NO.11 LACK/LOSS OF POWER (ACCELERATION/CRUISE) [G6]

11	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 • Air leakage from intake-air system parts • Purge control solenoid malfunction • Brake dragging • Erratic signal from CMP sensor • Low engine compression • Vacuum leakage • Poor fuel quality • Spark leakage from high-tension leads • Air cleaner restriction • PCV valve malfunction • Improper valve timing due to jumping out of timing chain • Restriction in exhaust system • Intermittent open or short circuit in fuel pump related circuit • Inadequate fuel pressure • Fuel pump mechanical malfunction • Fuel leakage from fuel injector • Fuel injector clogging • Intermittent open or short circuit of MAF sensor, TP sensor, IAT sensor and VSS • Clutch slippage 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. (See BEFORE REPAIR PROCEDURE [G6].) (See AFTER REPAIR PROCEDURE [G6].)

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

• Air leakage from intake-air system parts

• Purge control solenoid malfunction

• Brake dragging

• Erratic signal from CMP sensor

• Low engine compression

• Vacuum leakage

• Poor fuel quality

• Spark leakage from high-tension leads

• Air cleaner restriction

• PCV valve malfunction

• Improper valve timing due to jumping out of timing chain

• Restriction in exhaust system

• Intermittent open or short circuit in fuel pump related circuit

• Inadequate fuel pressure

• Fuel pump mechanical malfunction

• Fuel leakage from fuel injector

• Fuel injector clogging

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

• Clutch slippage

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.

(See BEFORE REPAIR PROCEDURE [G6].)

(See AFTER REPAIR PROCEDURE [G6].)

STEP	INSPECTION	RESULTS	ACTION
1	Verify the following: • Vacuum connection • Air cleaner element • 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 intake manifold; such as IAC valve • Fuel quality (such as proper octane, contamination, winter/summer blend) 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. (See DTC TABLE [G6].)
No	No DTC is displayed: • Inspect instrument cluster operation. (See INSTRUMENT CLUSTER INSPECTION.)
3	Is the engine overheating?	Yes	Go to symptom troubleshooting “No.16 Cooling system concerns - Overheating”. (See NO.16 COOLING SYSTEM CONCERNS-OVERHEATING [G6].)
No	Go to the next step.
4	Connect the M-MDS to the DLC-2. Access RPM, MAF, TP and VSS PIDs. • RPM PID • MAF PID • TP PID • VSS PID Drive vehicle while monitoring PIDs. Are PIDs within specifications? (See PCM INSPECTION [G6].)	Yes	Go to the next step.
No	RPM PID: Inspect the CMP sensor and related wiring harness for vibration and/or intermittent open/short circuit. MAF PID: Inspect for intermittent open circuit of the MAF sensor and related wiring harness. TP PID: Inspect if the TP sensor output increases smoothly. VSS PID: Inspect for intermittent open circuit of the VSS and related wiring harness.
5	Visually inspect the CMP sensor. Is CMP sensor normal?	Yes	Go to the next step.
No	Replace the malfunctioning parts.
6	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 the fuel injector for fuel injector. Spark plug is grayish white: Inspect for clogged the fuel injector.
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	Is there restriction in exhaust system?	Yes	Inspect exhaust system.
No	Go to the next step.
9	Install fuel pressure gauge between the fuel pipe and the fuel distributor. Connect jumper wire between F/P terminal at DLC in engine compartment and ground. Turn the ignition switch to the ON position. Is fuel line pressure correct with ignition switch on? (See FUEL PUMP UNIT INSPECTION [G6].)	Yes	Go to the next step.
No	Zero or low: Inspect fuel pump circuit. Inspect for open fuel pump relief valve. Inspect for fuel leakage inside pressure regulator. Inspect for clogged main fuel line. High: Inspect pressure regulator for high pressure cause. Inspect for clogged fuel return line.
10	Install vacuum gauge to intake manifold. Start engine. Does fuel pressure gauge reading increase as vacuum gauge reading decreases and/or does fuel pressure gauge reading decrease as vacuum reading increases?	Yes	Go to the next step.
No	Connect vacuum hose to pressure regulator. Start engine. Verify that fuel pressure gauge reading changes as vacuum changes. If it changes, inspect vacuum line. If it does not change, replace pressure regulator.
11	Note • Following test is for the engine stalling with the A/C on concern. If other symptoms exist, go to the next step. Connect pressure gauge to the A/C low and high side pressure lines. Turn the A/C on and 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 [G6].) For other symptoms, inspect the following: • Refrigerant charging amount
12	Inspect A/C cut-off operation. (See ENGINE CONTROL SYSTEM OPERATION INSPECTION [G6].) Does A/C cut-off function properly?	Yes	Go to the next step.
No	Inspect the A/C cut-off system components. (See ENGINE CONTROL SYSTEM OPERATION INSPECTION [G6].)
13	Disconnect the vacuum hose between the purge solenoid valve and the dynamic chamber from purge solenoid valve side. Plug opening end of vacuum hose. Drive the vehicle. Does the engine condition improve?	Yes	Inspect if the purge solenoid valve is stuck open mechanically. Inspect EVAP control system. (See ENGINE CONTROL SYSTEM OPERATION INSPECTION [G6].)
No	Go to the next step.
14	Is engine compression correct?	Yes	Inspect following: • Valve timing • Clutch • Brake system for dragging
No	Inspect for cause.
15	• Verify test results. ― If normal, return to diagnostic index to service any additional symptoms. (See ENGINE SYMPTOM TROUBLESHOOTING [G6].) ― 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. (See PCM REMOVAL/INSTALLATION [G6].)

STEP

INSPECTION

RESULTS

ACTION

Verify the following:

• Vacuum connection

• Air cleaner element

• 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 intake manifold; such as IAC valve

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

Are all items normal?

Yes

Go to the next step.

Service if necessary.

Repeat Step 1.

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.

(See DTC TABLE [G6].)

No DTC is displayed:

• Inspect instrument cluster operation.

(See INSTRUMENT CLUSTER INSPECTION.)

Is the engine overheating?

Yes

Go to symptom troubleshooting “No.16 Cooling system concerns - Overheating”.

(See NO.16 COOLING SYSTEM CONCERNS-OVERHEATING [G6].)

Go to the next step.

Connect the M-MDS to the DLC-2.

Access RPM, MAF, TP and VSS PIDs.

• RPM PID

• MAF PID

• TP PID

• VSS PID

Drive vehicle while monitoring PIDs.

Are PIDs within specifications?

(See PCM INSPECTION [G6].)

Yes

Go to the next step.

RPM PID:

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

MAF PID:

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

TP PID:

Inspect if the TP sensor output increases smoothly.

VSS PID:

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

Visually inspect the CMP sensor.

Is CMP sensor normal?

Yes

Go to the next step.

Replace the malfunctioning parts.

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 the fuel injector for fuel injector.

Spark plug is grayish white:

Inspect for clogged the fuel injector.

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.

Is there restriction in exhaust system?

Yes

Inspect exhaust system.

Go to the next step.

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

Connect jumper wire between F/P terminal at DLC in engine compartment and ground.

Turn the ignition switch to the ON position.

Is fuel line pressure correct with ignition switch on?

(See FUEL PUMP UNIT INSPECTION [G6].)

Yes

Go to the next step.

Zero or low:

Inspect fuel pump circuit.

Inspect for open fuel pump relief valve.

Inspect for fuel leakage inside pressure regulator.

Inspect for clogged main fuel line.

High:

Inspect pressure regulator for high pressure cause.

Inspect for clogged fuel return line.

Install vacuum gauge to intake manifold.

Start engine.

Does fuel pressure gauge reading increase as vacuum gauge reading decreases and/or does fuel pressure gauge reading decrease as vacuum reading increases?

Yes

Go to the next step.

Connect vacuum hose to pressure regulator.

Start engine.

Verify that fuel pressure gauge reading changes as vacuum changes.

If it changes, inspect vacuum line.

If it does not change, replace pressure regulator.

Note

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

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

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

Are pressures within specifications?

(See REFRIGERANT PRESSURE CHECK.)

Yes

Go to the next step.

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 [G6].)

For other symptoms, inspect the following:

• Refrigerant charging amount

Inspect A/C cut-off operation.

(See ENGINE CONTROL SYSTEM OPERATION INSPECTION [G6].)

Does A/C cut-off function properly?

Yes

Go to the next step.

Inspect the A/C cut-off system components.

(See ENGINE CONTROL SYSTEM OPERATION INSPECTION [G6].)

Disconnect the vacuum hose between the purge solenoid valve and the dynamic chamber from purge solenoid valve side.

Plug opening end of vacuum hose.

Drive the vehicle.

Does the engine condition improve?

Yes

Inspect if the purge solenoid valve is stuck open mechanically.

Inspect EVAP control system.

(See ENGINE CONTROL SYSTEM OPERATION INSPECTION [G6].)

Go to the next step.

Is engine compression correct?

Yes

Inspect following:

• Valve timing

• Clutch

• Brake system for dragging

Inspect for cause.

• Verify test results.

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

(See ENGINE SYMPTOM TROUBLESHOOTING [G6].)

― 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.

(See PCM REMOVAL/INSTALLATION [G6].)