NO.8 ENGINE RUNS ROUGH/ROLLING IDLE [AJ (3.0L Duratec)]


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 • Ignition system malfunction • 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 (3.0L Duratec)].) (See AFTER SERVICE PRECAUTION [AJ (3.0L Duratec)].)


STEP	INSPECTION	RESULTS	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 okay?	Yes	Go to the next step.
1		No	Service as necessary. Repeat Step 1.
2	• Connect WDS or equivalent to DLC-2. • Turn key to ON (Engine OFF). • Retrieve any DTCs. • Is "PASSED" displayed?	Yes	No DTC is displayed: • Go to the next step.
2		No	DTC is displayed: • Go to appropriate DTC test.
3	• Is engine overheating?	Yes	Go to symptom troubleshooting "No.17 Cooling system concerns - Overheating".
3	• Is engine overheating?	No	Go to the next step.
4	Note • Following test is for engine running rough idle with A/C on concerns. If other symptoms exist, go to the 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 the next step.
4		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 the 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 okay?	Yes	Inspect power steering pressure switch operation and wiring harness between power steering pressure switch connector and PCM connector terminal 31.
5		No	Go to the next step.
6	• Visually inspect CKP sensor and teeth of crankshaft pulley. • Are CKP sensor and teeth of crankshaft pulley okay?	Yes	Go to the next step.
6		No	Replace malfunctioning part.
7	• Inspect ignition coils. • Are ignition coils okay?	Yes	Repair or replace ignition coil.
7	• Inspect ignition coils. • Are ignition coils okay?	No	Go to the 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.
8		No	Install spark plugs on original cylinders. Go to the next step.
9	• Start engine and disconnect IAC valve connector. • Does rpm drop or engine stall?	Yes	Go to the next step.
9		No	Inspect IAC valve and wiring harness.
10	• Install fuel pressure gauge to fuel line. • 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 (3.0L Duratec)])	Yes	Go to the next step.
10		No	Zero or low: Inspect the fuel pump, IFS switch and fuel pump relay related circuit. Inspect clogged fuel line. • If normal replace the fuel pump unit. (See FUEL PUMP UNIT REMOVAL/INSTALLATION [AJ (3.0L Duratec)].) High: Replace the fuel pump unit. (See FUEL PUMP UNIT REMOVAL/INSTALLATION [AJ (3.0L Duratec)].)
11	• Visually inspect for fuel leakage at fuel injector, O-ring, and fuel line. • Service as necessary. • Does fuel line pressure hold after key is turned to OFF?	Yes	Go to the next step.
11		No	Inspect the fuel injector. (See FUEL INJECTOR INSPECTION [AJ (3.0L Duratec)].) • If the fuel injector is normal, replace the fuel pump unit. (See FUEL PUMP UNIT REMOVAL/INSTALLATION [AJ (3.0L Duratec)].)
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 the next step.
12		No	LONGFT1 and LONGFT2 PID is out of specification. Below specification (too rich): • Inspect EVAP control system. - If system is okay, go to Step 14. Above specification (too lean): • Inspect for air leakage at intake-air system components. - If system okay, go to the 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.
13		No	Go to the next step.
14	• Remove and shake PCV valve. • Does PCV valve rattle?	Yes	Go to the next step.
14	• Remove and shake PCV valve. • Does PCV valve rattle?	No	Replace PCV valve.
15	• Is there any deformed exhaust system part?	Yes	Replace suspected part.
15	• Is there any deformed exhaust system part?	No	Go to the next step.
16	• Visually inspect CMP sensor and tooth of camshaft. • Are CMP sensor and tooth of camshaft okay?	Yes	Go to the next step.
16		No	Replace malfunctioning part.
17	• Inspect engine condition while tapping EGR valve housing. • Does engine condition improve?	Yes	Replace EGR valve.
17		No	Go to the next step.
18	• Is engine compression correct?	Yes	Inspect valve timing.
18	• Is engine compression correct?	No	Inspect for causes.
19	• Verify test results. - If okay, 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 PCM.