Definition: A momentary lack of response as the accelerator is pushed down. This condition can occur at any vehicle speed. his condition is usually most pronounced when you first try to make the vehicle move, as from a stop sign. This may cause the engine to stall if the condition is severe enough.

Did you perform the 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 20

Go to Step 3

Did you perform a visual/physical check?

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Go to Step 4

Go to Symptoms for the Visual /Physical Check

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 to the different throttle positions, check the HO2S for silicon or other contaminants from the fuel or the use of the 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 ECMPCM will then reduce the amount of the 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 20

Go to Step 5

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 20

Go to Step 6

Observe the TP Signal display on the scan tool while slowly increasing throttle pedal.

Does the TP Signal display steadily increase from the closed throttle to the WOT?

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Go to Step 7

Go to DTC P0120 Throttle Position (TP) Sensor Circuit

Monitor the Long Term Fuel Trim 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 20

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 20

Go to Step 10

1. Check for a proper ignition coil output voltage with spark tester J 26792 (ST 125) by performing the following procedure:

•	Clip the spark tester J 26792 to engine ground.

•	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.

•	Disconnect the spark plug wire from the other spark plug on the same coil being tested, and ground the wire.

•	Crank the engine while observing the spark tester J 26792 . Look for a blue spark.

•	Repeat the above steps for each coil.

2. 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 20

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 20

Go to Step 12

Important: Spray the secondary ignition wires with a light mist of water in order to help locate an intermittent problem. The ignition components will arc to ground when a secondary component is malfunctioning. Refer to Ignition System Check .

1. Visually/Physically inspect the secondary ignition wires. Check the secondary ignition wires for the following conditions:

•	Check to ensure that all of the ignition wire resistance is at less than the specified value.

•	Check the ignition wires for cross firing.

•	Check the ignition wires for any arcing to ground.

•	Check the ignition wires for improper routing.

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

Was a problem found?

30Kohms

Go to Step 20

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 20

Go to Step 14

1. Check the ignition coil secondary resistance.
2. Replace any coil(s) that are not within the specified values.

Did any of the coil(s) require a replacement?

5-8Kohms

Go to Step 20

Go to Step 15

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

•

Wet plugs

•

Cracks

•	Excessive wear

•	An improper gap

•	Burned electrodes

•	Carbon tracking on the insulator

•	Heavy deposits. Refer to Ignition System Check .

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

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

Was a problem found?

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Go to Step 20

Go to Step 16

1. Check the ECMPCM grounds for being clean, tight and in the proper locations.
2. If a problem is present, repair as necessary.

Was a problem found?

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Go to Step 20

Go to Step 17

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

Was a problem found?

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Go to Step 20

Go to Step 18

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

•

Splits

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Kinks

•	Proper connections

•	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 20

Go to Step 19

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:

•	Perform a visual/physical inspection.

•	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 20

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 .