NO.7 ENGINE RUNS ROUGH/ROLLING IDLE [F2]

id010394912700

7

ENGINE RUNS ROUGH/ROLLING IDLE
DESCRIPTION
•  The engine speed fluctuates between the specified idle speed and lower speed and the engine shakes excessively.
•  The idle speed is too slow and the engine shakes excessively.
POSSIBLE CAUSE
•  Air leakage from intake-air system parts
•  A/C system operation is improper
•  Spark leakage from high-tension leads
•  Purge solenoid valve malfunction
•  IAC valve improper operation
•  Low engine compression
•  Erratic signal from CMP 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
•  Fuel leakage from fuel injector
•  Fuel injector clogging
•  Engine overheating
•  Vacuum leakage
•  Pressure regulator control (PRC) system malfunction
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 the “BEFORE SERVICE PRECAUTION” and “AFTER SERVICE PRECAUTION” described in this manual.
Caution
•  If there is foreign material on the connecting area of the quick release connector, it might damage the connector or fuel pipe. To prevent this, disconnect the connector and clean the connecting area before connecting.

Diagnostic procedure

STEP

INSPECTION

RESULTS

ACTION
1
Verify the following:
•  External furl shut off or accessory
•  Fuel quality (such as proper octane, contamination, winter/summer blend)
•  No air leakage from intake-air system
•  Proper sealing of intake manifold and components attached to intake manifold: 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 M-MDS to the DLC-2.
Turn the ignition switch to the ON position (Engine off).
Retrieve any DTCs.
Are there any DTCs displayed?
Yes
DTC is displayed:
•  Go to appropriate the DTC inspection.
No
No DTC is displayed:
•  Inspect instrument cluster operation.
3
Is the engine overheating?
Yes
Go to symptom troubleshooting “No.16 Cooling system concerns - Overheating”.
(See NO.16 COOLING SYSTEM CONCERNS-OVERHEATING [F2].)
No
Go to the next step.
4
Note
•  Following test is for engine running rough idle with the A/C on concerns. If other symptoms exist, go to the next step.
Connect pressure gauge to the A/C low and high pressure side lines.
Start the engine and idle it.
Turn the A/C switch on.
Measure low side and high side pressures.
Are pressures within specifications?
(See REFRIGERANT PRESSURE CHECK.)
Yes
Go to the next step.
No
If the A/C is always on, go to symptom troubleshooting “No.23 A/C is always on or A/C compressor runs continuously”.
(See NO.23 A/C IS ALWAYS ON/A/C COMPRESSOR RUNS CONTINUOUSLY [F2].)
For other symptoms, inspect following:
•  Refrigerant charging amount
5
Note
•  Following test is for engine running rough with the P/S on. If other symptoms exist, go to the next step.
Start the engine and idle it.
Access PSP PID.
Inspect if PSP PID is on while turning steering wheel right to left.
Is PSP PID normal?
Yes
Inspect the PSP switch operation and wiring harness between the PSP switch connector and the PCM connector terminal 1P.
No
Go to the next step.
6
Visually inspect the CMP sensor.
Is CMP sensor normal?
Yes
Go to the next step.
No
Replace the malfunctioning part.
7
Inspect for cracks on high-tension leads.
Are there any cracks on high-tension leads?
Yes
Repair suspected high-tension leads.
No
Go to the next step.
8
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 clogged the 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 engine speed drop or the engine stall?
Yes
Go to the next step.
No
Inspect the IAC valve and wiring harness.
(See IDLE AIR CONTROL (IAC) VALVE INSPECTION [F2].)
10
Install fuel pressure gauge between the fuel main pipe and the fuel distributor.
Start the engine and idle it.
Measure fuel line pressure during idle.
Is fuel line pressure correct during idle?
(See FUEL PUMP UNIT INSPECTION [F2].)
Yes
Go to the next step.
No
Zero or low:
Inspect the fuel pump circuit.
Inspect for the open fuel pump relief valve.
Inspect for the fuel leakage inside pressure regulator.
Inspect for the clogged main fuel line.
High:
Inspect the pressure regulator for high pressure cause.
Inspect for the clogged fuel return line.
11
Visually inspect the fuel injector, O-ring, and fuel line for fuel leakage.
Service if necessary.
Does fuel line pressure hold after the ignition switch is turned off?
(See FUEL PUMP UNIT INSPECTION [F2].)
Yes
Go to the next step.
No
Inspect the pressure regulator diaphragm condition.
•  If condition is normal, inspect the fuel injector.
•  If condition is not normal, replace pressure regulator.
12
Connect the M-MDS to the DLC-2.
Start the engine and idle it.
Access O2S11 PID.
Is O2S11 PID normal?
•  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 the next step.
No
Inspect and repair or replace the faulty O2S, wiring harness, connector or terminal, then go to the next step.
(See OXYGEN SENSOR (O2S) INSPECTION [F2].)
13
Disconnect the vacuum hose between the purge solenoid valve and the dynamic chamber from the purge solenoid valve side.
Plug the opening end of vacuum hose.
Start the engine.
Does engine condition improve?
Yes
Inspect if the purge solenoid valve is stuck open mechanically.
Inspect EVAP control system.
(See ENGINE CONTROL SYSTEM OPERATION INSPECTION [F2].)
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
Is there restriction in exhaust system?
Yes
Inspect exhaust system.
No
Go to the next step.
16
Is engine compression correct?
(See COMPRESSION INSPECTION [F2].)
Yes
Inspect valve timing.
No
Inspect for cause.
17
•  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 the PCM.