Definition: Engine delivers less than expected power. Little or no increase in speed when accelerator pedal is pushed down part way.

Was the Powertrain On-Board Diagnostic (OBD) System Check performed?

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Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

1. Perform a bulletin search.
2. If a bulletin that addresses the symptom is found, correct the condition as instructed in the bulletin.

Was a bulletin found that addresses the symptom?

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Go to Step 18

Go to Step 3

Compare the vehicle performance with a similar vehicle. Both vehicle's performance should be close.

Is the vehicle performance close to similar vehicle.

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No problem found

Go to Step 4

Was visual/physical check performed?

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Go to Step 5

Go to Important Preliminary Checks

1. Remove and check air filter element for dirt, or for being restricted. Refer to Air Cleaner for On-Vehicle Service.
2. Replace air filter element if necessary.

Was a repair required?

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Go to Step 18

Go to Step 6

1. Check for low fuel pressure. Refer to Fuel System Diagnosis .
2. If a problem is found, repair as necessary.

Was a problem found?

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Go to Step 18

Go to Step 7

1. Check for Water or alcohol contaminated fuel using J 39383-A.
2. If a problem is found, repair as necessary.

Was a problem found?

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Go to Step 18

Go to Step 8

1. Using a scan tool, monitor the KS system for excessive spark retard activity. Refer to Knock Sensor (KS) System Diagnosis .
2. If a problem is found, repair as necessary.

Was a problem found?

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Go to Step 18

Go to Step 9

1. Check for proper ignition voltage output using the spark plug jumper wires J 36012 and spark tester J 26792.
2. If a problem is found, repair as necessary.

Was a problem found?

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Go to Step 18

Go to Step 10

Important: If spark plugs are gas or oil fouled, the cause of the fouling must be determined before replacing the spark plugs in order to prevent further damage.

1. Remove the spark plugs, check for wet plugs, cracks, wear, improper gap, burned electrodes, or heavy deposits.

1. If a problem is found, repair as necessary.

Was a problem found?

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Go to Step 18

Go to Step 11

1. Check the ignition coils for cracks or carbon tracking.
2. If a problem is found, repair as necessary.

Was a problem found?

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Go to Step 18

Go to Step 12

1. Check the PCM grounds for being clean, tight and in their proper locations. Refer to 8A wiring diagrams.
2. If a problem is found, repair as necessary.

Was a problem found?

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Go to Step 18

Go to Step 13

1. Check the exhaust system for possible restriction in the following areas:

•	Inspect exhaust system for damaged or collapsed pipes.

•	Inspect muffler for heat distress or possible internal failure.

•	Check for a possible plugged three-way catalytic converter by checking exhaust system back pressure. Refer to Restricted Exhaust System Check

2. f a problem is found, repair as necessary.

Was a problem found?

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Go to Step 18

Go to Step 14

1. Check for proper generator voltage output.
2. The voltage should be between the specified values.

Is the voltage between the specified values?

11-16V

Go to Step 15

Go to Section 6D

1. Check for proper A/C operation. A/C clutch should disengage at Wide Open Throttle.
2. If a problem is found, refer to Air Conditioning (A/C) Compressor Clutch Control Diagnosis for further diagnosis.

Was a problem found?

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Go to Air Conditioning (A/C) Compressor Clutch Control Diagnosis

Go to Step 16

1. Engine mechanical problem. Check for low compression, incorrect or worn camshaft, loose timing chain etc. Refer to Engine Mechanical.
2. If a problem is found, repair as necessary.

Was a problem found?

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Go to Step 18

Go to Step 17

1. Review all diagnostic procedures within this table.
2. When all procedures have been completed and no malfunctions are found, review/inspect the following items:

•	Visual/physical inspection.

•	Scan tool data.

•	All connections within a suspected circuit and/or system.

3. If a problem is found, repair as necessary.

Was a problem found?

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Go to Step 18

Check for Service Bulletins

Operate vehicle within the conditions under which the original symptom was noted.

Does the system now operate properly?

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System OK

Go to Step 2