Definition: A momentary lack of response as the accelerator is pushed down. A hesitation, sag or stumble can occur at all vehicle speeds, and is usually most severe when you first try to make the vehicle move, as from a stop sign. This may cause the engine to stall if the symptom severe enough.

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

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Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

1. Perform a bulletin search.
2. If you find a bulletin that addresses the symptom, 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

Perform the careful visual/physical checks as described at the start of the Symptoms section.

Did you perform the visual/physical check?

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Go to Step 4

Go to Important Preliminary Checks

Check the TP sensor for binding or sticking. The voltage should increase at a steady rate as the throttle is moved toward a wide open throttle.

Is a problem present?

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Go to Step 16

Go to Step 5

1. Check the MAP sensor for a proper operation. Refer to Manifold Absolute Pressure Sensor Output Diagnosis .
2. If a malfunction is present, repair the malfunction.

Was a repair necessary?

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Go to Step 16

Go to Step 6

1. Check for any fouled spark plugs.
2. Replace any malfunctioning spark plugs.

Was a replacement necessary?

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Go to Step 16

Go to Step 7

1. Check the Ignition Control Module for a proper ground connection.
2. Repair the ground connection if the ground is malfunctioning.

Was a repair necessary?

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Go to Step 16

Go to Step 8

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

Was a repair necessary?

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Go to Step 16

Go to Step 9

1. Check for contaminated fuel.
2. If a problem is present, repair the problem as necessary.

Was a repair necessary?

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Go to Step 16

Go to Step 10

1. Perform the Fuel Injector Solenoid Coil Test and the Fuel Injector Balance Test .
2. If a problem is present, repair the problem as necessary.

Was a repair necessary?

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Go to Step 16

Go to Step 11

1. Check for a proper system performance. Use Table Evaporative Emission Control System Diagnosis .
2. If a problem is present, repair the problem as necessary.

Was a repair necessary?

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Go to Step 16

Go to Step 12

1. Check for a proper function of the thermostat. Also, check for the proper heat range. Refer to Engine Cooling .
2. If a problem is present, repair the problem as necessary.

Was a repair necessary?

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Go to Step 16

Go to Step 13

1. Check the generator for proper output voltage.
2. The generator output voltage should be between the specified values.

Is the voltage between the specified value?

11 V-16 V

Go to Step 14

Go to Powertrain Control Module Controlled Generator Diagnosis

1. Check the intake valves for valve deposits.
2. If deposits are present, remove the deposits as necessary.

Were there any deposits on the intake valves?

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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 are present, visually/physically inspect the following items:

•	The scan tool data

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

3. If a problem is found, repair the problem as necessary.

Was a repair necessary

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Go to Step 16

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Operate the vehicle within the conditions under which the original symptom was recorded.

Does the system now operate properly?

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System OK

Go to Step 2