NO.12 LACK/LOSS OF POWER-ACCELERATION/CRUISE [L8, LF, L5]

12	LACK/LOSS OF POWER — ACCELERATION/CRUISE
DESCRIPTION	Performance is poor under load (such as power down when climbing hills).
POSSIBLE CAUSE	• Improper A/C system operation • Erratic signal or no signal from CMP sensor • Air leakage from intake air system parts • Restriction in intake air system • Intake air temperature too hot • Improper variable intake air control operation • Improper variable tumble control operation • Improper operation of electronic throttle control system • Purge solenoid valve malfunction • Improper EGR valve operation • Brake dragging • Erratic signal from CKP sensor • Low engine compression • Vacuum leakage • Poor fuel quality • Erratic signal to ignition coil • Engine overheating • Throttle body malfunction • Spark plug malfunction • PCV valve malfunction • Improper valve timing due to jumping out of timing chain • Improper variable valve timing control operation (LF, L5) • Restriction in exhaust system • Intermittent open or short in fuel pump related circuit • Inadequate fuel pressure • Fuel pump mechanical malfunction • Fuel line restriction or clogging • Fuel leakage from fuel injector • Fuel injector clogging • Erratic signal from APP sensor • Erratic signal from TP sensor • Intermittent open or short circuit in MAF sensor, APP sensor, TP sensor, IAT sensor and VSS • ATX malfunction (ATX) • Clutch slippage (MTX) Warning The following troubleshooting flow chart contains the fuel system diagnosis and repair procedures. Read the following warnings before servicing the fuel system: • 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 [L8, LF, L5].) (See AFTER SERVICE PRECAUTION [L8, LF, L5].) Caution • Disconnecting/connecting the quick release connector without cleaning it may cause damage to the fuel pipe and the quick release connector. Always clean the quick release connector joint area before disconnecting/connecting, and make sure that it is free of foreign material.

LACK/LOSS OF POWER — ACCELERATION/CRUISE

DESCRIPTION

Performance is poor under load (such as power down when climbing hills).

POSSIBLE CAUSE

• Improper A/C system operation

• Erratic signal or no signal from CMP sensor

• Air leakage from intake air system parts

• Restriction in intake air system

• Intake air temperature too hot

• Improper variable intake air control operation

• Improper variable tumble control operation

• Improper operation of electronic throttle control system

• Purge solenoid valve malfunction

• Improper EGR valve operation

• Brake dragging

• Erratic signal from CKP sensor

• Low engine compression

• Vacuum leakage

• Poor fuel quality

• Erratic signal to ignition coil

• Engine overheating

• Throttle body malfunction

• Spark plug malfunction

• PCV valve malfunction

• Improper valve timing due to jumping out of timing chain

• Improper variable valve timing control operation (LF, L5)

• Restriction in exhaust system

• Intermittent open or short in fuel pump related circuit

• Inadequate fuel pressure

• Fuel pump mechanical malfunction

• Fuel line restriction or clogging

• Fuel leakage from fuel injector

• Fuel injector clogging

• Erratic signal from APP sensor

• Erratic signal from TP sensor

• Intermittent open or short circuit in MAF sensor, APP sensor, TP sensor, IAT sensor and VSS

• ATX malfunction (ATX)

• Clutch slippage (MTX)

Warning

The following troubleshooting flow chart contains the fuel system diagnosis and repair procedures. Read the following warnings before servicing the fuel system:

• 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 [L8, LF, L5].)

(See AFTER SERVICE PRECAUTION [L8, LF, L5].)

Caution

• Disconnecting/connecting the quick release connector without cleaning it may cause damage to the fuel pipe and the quick release connector. Always clean the 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 • Restriction in the intake air system (such as the air cleaner element, fresh air duct) • No air leakage from the intake air system • No restriction of the intake air system • Proper sealing of the intake manifold and components attached to the intake manifold; such as the EGR valve • Fuel quality (such as proper octane, contamination, winter/summer blend) Are all the items normal?	Yes	Go to the next step.
No	Service if necessary. Repeat Step 1.
2	Connect the M-MDS to the DLC-2. Switch the ignition to ON (Engine off). Retrieve any DTCs. Are there any DTCs displayed?	Yes	DTC is displayed: Go to the appropriate DTC inspection. (See DTC TABLE [L8, LF, L5].)
No	No DTC is displayed: Go to the next step.
3	Is the engine overheating?	Yes	Go to the symptom troubleshooting "No.17 Cooling system concerns - Overheating". (See NO.17 COOLING SYSTEM CONCERNS-OVERHEATING [L8, LF, L5].)
No	Go to the next step.
4	Connect the M-MDS to the DLC-2. Access the APP1, APP2, RPM, MAF, TP_REL, IAT and VSS PIDs. Drive the vehicle while monitoring PIDs. Are the PIDs within specifications? (See PCM INSPECTION [L8, LF, L5].)	Yes	Go to the next step.
No	APP1, APP2 PIDs: Inspect if the output signal APP sensor changes smoothly. RPM PID: Inspect the CKP sensor and the related wiring harness for vibration or intermittent open/short circuit or both. MAF PID: Inspect for an intermittent open circuit of MAF sensor and the related wiring harness. TP_REL PID: Inspect if the output signal TP sensor changes smoothly. IAT PID: Inspect for air suction in the intake air system. If normal, inspect for an intermittent short circuit in the IAT sensor and related wiring harnesses. VSS PID: Inspect for an intermittent open circuit in the VSS and related wiring harness.
5	Visually inspect the CKP sensor and teeth of the crankshaft pulley. (See CRANKSHAFT POSITION (CKP) SENSOR INSPECTION [L8, LF, L5].) Are the CKP sensor and the teeth of the crankshaft pulley normal?	Yes	Go to the next step.
No	Replace the malfunctioning part.
6	Inspect the spark plug condition. (See SPARK PLUG INSPECTION [L8, LF, L5].) Are the spark plugs wet, covered with carbon or grayish white?	Yes	Spark plug is wet or covered with carbon: Inspect the fuel injector for fuel leakage. Inspect spark plug and high-tension lead. 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. (See POSITIVE CRANKCASE VENTILATION (PCV) VALVE REMOVAL/INSTALLATION [L8, LF, L5].)
8	Perform electronic throttle control system operation inspection. (See ENGINE CONTROL SYSTEM OPERATION INSPECTION [L8, LF, L5].) Does the electronic throttle control system function properly?	Yes	Go to the next step.
No	Repair or replace the malfunctioning part according to the electronic throttle control system operation inspection results.
9	Visually inspect for deformed exhaust system parts. Are there any deformed exhaust system parts?	Yes	Replace the suspected part.
No	Go to the next step.
10	Inspect the fuel line pressure. (See FUEL LINE PRESSURE INSPECTION [L8, LF, L5].) Is the fuel line pressure correct?	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 [L8, LF, L5].) High: Replace the fuel pump unit. (See FUEL PUMP UNIT REMOVAL/INSTALLATION [L8, LF, L5].)
11	Inspect the variable tumble control operation. (See ENGINE CONTROL SYSTEM OPERATION INSPECTION [L8, LF, L5].) Does the variable tumble control function properly?	Yes	Go to the next step.
No	Repair or replace the malfunctioning part.
12	Inspect the variable intake air control operation. (See ENGINE CONTROL SYSTEM OPERATION INSPECTION [L8, LF, L5].) Does the VIS function properly?	Yes	Go to the next step.
No	Repair or replace the malfunctioning part.
13	Note • The following test is for an engine stalling with the A/C on concern. If other symptoms exist, go to the next step. Connect the pressure gauge to the A/C low and high side pressure lines. Turn the A/C on and measure the low side and high side pressures. Are the pressures within specifications? (See REFRIGERANT PRESSURE CHECK.)	Yes	Go to the next step.
No	If the A/C is always on, go to the symptom troubleshooting "No.24 A/C is always on or A/C compressor runs continuously". (See NO.24 A/C IS ALWAYS ON OR A/C COMPRESSOR RUNS CONTINUOUSLY [L8, LF, L5].) For other symptoms, inspect the following: • Refrigerant charging amount • Condenser fan operation
14	Inspect the A/C cut‐off operation. (See ENGINE CONTROL SYSTEM OPERATION INSPECTION [L8, LF, L5].) Does the A/C cut-off function properly?	Yes	Go to the next step.
No	Inspect the A/C cut‐off system components.
15	Disconnect the vacuum hose between the purge solenoid valve and the intake manifold from the purge solenoid valve side. Plug the open end of the vacuum hose. Drive the vehicle. Does the engine condition improve?	Yes	Inspect if the purge solenoid valve is stuck open mechanically. Inspect the evaporative emission control system.
No	Go to the next step.
16	Visually inspect the CMP sensor and teeth of the camshaft. (See CAMSHAFT POSITION (CMP) SENSOR INSPECTION [L8, LF, L5].) Are the CMP sensor and teeth of the camshaft normal?	Yes	Go to the next step.
No	Replace the malfunctioning part.
17	Inspect EGR system. (See ENGINE CONTROL SYSTEM OPERATION INSPECTION [L8, LF, L5].) Is the EGR system normal?	Yes	Go to the next step. (LF, L5) Go to Step 19. (L8)
No	Replace the malfunctioning part according to the EGR control system operation inspection results.
18	Inspect the variable valve timing control system operation. (See ENGINE CONTROL SYSTEM OPERATION INSPECTION [L8, LF, L5].) Does the variable valve timing control system function properly?	Yes	Go to the next step.
No	Repair or replace the malfunctioning part according to the variable valve timing control system inspection results.
19	Is the engine compression correct? (See COMPRESSION INSPECTION [L8, LF, L5].)	Yes	Inspect the following: • Valve timing • Internal transaxle components (ATX) • Clutch (MTX) • Brake system for dragging
No	Inspect for cause.
20	• Verify test results. ― If normal, return to the diagnostic index to service any additional symptoms. (See SYMPTOM DIAGNOSTIC INDEX [L8, LF, L5].) ― If the malfunction remains, inspect the related Service Information and perform repair or diagnosis. • If the vehicle is repaired, troubleshooting is completed. • If the vehicle is not repaired or additional diagnostic information is not available, replace the PCM. (See PCM REMOVAL/INSTALLATION [L8, LF, L5].)

STEP

INSPECTION

RESULTS

ACTION

Verify the following:

• Vacuum connection

• Restriction in the intake air system (such as the air cleaner element, fresh air duct)

• No air leakage from the intake air system

• No restriction of the intake air system

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

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

Are all the items normal?

Yes

Go to the next step.

Service if necessary.

Repeat Step 1.

Connect the M-MDS to the DLC-2.

Switch the ignition to ON (Engine off).

Retrieve any DTCs.

Are there any DTCs displayed?

Yes

DTC is displayed:

Go to the appropriate DTC inspection.

(See DTC TABLE [L8, LF, L5].)

No DTC is displayed:

Go to the next step.

Is the engine overheating?

Yes

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

(See NO.17 COOLING SYSTEM CONCERNS-OVERHEATING [L8, LF, L5].)

Go to the next step.

Connect the M-MDS to the DLC-2.

Access the APP1, APP2, RPM, MAF, TP_REL, IAT and VSS PIDs.

Drive the vehicle while monitoring PIDs.

Are the PIDs within specifications?

(See PCM INSPECTION [L8, LF, L5].)

Yes

Go to the next step.

APP1, APP2 PIDs:

Inspect if the output signal APP sensor changes smoothly.

RPM PID:

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

MAF PID:

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

TP_REL PID:

Inspect if the output signal TP sensor changes smoothly.

IAT PID:

Inspect for air suction in the intake air system.

If normal, inspect for an intermittent short circuit in the IAT sensor and related wiring harnesses.

VSS PID:

Inspect for an intermittent open circuit in the VSS and related wiring harness.

Visually inspect the CKP sensor and teeth of the crankshaft pulley.

(See CRANKSHAFT POSITION (CKP) SENSOR INSPECTION [L8, LF, L5].)

Are the CKP sensor and the teeth of the crankshaft pulley normal?

Yes

Go to the next step.

Replace the malfunctioning part.

Inspect the spark plug condition.

(See SPARK PLUG INSPECTION [L8, LF, L5].)

Are the spark plugs wet, covered with carbon or grayish white?

Yes

Spark plug is wet or covered with carbon:

Inspect the fuel injector for fuel leakage.

Inspect spark plug and high-tension lead.

Spark plug is grayish white:

Inspect the fuel injector for clogging.

Install the spark plugs on original cylinders.

Go to the next step.

Remove and shake the PCV valve.

Does the PCV valve rattle?

Yes

Go to the next step.

Replace the PCV valve.

(See POSITIVE CRANKCASE VENTILATION (PCV) VALVE REMOVAL/INSTALLATION [L8, LF, L5].)

Perform electronic throttle control system operation inspection.

(See ENGINE CONTROL SYSTEM OPERATION INSPECTION [L8, LF, L5].)

Does the electronic throttle control system function properly?

Yes

Go to the next step.

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

Visually inspect for deformed exhaust system parts.

Are there any deformed exhaust system parts?

Yes

Replace the suspected part.

Go to the next step.

Inspect the fuel line pressure.

(See FUEL LINE PRESSURE INSPECTION [L8, LF, L5].)

Is the fuel line pressure correct?

Yes

Go to the next step.

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 [L8, LF, L5].)

High:

Replace the fuel pump unit.

(See FUEL PUMP UNIT REMOVAL/INSTALLATION [L8, LF, L5].)

Inspect the variable tumble control operation.

(See ENGINE CONTROL SYSTEM OPERATION INSPECTION [L8, LF, L5].)

Does the variable tumble control function properly?

Yes

Go to the next step.

Repair or replace the malfunctioning part.

Inspect the variable intake air control operation.

(See ENGINE CONTROL SYSTEM OPERATION INSPECTION [L8, LF, L5].)

Does the VIS function properly?

Yes

Go to the next step.

Repair or replace the malfunctioning part.

Note

• The following test is for an engine stalling with the A/C on concern. If other symptoms exist, go to the next step.

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

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

Are the pressures within specifications?

(See REFRIGERANT PRESSURE CHECK.)

Yes

Go to the next step.

If the A/C is always on, go to the symptom troubleshooting "No.24 A/C is always on or A/C compressor runs continuously".

(See NO.24 A/C IS ALWAYS ON OR A/C COMPRESSOR RUNS CONTINUOUSLY [L8, LF, L5].)

For other symptoms, inspect the following:

• Refrigerant charging amount

• Condenser fan operation

Inspect the A/C cut‐off operation.

(See ENGINE CONTROL SYSTEM OPERATION INSPECTION [L8, LF, L5].)

Does the A/C cut-off function properly?

Yes

Go to the next step.

Inspect the A/C cut‐off system components.

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

Plug the open end of the vacuum hose.

Drive the vehicle.

Does the engine condition improve?

Yes

Inspect if the purge solenoid valve is stuck open mechanically.

Inspect the evaporative emission control system.

Go to the next step.

Visually inspect the CMP sensor and teeth of the camshaft.

(See CAMSHAFT POSITION (CMP) SENSOR INSPECTION [L8, LF, L5].)

Are the CMP sensor and teeth of the camshaft normal?

Yes

Go to the next step.

Replace the malfunctioning part.

Inspect EGR system.

(See ENGINE CONTROL SYSTEM OPERATION INSPECTION [L8, LF, L5].)

Is the EGR system normal?

Yes

Go to the next step. (LF, L5)

Go to Step 19. (L8)

Replace the malfunctioning part according to the EGR control system operation inspection results.

Inspect the variable valve timing control system operation.

(See ENGINE CONTROL SYSTEM OPERATION INSPECTION [L8, LF, L5].)

Does the variable valve timing control system function properly?

Yes

Go to the next step.

Repair or replace the malfunctioning part according to the variable valve timing control system inspection results.

Is the engine compression correct?

(See COMPRESSION INSPECTION [L8, LF, L5].)

Yes

Inspect the following:

• Valve timing

• Internal transaxle components (ATX)

• Clutch (MTX)

• Brake system for dragging

Inspect for cause.

• Verify test results.

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

(See SYMPTOM DIAGNOSTIC INDEX [L8, LF, L5].)

― If the malfunction remains, inspect the related Service Information and perform repair or diagnosis.

• If the vehicle is repaired, troubleshooting is completed.

• If the vehicle is not repaired or additional diagnostic information is not available, replace the PCM.

(See PCM REMOVAL/INSTALLATION [L8, LF, L5].)