DEFINITION: A steady pulsation or jerking that follows the engine speed that is usually more pronounced as the engine load increases.

Did you perform the 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 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 11

Go to Step 3

Did you perform a visual/physical check?

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Go to Step 4

Go to Symptoms

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

Did you find a problem?

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Go to Step 18

Go to Step 5

Observe 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 6

Go to Step 7

1. Check the conditions 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 18

Go to Step 9

Is the Long Term Fuel Trim significantly in the positive range (Lean condition)?

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Go to Step 8

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 18

Go to Step 9

Check for an incorrect idle speed. Before checking, make sure that the following conditions are met:

Is the long air trim skewed excessively positive or negative/

90°-95° C (194°-203° F)

Go to Step 10

Go to Step 11

1. Visually/physically inspect for the following conditions:

•	Restrictions in the air intake system such as:

-	A possible collapsed air intake duct

-	A restricted air filter element

-	Any foreign objects that may be blocking the air intake system

•	Incorrect throttle body condition such as the following:

-	An incorrectly installed or malfunctioning crankcase ventilation valve

-	A disconnected brake booster hose

-	Either of these conditions can cause a large vacuum leak.

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

Did you find a problem?

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Go to Step 18

Go to Step 8

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

Did you find a problem?

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Go to Step 19

Go to Step 12

1. Check for any fuel in the pressure regulator vacuum hose.
2. Replace the fuel pressure regulator assembly if there is any fuel present. Refer to Fuel Injector and Fuel Rail Replacement .
3. If a problem is present, repair as necessary.

Did you find a problem?

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Go to Step 19

Go to Step 13

1. Check the primary 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 19

Go to Step 14

Use a scan tool in order to monitor the throttle position (TP) signal with the engine idling.

Is the TP signal at the specified value and steady?

0%

Go to Step 15

Go to DTC P1220 Throttle Position (TP) Sensor 2 Circuit

1. Verify that the crankcase ventilation valve is operating properly.
2. If a problem is present, repair as necessary.

Did you find a problem?

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Go to Step 19

Go to Step 16

1. Using a scan tool, check the transmission range switch circuits Make sure that the scan tool indicates that the vehicle is in Drive with the gear selector in Drive or Overdrive.
2. If a problem is present, repair the transmission range switch as necessary. Refer to Transmission Fluid Check .

Did you find a problem?

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Go to Step 18

Go to Step 17

1. Check for the following Engine Mechanical problems:

•	Low compression

•	Sticking valves

•	A hydraulic valve lifter problem

•	Leaking cylinder head gaskets

•	An incorrect camshaft

•	Incorrect cam timing

•	A damaged timing belt

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

Did you find a problem?

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Go to Step 19

Go to Step 18

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. Refer to Wiring Repairs in Wiring Systems.

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

Did you find a problem?

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Go to Step 19

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 20

Are any other driveability symptoms still present?

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Go to Symptoms

System OK