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NO.8 ENGINE RUNS ROUGH/ROLLING IDLE [L3]

BME010300103246

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 | • Air leakage from intake-air system parts • A/C system operation is improper • Spark leakage from high-tension leads • Spark plug malfunction • Purge solenoid valve malfunction
• IAC valve improper operation
• EGR valve malfunction
• Erratic or no signal from CMP sensor
• Low engine compression
• Improper valve timing
• Erratic signal from CKP sensor
• Poor fuel quality
• PCV valve malfunction
• Air cleaner restriction
• Restriction in exhaust system
• Disconnected electrical connectors
• Inadequate fuel pressure
• Fuel pump body mechanical malfunction
• Improper load signal input
• Fuel line restriction or clogging
• Improper fuel injection control operation
• Fuel leakage from fuel injector
• Fuel injector clogging
• Engine overheating
• Vacuum leakage
• Pressure regulator malfunction

  Warning
The following troubleshooting flow chart contains fuel system diagnosis and repair procedures. Read 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 [L3].)
  (See AFTER SERVICE PRECAUTION [L3].)

  Caution

  • Disconnecting/connecting quick release connector without cleaning it may possibly cause damage to fuel pipe and quick release connector. Always clean 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 | Verify the following: • External fuel shut off or accessory (kill switch, alarm etc.) • Fuel quality (e.g. proper octane, contamination, winter/summer blend) • No air leakage from intake-air system • Proper sealing of intake manifold and components attached to intake manifold: EGR valve, IAC valve
• Ignition wiring
• Electrical connections
• Fuses
• Smooth operation of throttle valve
Are all items normal?
Yes
Go to the next step.
No | Service if necessary. Repeat Step 1.
2 | Connect the WDS or equivalent to the DLC-2. Retrieve any continuous memory, KOEO and KOER. Are there any DTCs displayed? | Yes | DTC is displayed: Go to the applicable DTC inspection. (See DTC TABLE [L3].)
No | No DTC is displayed: Go to the next step.
3 | Is engine overheating? | Yes | Go to symptom troubleshooting "No.17 Cooling system concerns - Overheating". (See NO.17 COOLING SYSTEM CONCERNS-OVERHEATING [L3].)
No | Go to the next step.
4 |

  Note

  • The following test is for the engine running rough idle with the 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 run it at idle.
Turn the A/C switch on.
Measure low side and high side pressures.
Are pressures within the specifications?

Yes
Go to the next step.
No | If the A/C is always on, go to symptom troubleshooting "No.24 A/C is always on or A/C compressor runs continuously". (See NO.24 A/C IS ALWAYS ON OR A/C COMPRESSOR RUNS CONTINUOUSLY [L3].) For other symptoms, inspect the following: • Refrigerant charging amount
• Condenser fan operation
5 |

  Note

  • The following test is for the engine running rough with the P/S on. If other symptoms exist, go to the next step.
Start the engine and run it at idle.
Access PSP PID.
Inspect if PSP PID is on while turning the steering wheel right to left.
Is PSP PID normal?

Yes
Inspect the power steering pressure switch operation and the wiring harness between P/S pressure switch connector and PCM connector terminal 1Z.
No | Go to the next step.
6 | Visually inspect the CKP sensor and teeth of the crankshaft pulley. Are the CKP sensor and teeth of the crankshaft pulley normal? | Yes | Go to the next step.
No | Replace the malfunctioning part.
7 | Measure the gap between the CKP sensor and teeth of the crankshaft pulley. Specification 0.5-1.5 mm {0.020-0.075 in} Is the gap within the specification? | Yes | Go to the next step.
No | Adjust the CKP sensor.
8 | Inspect for cracks on the high-tension leads. Are there any cracks on high-tension leads? | Yes | Repair the high-tension leads.
No | Go to the next step.
9 | 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 the fuel injector. Spark plug is grayish white: Inspect for the clogged fuel injector.
No | Install the spark plugs on original cylinders. Go to the next step.
10 | Start the engine and disconnect the IAC valve connector. Does rpm drop or the engine stall? | Yes | Go to the next step.
No | Inspect the IAC valve and the wiring harness.
11 | Install a fuel pressure gauge between the fuel pipe and the fuel distributor. Start the engine and run it at idle. Measure fuel line pressure at idle. Is fuel line pressure correct at idle? (See FUEL LINE PRESSURE INSPECTION [L3].) | Yes | Go to the next step.
No | Zero or low: Inspect for clogged fuel line. If normal, replace the fuel pump unit. (See FUEL PUMP UNIT REMOVAL/INSTALLATION [L3].) High:
Replace the fuel pump unit.
(See FUEL PUMP UNIT REMOVAL/INSTALLATION [L3].)
12 | Visually inspect for fuel leakage at the fuel injector, O-ring, and fuel line. Service if necessary. Does fuel line pressure hold after the ignition switch is turned off? (See FUEL LINE PRESSURE INSPECTION [L3].) | Yes | Go to the next step.
No | Inspect the fuel injector. If the fuel injector is normal, replace the fuel pump unit. (See FUEL PUMP UNIT REMOVAL/INSTALLATION [L3].)
13 | Connect the WDS or equivalent to the DLC-2. Start the engine and run it at idle. Access O2S11 PID. Is O2S11 PID normal? • More than 0.45 V when the accelerator pedal is suddenly depressed: rich condition

• Less than 0.45 V during fuel cut: lean condition

Yes
Go to the next step.
No | Inspect and repair or replace the malfunctioning HO2S, the wiring harness, connector or terminal, then go to the next step.
14 | Disconnect vacuum hose between the purge solenoid valve and the intake manifold from the purge solenoid valve side. Plug opening end of vacuum hose. Start the engine. Does the engine condition improve? | Yes | Inspect if the purge solenoid valve sticks open mechanically. Inspect the EVAP control system.
No | Go to the next step.
15 | Remove and shake the PCV valve. Does the PCV valve rattle? | Yes | Go to the next step.
No | Replace the PCV valve.
16 | Inspect for restriction in the exhaust system. Is there any restriction? | Yes | Inspect the exhaust system.
No | Go to the next step.
17 | Visually inspect the CMP sensor and teeth of the camshaft. Are the CMP sensor and teeth of the camshaft normal? | Yes | Go to the next step.
No | Replace malfunctioning part.
18 | 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 [L3].)
No | Go to the next step.
19 | Is the engine compression correct? | Yes | Inspect the valve timing.
No | Inspect for causes.
20 | Verify test results. • If normal, return to diagnostic index to service any additional symptoms. • If malfunction remains, replace PCM.