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 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 16

Go to Step 3

Was visual/physical check performed?

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Go to Step 4

Go to Visual /Physical Check

1. Remove and check air filter element for dirt, or for being restricted.
2. Replace air filter element if necessary.

Was a repair required?

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Go to Step 16

Go to Step 5

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 16

Go to Step 6

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 16

Go to Step 7

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

Was a problem found?

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Go to Step 16

Go to Step 8

1. Check for proper ignition coil output voltage with spark tester J 26792 (ST 125):

•	Clip the spark tester J 26792 to engine ground.

•	Connect J 26792 to an ignition wire then ground spark plug end of ignition wire from companion cylinder. The companion cylinder is the cylinder that shares the same ignition coil.

•	Crank the engine while observing the spark tester J 26792; a crisp blue spark should be observed.

•	Repeat the above steps for each coil.

2. If adequate spark is not present at all coils, repair as necessary.

Was a problem found?

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Go to Step 16

Go to Step 9

Notice: Determine the cause of the oil or gas fouled spark plugs in order to avoid damage to the new spark plugs.

1. Remove spark plugs, check for wet plugs, cracks, wear, improper gap, burned electrodes, or heavy deposits. Refer to Electronic Ignition System.
2. If a problem is found, repair as necessary.

Was a problem found?

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Go to Step 16

Go to Step 10

1. Check 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 16

Go to Step 11

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

Was a problem found?

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Go to Step 16

Go to Step 12

1. Check exhaust system for possible restriction:

•	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 16

Go to Step 13

1. Check Torque Converter Clutch (TCC) for proper operation. Refer to 4T60-E Transaxle Diagnosis.
2. If a problem is found, repair as necessary.

Was a problem found?

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Go to Step 16

Go to Step 14

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 16

Go to Step 15

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

•	Visual/physical inspection.

•	Scan Tool data.

•	Freeze Frame data/Failure Records 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 16

Review Technical Service Bulletins

Operate the vehicle to duplicate conditions present when the original symptom was noted.

Is symptom still present?

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Go to Step 3

Repair complete