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NO.8 ENGINE RUNS ROUGH/ROLLING IDLE [AJ] (VIN: JM0 LW10J300 301406-, JMZ LW69J7*# 307683-, JM8 LW28J**# 301514-, JM8 LW28A**# 301514- (Assumed))

BME010300000W06

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 improper operation • Spark leakage from ignition coils • Purge solenoid valve malfunction • IAC valve improper operation
• EGR valve malfunction
• Erratic or no signal from CMP sensor
• Low engine compression
• 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 mechanical malfunction
• Fuel leakage from fuel injector
• Fuel injector clogging
• Engine overheating
• Vacuum leakage

  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 REPAIR PROCEDURE" and "AFTER REPAIR PROCEDURE" described in this manual.
  (See BEFORE SERVICE PRECAUTION [AJ].)
  (See AFTER SERVICE PRECAUTION [AJ].)

Diagnostic procedure

STEP | INSPECTION | ACTION
--- | --- | ---
1 | • Verify following:

  - External fuel shut off or accessory (kill switch, alarm etc.)
  - Fuel quality: 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 next step.
No | Service as necessary. Repeat Step 1.
2 | • Connect WDS or equivalent to DLC-2. • Turn ignition switch to ON (Engine OFF). • Retrieve any DTCs. • Is "PASSED" displayed? | Yes | No DTC is displayed: • Go to next step.
No | DTC is displayed: • Go to appropriate DTC test.
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 reading pressures within specifications?
Yes
Go to next step.
No | If A/C is always on, go to symptom troubleshooting "No.24 A/C always on/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 SW PID.
• Inspect if PSP SW PID is ON while turning steering wheel right to left.
• Is PSP SW PID normal?
Yes
Inspect power steering pressure switch operation and wiring harness between power steering pressure switch connector and PCM connector terminal 55.
No | Go to next step.
6 | • Visually inspect CKP sensor and teeth of crankshaft pulley. • Are CKP sensor and teeth of crankshaft pulley normal? | Yes | Go to next step.
No | Replace malfunctioning part.
7 | • Inspect ignition coils. • Are ignition coils normal? | Yes | Repair or replace ignition coil.
No | Go to next step.
8 | • Inspect spark plug conditions. • 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.
9 | • 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.
10 | • Install fuel pressure gauge between pulsation damper 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 [AJ].) | Yes | Go to next step.
No | Zero or low: • Inspect fuel pump circuit. • Inspect for open fuel pump relief valve. • Inspect for fuel leakage inside pressure regulator. • Inspect for clogged main fuel line. High:
• Inspect pressure regulator for high pressure cause.
• Inspect for clogged fuel return line.
11 | • 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 to OFF? | Yes | Go to next step.
No | Inspect pressure regulator diaphragm condition. • If condition is normal, inspect fuel injector. • If condition is not normal, replace pressure regulator.
12 | • Connect WDS or equivalent to DLC-2. • Start the engine and run it at idle. • Access LONGFT1 and LONGFT2 PID. • Measure LONGFT1 and LONGFT2 PID at idle. • Is PID value within -15% - +15%? | Yes | Go to next step.
No | LONGFT1 and LONGFT2 PID is out of specification. Below specification (too rich): • Inspect EVAP control system.

  - If system is normal, go to Step 14.

Above specification (too lean):
• Inspect for air leakage at intake-air system components.

  - If system normal, go to next step.

13 | • 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.
14 | • Remove and shake PCV valve. • Does PCV valve rattle? | Yes | Go to next step.
No | Replace PCV valve.
15 | • Inspect for restriction in the exhaust system. • Is there any restriction? | Yes | Inspect exhaust system.
No | Go to next step.
16 | • Visually inspect CMP sensor and tooth of camshaft. • Are CMP sensor and tooth of camshaft normal? | Yes | Go to next step.
No | Replace malfunctioning part.
17 | • Inspect engine condition while tapping EGR valve housing. • Does engine condition improve? | Yes | Replace EGR valve.
No | Go to next step.
18 | • Is engine compression correct? | Yes | Inspect valve timing.
No | Inspect for causes.
19 | • Verify test results.

  - If normal, return to diagnostic index to service any additional symptoms.
  - If malfunction remains, inspect related Service Information and perform repair or diagnosis.

  • If vehicle is repaired, troubleshooting completed.
  • If vehicle is not repaired or additional diagnostic information is not available, replace or reprogram PCM.