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.

Did you find a bulletin that addresses the symptom?

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Go to Step 16

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

1. Inspect the heated oxygen sensors (HO2S). The 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 RTV sealant.
2. If a problem is present, repair as necessary.

Did you make a repair?

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Go to Step 16

Go to Step 5

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

Did you find a problem?

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Go to Step 16

Go to Step 6

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 7

Go to Step 8

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

Did you find a problem?

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Go to Step 16

Go to Step 9

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

Did you find a problem?

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Go to Step 16

Go to Step 9

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

Did you find a problem?

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Go to Step 16

Go to Step 10

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

Did you find a problem?

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Go to Step 16

Go to Step 11

1. Check the ECM grounds for being clean, tight and in the proper locations. Refer to Engine Control Module Diagnosis .
2. If a problem is present, repair as necessary.

Did you find a problem?

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Go to Step 16

Go to Step 12

1. Check the MAF sensor.
2. If a problem is present, replace the malfunctioning terminals as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find a problem?

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Go to Step 16

Go to Step 13

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.

Did you find a problem?

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Go to Step 16

Go to Step 14

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.

Did you find a problem?

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Go to Step 16

Go to Step 15

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.

Did you find a problem?

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Go to Step 16

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

Go to Step 17

Are any other driveability symptoms present?

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Go to Symptoms

System OK