11

ENGINE STALLS/QUITS—ACCELERATION/CRUISE

ENGINE RUNS ROUGH—ACCELERATION/CRUISE

MISSES—ACCELERATION/CRUISE

BUCK/JERK—ACCELERATION/CRUISE/DECELERATION

HESITATION/STUMBLE—ACCELERATION

SURGES—ACCELERATION/CRUISE

DESCRIPTION

• Engine stops unexpectedly at the beginning of acceleration or during acceleration.

• Engine stops unexpectedly while cruising.

• Engine speed fluctuates during acceleration or cruising.

• Engine misses during acceleration or cruising.

• Vehicle bucks/jerks during acceleration, cruising, or deceleration.

• Momentary pause at beginning of acceleration or during acceleration

• Momentary minor irregularity in engine output

POSSIBLE CAUSE

• Improper A/C system operation

• Erratic signal or no signal from CMP sensor

• Air leakage from intake-air system parts

• Purge solenoid valve malfunction

• Improper operation of electronic throttle control system

• EGR valve malfunction

• Erratic signal from CKP sensor

• Low engine compression

• Vacuum leakage

• Poor fuel quality

• Main relay intermittent malfunction

• Throttle body malfunction

• Engine overheating

• Spark plug malfunction

• Improper air/fuel mixture ratio control operation

• Erratic signal to ignition coil

• Air cleaner restriction

• PCV valve malfunction

• Fuel flow into evaporative purge hose

• Improper valve timing due to jumping out timing belt

• Restriction in exhaust system

• Intermittent open or short circuit in fuel body pump circuit

• Inadequate fuel pressure

• Fuel pump mechanical malfunction

• Check valve (two-way) malfunction integrated with fuel tank

• Fuel leakage from fuel injector

• Fuel injector clogging

• Fuel line restriction or clogging

• Pressure regulator malfunction (built-in fuel pump unit)

• Erratic signal form Accelerator pedal position sensor

• Erratic signal form TP sensor

• Intermittent open or short circuit of MAF sensor, TP sensor, Accelerator pedal position sensor and VSS

• AT malfunction (AT)

• Clutch slippage (MT)

• Improper variable intake air control operation

• Loose attaching bolts or worn engine mounts

WARNING:

• 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 [LF].)

  (See AFTER SERVICE PRECAUTION [LF].)

CAUTION:

• Disconnecting/connecting quick release connector without cleaning it may 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.

STEP

INSPECTION

RESULTS

ACTION

1

Verify the following:

• Vacuum connection

• Air cleaner element

• No air leakage from intake-air system

• No restriction of intake-air system

• Proper sealing of intake manifold and components attached to intake manifold: such as EGR valve

• Ignition wiring

• Fuel quality (such as proper octane, contamination, winter/summer blend)

• Electrical connections

• 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 the appropriate DTC inspection.

(See DTC TABLE [LF].)

No

No DTC is displayed:

Go to the next step.

3

Is engine overheating?

Yes

Go to symptom troubleshooting "No.17 Cooling system concerns - Overheating".

No

Go to the next step.

4

Connect the M-MDS to the DLC-2.

Access APP1, APP2, RPM, VPWR, MAF, TP and VSS PIDs.

Drive the vehicle with monitoring PIDs.

Are PIDs within specifications?

(See PCM INSPECTION [LF].)

Yes

Go to the next step.

No

APP1, APP2 PIDs:

Inspect if output signal from accelerator pedal position sensor changes smoothly.

RPM PID:

Inspect the CKP sensor and related wiring harness for vibration or intermittent open/short circuit.

VPWR PID:

Inspect for open circuit intermittently.

MAF PID:

Inspect for open circuit of the MAF sensor and related wiring harness intermittently.

TP PID:

Inspect if output signal from TP sensor changes smoothly.

VSS PID:

Inspect for open circuit of VSS and related wiring harness intermittently.

5

Visually inspect the CKP sensor and teeth of crankshaft pulley.

Are CKP sensor and teeth of crankshaft pulley normal?

Yes

Go to the next step.

No

Replace the malfunctioning part.

6

Inspect the 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 fuel injector.

Spark plug is grayish white:

Inspect the fuel injector for clogging.

No

Install the spark plugs on original cylinders.

Go to the next step.

7

Remove and shake the PCV valve.

Does the PCV valve rattle?

Yes

Go to the next step.

No

Replace the PCV valve.

8

Perform the electronic throttle control system operation inspection.

(See ENGINE CONTROL SYSTEM OPERATION INSPECTION [LF].)

Does the electronic throttle control system function properly?

Yes

Go to the next step.

No

Repair or replace the malfunctioning part according to electronic throttle system operation inspection results.

9

Visually inspect deformed exhaust system part.

Is there any deformed exhaust system part?

Yes

Replace the suspected part.

No

Go to the next step.

10

Install fuel pressure gauge between the fuel pipe and fuel distributor.

Short check connector terminal F/P to body GND using a jumper wiring.

Turn the ignition switch to the ON position.

Is fuel line pressure correct with ignition switch to ON position?

(See FUEL LINE PRESSURE INSPECTION [LF].)

Yes

Go to the next step.

No

Zero or low:

Inspect the fuel pump relay and fuel pump circuit.

Inspect the fuel line for clogging.

If there is no malfunction, replace the fuel pump unit.

(See FUEL PUMP UNIT REMOVAL/INSTALLATION [LF].)

High:

Replace the fuel pump unit.

(See FUEL PUMP UNIT REMOVAL/INSTALLATION [LF].)

11

Visually inspect for fuel leakage at fuel injector O-ring and fuel line.

Service if necessary.

Is fuel line pressure held after ignition switch is turned off?

(See FUEL LINE PRESSURE INSPECTION [LF].)

Yes

Go to the next step.

No

Inspect the fuel injector.

If the fuel injector is normal, replace the fuel pump unit.

(See FUEL PUMP UNIT REMOVAL/INSTALLATION [LF].)

12

NOTE:

• The following test is for engine stall with the A/C on. If other symptom exists, go to the next step.

Connect a pressure gauge to A/C low and high pressure side lines.

Turn the A/C on and measure low side and high side pressure.

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.24 A/C is always on or A/C compressor runs continuously".

(See NO.24 A/C IS ALWAYS ON/A/C COMPRESSOR RUNS CONTINUOUSLY [LF].)

For other symptoms, inspect the following:

• Refrigerant charging amount

• Condenser fan operation

13

NOTE:

• The following test should be performed for symptom with cruise control ON. If other symptoms exist, go to the next step.

Inspect cruise control system.

Is cruise control system normal?

Yes

Go to the next step.

No

Repair or replace the malfunctioning part.

14

Inspect the front HO2S.

(See FRONT HEATED OXYGEN SENSOR (HO2S) INSPECTION [LF].)

Is the front HO2S normal?

Yes

Go to the next step.

No

Replace the front HO2S.

(See FRONT HEATED OXYGEN SENSOR (HO2S) REMOVAL/INSTALLATION [LF].)

15

Inspect the evaporative purge hose between the fuel tank and the purge valve.

Does fuel flow into evaporative purge hose?

Yes

Inspect the check valve (two-way).

(See FUEL TANK INSPECTION [LF].)

No

Go to the next step.

16

Disconnect the vacuum hose between the purge solenoid valve and the intake manifold from the purge solenoid valve side.

Plug opening end of vacuum hose.

Drive the vehicle.

Does the engine condition improve?

Yes

Go to the next step.

Inspect if the purge solenoid valve is stuck open mechanically.

Inspect the evaporative emission control system.

No

Go to the next step.

17

Visually inspect the CMP sensor and projections of camshaft pulley.

Are CMP sensor and projections of camshaft pulley normal?

Yes

Go to the next step.

No

Replace the malfunctioning part.

18

Inspect the EGR system.

(See ENGINE CONTROL SYSTEM OPERATION INSPECTION [LF].)

Is the EGR system normal?

Yes

Go to the next step.

No

Replace the malfunctioning part.

19

Is the engine compression correct?

Yes

Inspect the following:

• Valve timing

• Internal transaxle part (AT)

• Clutch (MT)

• EGR valve (mechanical stuck)

• Engine mounts

• Check valve (two-way)

No

Inspect for cause.

20

• Verify test results.

• If normal, return to diagnostic index to service any additional symptoms.

  (See SYMPTOM DIAGNOSTIC INDEX [LF].)

• If malfunction remains, inspect related Service Bulletins and/or On-line Repair 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.

  (See PCM REMOVAL/INSTALLATION [LF].)