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

BME010300000W10

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 REPAIR PROCEDURE" and "AFTER REPAIR PROCEDURE" described in this manual.
  (See BEFORE REPAIR PROCEDURE [L3].)
  (See AFTER REPAIR PROCEDURE [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 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 okay?
Yes
Go to next step.
No | Service as necessary. Repeat Step 1.
2 | Connect WDS or equivalent to DLC-2. Retrieve any continuous memory, KOEO and KOER. Are there any DTCs displayed? | Yes | DTC is displayed: Go to appropriate DTC test.
No | No DTC is displayed: Go to next step.
3 | Is engine overheating? | Yes | Go to symptom troubleshooting "No.17 Cooling system concerns - Overheating".
No | Go to next step.
4 |

  Note

  • Following test is for engine running rough idle with A/C on concerns. If other symptoms exist, go to next step.
Connect pressure gauge to A/C low and high pressure side lines.
Start engine and run it at idle.
Turn A/C switch on.
Measure low side and high side pressures.
Are pressures within specifications?

Yes
Go to next step.
No | If A/C is always on, go to symptom troubleshooting "No.24 A/C is always on or A/C compressor runs continuously". For other symptoms, inspect following: • Refrigerant charging amount • Condenser fan operation
5 |

  Note

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

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

• Less than 0.45 V during fuel cut: lean condition

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