NO.12 LACK/LOSS OF POWER-ACCELERATION/CRUISE [MZI-3.7]
id0103d2804800
12 |
LACK/LOSS OF POWER—ACCELERATION/CRUISE |
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DESCRIPTION
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Performance is poor under load (such as power down when climbing hills).
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POSSIBLE CAUSE
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• 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 operation of electronic throttle control system
• Purge control solenoid malfunction
• 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
• 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 accelerator pedal position sensor
• Erratic signal from TP sensor
• Intermittent open or short circuit in MAF sensor, Accelerator pedal position sensor, TP sensor, IAT sensor and VSS
• ATX malfunction
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Diagnostic procedure
STEP |
INSPECTION |
RESULTS |
ACTION |
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1
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Verify the following:
• Vacuum connection
• Restriction in intake-air system (such as air cleaner element, fresh air duct)
• No air leakage from intake-air system
• No restriction of intake-air system
• Proper sealing of intake manifold and components attached to intake manifold
• Fuel quality (such as proper octane, contamination, winter/summer blend)
Are all items normal?
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Yes
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Go to the next step.
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No
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Service if necessary.
Repeat Step 1.
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2
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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?
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Yes
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DTC is displayed:
Go to the appropriate DTC inspection.
(See DTC TABLE [MZI-3.7].)
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No
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No DTC is displayed:
Go to the next step.
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3
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Is the engine overheating?
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Yes
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Go to symptom troubleshooting “No.17 Cooling system concerns-Overheating”.
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No
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Go to the next step.
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4
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Connect the M-MDS to the DLC-2.
Access APP1, APP2, APP3, RPM, MAF, TP1, TP2, IAT and VSS PIDs.
Drive vehicle while monitoring PIDs.
Are PIDs within specifications?
(See PCM INSPECTION [MZI-3.7].)
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Yes
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Go to the next step.
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No
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APP1, APP2, APP3 PIDs:
Inspect if output signal accelerator pedal position sensor changes smoothly.
RPM PID:
Inspect CKP sensor and related wiring harness for vibration or intermittent open/short circuit or both.
MAF PID:
Inspect for intermittent open circuit of MAF sensor and related wiring harness.
TP1, TP2 PID:
Inspect if output signal TP sensor changes smoothly.
IAT PID:
Inspect for air suction in intake-air system.
If normal, inspect intermittent short circuit of IAT sensor and related wiring harnesses.
VSS PID:
Inspect for intermittent open circuit of VSS and related wiring harness.
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5
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Visually inspect the CKP sensor and teeth of crankshaft pulley.
Are the CKP sensor and teeth of crankshaft pulley normal?
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Yes
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Go to the next step.
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No
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Replace the malfunctioning part.
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6
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Inspect the spark plug condition.
Is spark plug wet, covered with carbon or grayish white?
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Yes
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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.
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No
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Install the spark plugs on original cylinders.
Go to the next step.
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7
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Remove and shake the PCV valve.
Does the PCV valve rattle?
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Yes
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Go to the next step.
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No
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Replace PCV valve.
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8
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Perform electronic throttle control system operation inspection.
Does electronic throttle control system function properly?
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Yes
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Go to the next step.
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No
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Repair or replace the malfunctioning part according to electronic throttle control system operation inspection results.
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9
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visually inspect deformed exhaust system part.
Is there any deformed exhaust system part?
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Yes
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Replace the suspected part.
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No
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Go to the next step.
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10
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Inspect the fuel line pressure.
Is the fuel line pressure correct?
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Yes
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Go to the next step.
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No
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Repair or replace the malfunctioning part.
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11
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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.)
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Yes
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Go to the next step.
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No
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If A/C is always on, go to symptom troubleshooting “No.24 A/C is always on or A/C compressor runs continuously”.
For other symptoms, inspect the following:
• Refrigerant charging amount
• Condenser fan operation
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12
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Inspect for A/C cut‐off operation.
Does the A/C cut-off function properly?
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Yes
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Go to the next step.
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No
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Inspect A/C cut‐off system components.
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13
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Disconnect the vacuum hose between the purge solenoid valve and the intake manifold from purge solenoid valve side.
Plug opening end of vacuum hose.
Drive the vehicle.
Does the engine condition improve?
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Yes
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Inspect if purge solenoid valve is stuck open mechanically.
Inspect the evaporative emission control system.
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No
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Go to the next step.
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14
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Visually inspect the CMP sensor and projections of camshaft pulley.
Are the CMP sensor and projections of camshaft pulley normal?
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Yes
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Go to the next step.
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No
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Replace the malfunctioning part.
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15
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Inspect the variable valve timing control system operation.
Does the variable valve timing control system function properly?
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Yes
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Go to the next step.
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No
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Repair or replace the malfunctioning part according to variable valve timing control system inspection results.
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16
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Is the engine compression correct?
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Yes
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Inspect the following:
• Valve timing
• Internal transaxle components
• Brake system for dragging
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No
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Inspect for cause.
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17
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• Verify test results.
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