATION [MZR 1.3, MZR 1.5].)
No
Inspect the valve timing.
Repair or replace the malfunctioning part according to the inspection results.
24
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, replace the PCM.