Definition: Engine power variation under steady throttle or cruise. The vehicle speeds up and slows down with no change in the accelerator pedal.

Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?

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Go to Step 2

Go to the Powertrain On Board Diagnostic (OBD) System Check

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

Was a bulletin found that addresses the symptom?

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Go to Step 22

Go to Step 3

Did you perform the visual/physical check?

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Go to Step 4

Go to Symptoms for the Visual /Physical Check

Be sure that the driver understands the Transmission torque converter clutch and the A/C compressor operation as explained in the owner's manual. Inform the customer how the TCC and the A/C clutch operates.

Is the customer experiencing a normal condition?

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System OK

Go to Step 5

1. Check the Heated Oxygen Sensors (HO2S). The Heated Oxygen Sensors (HO2S) should respond quickly to the different throttle positions. If the sensors do not respond, check the HO2S for silicon or other contaminants from the fuel or the use of improper RTV sealant. The sensors may have a white powdery coating. Silicon contamination causes a high but false HO2S signal voltage (rich exhaust indication). The ECM will then reduce the amount of fuel that is delivered to the engine, causing a severe driveability problem.
2. If a problem is present, repair as necessary.

Was a repair required?

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Go to Step 22

Go to Step 6

1. Check the fuel pressure. Refer to Fuel System Diagnosis .
2. If a problem is present, repair as necessary.

Was a problem found?

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Go to Step 22

Go to Step 7

Monitor the Long Term Fuel Trim for both of the banks on the scan tool.

Is the Long Term Fuel Trim significantly in the negative range (Rich condition)?

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Go to Step 8

Go to Step 9

1. Check the items that can cause the engine to run rich.
2. If a problem is present, repair as necessary.

Was a problem found?

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Go to Step 22

Go to Step 10

1. Check the items that can cause the engine to run lean.
2. If a problem is present, repair as necessary.

Was a problem found?

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Go to Step 22

Go to Step 10

1. Check for a proper ignition coil output voltage with spark tester J 26792 (ST 125):
2. Clip the spark tester J 26792 to engine ground.
3. Connect one end of a spark plug wire to the spark tester J 26792 . Leave the other end of the spark plug wire connected to the coil being tested.
4. Disconnect the spark plug wire from the other spark plug on the same coil being tested, and ground the wire.
5. Crank the engine while observing the spark tester J 26792 . Look for a blue spark.
6. Repeat the above steps for each coil.
7. If an adequate spark is not present at all of the coils, repair as necessary.

Was a problem found?

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Go to Step 22

Go to Step 11

1. Check the primary connections at the ignition coil assembly. Refer to Electrical Diagnosis in Engine Electrical, and Troubleshooting Procedures for the proper procedure. Also, refer to Checking Terminal Contact in Engine Control Module Diagnosis .
2. If a problem is present, repair as necessary.

Was a problem found?

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Go to Step 22

Go to Step 12

Was a problem found?

7-9K ohms

2-6K ohms

Go to Step 22

Go to Step 13

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

Was a problem found?

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Go to Step 22

Go to Step 14

1. Check the ignition coil secondary resistance.
2. Replace the ignition coil assembly if any of the coils are not within the specified values.

Was a problem found?

10-14 K ohms at 20°C (68°F).

Go to Step 22

Go to Step 15

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

1. Remove the spark plugs. Check the spark plugs for the following conditions:

•

Wet plugs

•

Cracks

•	Excessive wear

•	Improper gap

•	Burned electrodes

•	Carbon tracking on the insulator

•	Heavy deposits.

2. If a problem is present, repair as necessary.

Was a problem found?

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Go to Step 22

Go to Step 16

1. Check the injector connections.
2. If any of the injector connectors are connected to an incorrect cylinder, correct as necessary.

Was a problem found?

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Go to Step 22

Go to Step 17

1. Check the ECM grounds for being clean, tight and in the proper locations. Refer to ECM Alcohol/Contaminants-in-Fuel Diagnosis the Power and Ground Check in Engine System Diagnosis.
2. If a problem is present, repair as necessary.

Was a problem found?

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Go to Step 22

Go to Step 18

1. Check the MAF sensor connections.
2. If a problem is present, replace the malfunctioning terminals as necessary. Refer to Electrical Diagnosis for the wiring repair procedures.

Was a problem found?

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Go to Step 22

Go to Step 19

1. Visually/physically check the vacuum hoses for the following conditions:

•

Splits

•

Kinks

•	Proper connections and routing as shown on the Vehicle Emission Control Information label.

2. If a problem is present, repair as necessary.

Was a problem found?

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Go to Step 22

Go to Step 20

1. Check the exhaust system for any possible restriction:

•	Inspect the exhaust system for damaged or collapsed pipes.

•	Inspect the muffler for heat distress or for possible internal failure.

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

2. If a problem is present, repair as necessary.

Was a problem found?

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Go to Step 22

Go to Step 21

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

•	The scan tool data

•	The Freeze Frame data

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

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

Was a problem found?

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Go to Step 22

Go to Step 3

Operate the vehicle under the same conditions (as closely as possible) as when the original symptom occurred.

Is the original symptom still present?

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Go to Step 3

The repair is complete. If another driveability symptom exists, refer to Symptoms .