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 Element 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 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

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

Notice: If spark plugs are gas or oil fouled, determime the cause of the fouling before replacing the spark plugs in order to avoid damage to the new spark plugs.

2. 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 Section 8A wiring diagrams.
2. If a problem is found, repair as necessary.

Was a problem found?

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. If 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?

11-16 V

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