Diagnostic Test

1. Check for the following conditions:
   • Low engine oil level
   • Aerated engine oil
   • Incorrect engine oil filter (does not meet OEM specifications)
   • Deteriorated or dirty oil
   • Contaminated engine oil
   • Incorrect engine oil viscosity
   • Oil sludge
   • Damaged oil pump
   • Leaking oil pickup tube or seal, etc.

   Were any of the above conditions present?

   Yes 

   • Repair the engine oiling or mechanical condition.
   • Perform the PCM VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .

   No 

   • Go To  2

1. Turn the ignition off.
2. Remove the Air Cleaner Assembly from the Throttle Bodies.
3. Check for any broken components in the Throttle Bodies.
4. Check for any signs of a foreign material (ice, dirt, or excessive carbon build up) on the Throttle Plate or in the bore causing the Throttle Plate to stick.

   Were any signs of foreign material or scoring of the throttle plate or bore found?

   Yes 

   • Remove the debris if possible or replace the Throttle Body Assembly as necessary.
   • Perform the PCM VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .

   No 

   • Go To  3

1. Remove and inspect the Air Filter.

   Is the Air Filter dirty?

   Yes 

   • Replace the Air Filter.
   • Perform the PCM VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .

   No 

   • Go To  4

1. Inspect the engine for any of the following conditions:
NOTE:

Rough Idle may occur and may not be caused by component failure. Any of the following conditions can be the cause:

2. • Worn serpentine belt
   • Misalignment or binding water pump, P/S pump or A/C Compressor pulleys
   • Improper CKP, CMP, or MAP mounting
   • Poor connector/terminal to component connection for CKP Sensor, CMP Sensor, MAP Sensor, Fuel Injector, Ignition Coil, etc.
   • Vacuum leaks
   • Restriction in the air induction or exhaust system
   • Internal engine component malfunction
3. • Moisture on ignition system components
   • Insufficient fuel
   • Low quality fuel
   • Manual transmission bog
   • Towing overload

   Were any of the above issues or conditions found?

   Yes 

   • Perform the appropriate repairs.
   • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .

   No 

   • Go To  5

1. Turn the ignition on.
2. With a scan tool, read the Barometric Pressure.
   NOTE:

   The Barometric Pressure should be approximately equal to the actual barometric pressure.

3. Turn the ignition off.
4. Connect a Vacuum Gauge to a Manifold Vacuum source.
   WARNING:

   When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts or fan. Do not wear loose clothing. Failure to follow these instructions may result in possible serious or fatal injury.

5. Start the engine.
6. Allow the engine to idle.
   NOTE:

   If engine will not idle, maintain a constant rpm above idle.

7. With the scan tool, read the MAP Sensor vacuum value.
   NOTE:

   If necessary, compare the Barometric Pressure value of this vehicle to the value of a known good vehicle of a similar make and model.

   Is the scan tool reading for MAP vacuum within 1 inch of Hg of the Vacuum Gauge and is the Barometric Pressure reading of the vehicle approximately the same as actual Barometric Pressure?

   Yes 

   • Go To  6

   No 

   • Verify that there is good pin to terminal contact in the MAP Sensor and Powertrain Control Module connectors. Replace the MAP Sensor if no problems were found with the connectors.
   • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .

1. Perform the CHECKING THE FUEL DELIVERY SYSTEM test procedure. Refer to CHECKING THE FUEL DELIVERY SYSTEM (HARD START) .

   Were any problems found?

   Yes 

   • Repair as necessary in accordance with the Service Information.
   • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .

   No 

   • Go To  7

1. Perform the CHECKING THE ETHANOL LEVEL IN THE FUEL test procedure. Refer to CHECKING FOR PROPER ETHANOL LEVEL IN THE GASOLINE .

   Is the fuel contaminated?

   Yes 

   • Drain the Fuel from the fuel tank into an approved gas holding tank and add clean fuel. Refer to DRAINING FUEL TANK .

   No 

   • Go To  8

1. Turn the ignition off.
2. Remove the Spark Plugs.
3. Inspect the Spark Plugs and Ignition Coils/Ignition cables for the following conditions:
   • Cracks
   • Carbon Tracking
   • Foreign Material
   • Spark Plug gap size out of specifications
   • Loose or broken electrode
   • Fouling
   NOTE:

   Lightly tap the bottom of the spark plug on a solid surface. The electrode in the spark plug should not move.

   Were any of the above conditions present?

   Yes 

   • Replace the Spark Plugs. If a Spark Plug was found to have carbon tracking or was fouled, verify that the Ignition Coil is not damaged.
   • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .

   No 

   • Go To  9

Check for any of the following conditions/mechanical problems:

1. • ENGINE VACUUM - must be at least 13 inches in neutral
   • ENGINE VALVE TIMING - must be within specifications
   • ENGINE COMPRESSION - must be within specifications
   • ENGINE EXHAUST SYSTEM - must be free of any restrictions or leaks.
   • ENGINE PCV SYSTEM - must flow freely
   • TORQUE CONVERTER STALL SPEED - must be within specifications
   • POWER BRAKE BOOSTER - no internal vacuum leaks
   • FUEL - must be free of contamination
   • CYLINDER LEAKAGE TEST - must be within specifications

   Are there any engine mechanical problems?

   Yes 

   • Repair as necessary.
   • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .

   No 

   • Go To  10

1. Perform any Service Bulletins that may apply.
2. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the related components and the Powertrain Control Module (PCM).
3. Look for any chafed, pierced, pinched or partially broken wires.
4. Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the related Sensors, Coils, Injectors and the Powertrain Control Module connectors.

   Were there any problems found?

   Yes 

   • Repair as necessary.
   • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .

   No 

   • Replace and program the Powertrain Control Module in accordance with the Service Information.
   • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .