#
NO.8 ENGINE RUNS ROUGH/ROLLING IDLE [AJ] (VIN: JMZ LW19J7*# 300001-, JM0 LW10J300 300001-301405, JM6 LW10J300 300001-, JM8 LW28J**# 300001-301513)

BME010300103213

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

Diagnostic procedure

STEP | INSPECTION | ACTION
--- | --- | ---
1 | • Verify the 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 the next step.
No | Service if necessary. Repeat Step 1.
2 | • Connect the WDS or equivalent to the DLC-2. • Turn the ignition switch to the ON position (Engine off). • Retrieve any DTCs. • Is "PASSED" displayed? | Yes | No DTC is displayed: • Go to the next step.
No | DTC is displayed: • Go to the applicable DTC inspection. (See DTC TABLE [AJ] (VIN: JMZ LW19J7*# 300001-, JM0 LW10J300 300001-301405, JM6 LW10J300 300001-, JM8 LW28J**# 300001-301513).)
3 | • Is the engine overheating? | Yes | Go to symptom troubleshooting "No.17 Cooling system concerns - Overheating". (See NO.17 COOLING SYSTEM CONCERNS-OVERHEATING [AJ] (VIN: JMZ LW19J7*# 300001-, JM0 LW10J300 300001-301405, JM6 LW10J300 300001-, JM8 LW28J**# 300001-301513).)
No | Go to the next step.
4 |

  Note

  • The following test is for the engine running rough idle with A/C on concerns. If other symptoms exist, go to the next step.

• Connect a pressure gauge to 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 reading 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 always on/A/C compressor runs continuously". (See NO.24 A/C ALWAYS ON/A/C COMPRESSOR RUNS CONTINUOUSLY [AJ] (VIN: JMZ LW19J7*# 300001-, JM0 LW10J300 300001-301405, JM6 LW10J300 300001-, JM8 LW28J**# 300001-301513).)
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 SW PID.
• Inspect if PSP SW PID is ON while turning the steering wheel right to left.
• Is PSP SW PID normal?
Yes
Inspect the power steering pressure switch operation and the wiring harness between power steering pressure switch connector and PCM connector terminal 31.
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 | • Inspect the ignition coils. • Are the ignition coils normal? | Yes | Repair or replace the ignition coil.
No | Go to the next step.
8 | • Inspect the spark plug conditions. • 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 spark plugs on original cylinders. Go to the next step.
9 | • 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.
10 | • Install a fuel pressure gauge between the pulsation damper and the fuel distributor. • Start the engine and run it at idle. • Measure the fuel line pressure at idle. • Is fuel line pressure correct at idle? (See FUEL LINE PRESSURE INSPECTION [AJ].) | Yes | Go to the next step.
No | Zero or low: • Inspect the fuel pump circuit. • Inspect for open fuel pump relief valve. • Inspect for fuel leakage inside the pressure regulator. • Inspect for the clogged main fuel line. High:
• Inspect the pressure regulator for high pressure cause.
• Inspect for clogged fuel return line.
11 | • Visually inspect for fuel leakage at the fuel injector, O-ring, and fuel line. • Service if necessary. • Does the fuel line pressure hold after the ignition switch is turned off? | Yes | Go to the next step.
No | Inspect the pressure regulator diaphragm condition. • If the condition is normal, inspect the fuel injector. • If the condition is not normal, replace the pressure regulator.
12 | • Connect the WDS or equivalent to the 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 the next step.
No | LONGFT1 and LONGFT2 PID is out of the specification. Below specification (too rich): • Inspect the EVAP control system.

  - If the system is normal, go to Step 14.

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

  - If the system normal, go to the next step.

13 | • Disconnect the vacuum hose between the purge solenoid valve and the intake manifold from the purge solenoid valve side. • Plug opening end of the 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.
14 | • Remove and shake the PCV valve. • Does the PCV valve rattle? | Yes | Go to the next step.
No | Replace the PCV valve.
15 | • Inspect for restriction in the exhaust system. • Is there any restriction? | Yes | Inspect the exhaust system.
No | Go to the next step.
16 | • Visually inspect the CMP sensor and a tooth of the camshaft. • Are the CMP sensor and a tooth of the camshaft normal? | Yes | Go to the next step.
No | Replace the malfunctioning part.
17 | • Inspect the engine condition while tapping the EGR valve housing. • Does the engine condition improve? | Yes | Replace the EGR valve.
No | Go to the next step.
18 | • Is the engine compression correct? | Yes | Inspect the 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 the PCM.