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Home >> Pontiac >> 2007 >> Vibe Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System & Fuel System - DTC P0134 To DTC P0451 >> DTC P0301-P0304 >> Test Description

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. 1:  The Diagnostic System Check - Vehicle prompts the technician to complete some basic checks and store the Freeze Frame data on the scan tool, if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.
  2. 2:  This step verifies whether the misfire is present. The scan tool will display increasing counts in the Misfire Current Cyl. # parameter of the misfiring cylinder when a misfire is occurring.
  3. 3:  This step checks whether the MIL is the result of a hard failure or an intermittent condition. Operating the vehicle in check mode enhances the diagnostic capabilities of the PCM. The scan tool will display increasing counts in the Misfire Current Cyl. # data parameter of the cylinder that is experiencing a misfire.
  4. 4:  Fault not present indicates that the condition that caused the DTC P0301-P0304 to set is intermittent and not currently present. If no other DTCs are stored, refer to Diagnostic Aids for additional information on diagnosing an intermittent DTC P0301-P0304.
  5. 5:  This step is to verify if the misfire is caused by a fault in the ignition system.
  6. 13:  Contaminants in the fuel, such as alcohol or water, can create a misfire condition.
  7. 14:  A vacuum leak can cause a lean misfire condition.
DTC P0301-P0304

Step Action Values Yes No
Schematic Reference: Engine Controls Schematics
Connector End View Reference: Powertrain Control Module Connector End Views or Engine Controls Connector End Views
1  Did you perform the Diagnostic System Check - Vehicle? - Go to Step 2  Go to Diagnostic System Check - Vehicle
2 
  1. Install a scan tool.
  2. Start the engine.
  3. Monitor the Misfire Current Cyl. # data parameter for all engine cylinders on the scan tool.
Does the scan tool indicate a misfire in any cylinder?		 - Go to Step 5  Go to Step 3 
3 
  1. Perform the scan tool Clear DTC Information function.
  2. Place the vehicle into Check mode, using the scan tool. Refer to Service Bay Test .
  3. Operate the vehicle within the Freeze Frame conditions as specified.
  4. Monitor the Misfire Current Cyl. # data parameters on the scan tool.
Is a cylinder specific misfire DTC P0301-P0304 set or does the scan tool indicate a misfire in any cylinder?		 - Go to Step 5  Go to Step 4 
4  The fault is not present.
Are there any DTCs stored that have not been diagnosed?		 - Go to Diagnostic Trouble Code (DTC) List - Vehicle Go to Diagnostic Aids
5  Is a DTC P0351, P0352, P0353, or P0354 present? - Go to DTC P0351-P0354  Go to Step 6 
6
  1. Disconnect the ignition coil of the misfiring cylinder.
  2. Remove the ignition coil of the misfiring cylinder. Refer to Ignition Coil Replacement .
  3. Connect the electrical connector of the removed ignition coil.
  4. Install a J 26792  Spark Tester or an equivalent at the end of the spark plug boot of the removed ignition coil. See Special Tools .
  5. Crank the engine while observing the J 26792  . See Special Tools .
  6. A crisp, blue spark should be observed.
Was a crisp, blue spark present on every engine revolution?		 - Go to Step 8  Go to Step 7 
7
  1. Turn OFF the ignition.
  2. Exchange the ignition coil. Replace the ignition coil of the suspected faulty cylinder with an ignition coil from a normally operating cylinder.
  3. Install the J 26792  or an equivalent at the end of the spark plug boot of the ignition coil. See Special Tools .
  4. Test for spark as performed in step 6.
Did the test indicate a crisp, blue spark while cranking the engine?		 - Go to Step 15  Go to Electronic Ignition (EI) System Diagnosis
8
  1. Perform a visual and physical inspection of the ignition coil boot for the following conditions:
    • Water intrusion or moisture
    • A corroded or damaged electrical terminal
    • Carbon tracking
  2. Repair the condition or replace the ignition coil or spark plug as necessary. Refer to Ignition Coil Replacement or Spark Plug Replacement .
Was a repair necessary?		 - Go to Step 17  Go to Step 9 
9
  1. Remove the spark plug from the misfiring cylinders. Refer to Spark Plug Replacement .
  2. Inspect the spark plugs for correct operation and good performance. Refer to Spark Plug Inspection .
  3. Repair or replace the spark plug as necessary. Refer to Spark Plug Replacement .
Was a faulty spark plug condition found and repaired?		 - Go to Step 17  Go to Step 10 
10
  1. Turn OFF the engine.
  2. Disconnect the fuel injector of each misfiring cylinder.
  3. Install a J 34730-2B  Fuel Injector Test Lamp or an equivalent into the fuel injector harness connector of a misfiring cylinder. See Special Tools .
  4. Test the fuel injector circuit by observing the test lamp while cranking the engine.
  5. Repeat the action in step 3 and the test in step 4 for each misfiring cylinder.
Did the fuel injector test lamp blink for every test while cranking the engine?		 - Go to Step 11  Go to Fuel Injector Circuit Diagnosis
11 Perform the Fuel Injector Coil Test and the Fuel Injector Balance Test procedures. Refer to Fuel Injector Solenoid Coil Test - Engine Coolant Temperature Between 10-35 Degrees C (50-95 Degrees F) and Fuel Injector Balance Test with Special Tool .
Did any fuel injectors require replacement?		 - Go to Step 17  Go to Step 12 
12
  1. Turn OFF the ignition.
  2. Relieve the fuel pressure. Refer to Fuel Pressure Relief .
  3. Install a fuel pressure gage. Refer to Fuel Pressure Gage Installation and Removal .
  4. Install a scan tool.
  5. Turn ON the ignition, with the engine OFF.
  6. Select Fuel Pump in the Engine Output Controls menu of the scan tool.
  7. Turn ON the fuel pump, using the scan tool.
  8. Observe the fuel pressure indicated by the fuel pressure gage with the fuel pump running.
Is the fuel pressure within the specified range?		 301-347 kPa (44-50 psi) Go to Step 13  Go to Fuel System Diagnosis
13 
  1. Check a fuel sample for the following concerns:
  2. Replace the fuel, as necessary. Refer to Fuel System Cleaning .
Was a repair necessary?		 - Go to Step 17  Go to Step 14 
14 
  1. Visually and physically inspect the following for vacuum leaks:
    • The intake manifold gasket
    • The vacuum lines, hoses, and fittings
  2. Inspect for incorrect vacuum hose routing.
  3. Repair as necessary.
  4. Inspect the positive crankcase ventilation (PCV) system for an incorrectly operating or leaking PCV valve.
  5. Replace the PCV valve, as necessary.
Did you replace a part or perform a repair?		 - Go to Step 17  Go to Step 16 
15 Replace the faulty ignition coil. Refer to Ignition Coil Replacement .
Is the action complete?		 - Go to Step 17  -
16
  1. Check for the following engine mechanical conditions:
    • A worn or faulty camshaft
    • A leaky or sticky valve
    • Excessive valve deposits
    • Weak valve springs
    • A faulty valve lifter
    • An intake manifold runner leak or obstruction
    • Broken or worn piston rings
    • A leaking head gasket
  2. Repair as necessary. Refer to Diagnostic Starting Point - Engine Mechanical .
Was a basic engine mechanical concern found and repaired?		 - Go to Step 17  Go to Diagnostic Aids
17
  1. Perform the scan tool Clear DTC Information function.
  2. Operate the vehicle within the Freeze Frame conditions that set the DTC.
  3. Monitor the Misfire Current Cyl. # data parameters on the scan tool.
Did a DTC set or did the scan tool indicate a misfire in any cylinder?		 - Go to Diagnostic Trouble Code (DTC) List - Vehicle System OK
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