Important Preliminary Checks Before Starting
Before using this section, perform the
Powertrain On Board Diagnostic (OBD) System Check
and verify all
of the following items are true:
| • | The PCM and MIL are operating correctly. |
| • | There are no DTCs stored. |
| • | Ensure that the engine coolant temperature is not above 128°C
(262°F). This condition will cause the PCM to operate in Coolant Hot Mode.
While in Coolant Hot Mode, the PCM will turn fuel OFF to three cylinders
to keep engine temperatures from reaching damaging levels. Coolant
Hot Mode will be perceived as a lack of power, miss, or rough idle.
If the vehicle is operating in Coolant Hot Mode, refer to
Engine Overheating
. |
| • | Verify the customer complaint and locate the applicable symptoms.
Perform the procedure included in the symptom diagnostic table. |
Visual/Physical Checks
Several of the symptom procedures call for a visual/physical inspection.
A careful visual/physical inspection can aid in correcting a problem without
further checks and can save valuable time. A visual/physical inspection
should include the following items:
| • | The PCM grounds for being loose, corroded, or in an improper location. |
| • | The vacuum hoses for splits, kinks, and improper connections.
The proper connections are shown on the Vehicle Emission Control Information
label. Check the vacuum hoses for any type of leak or restriction.
Refer to
Emission Hose Routing Diagram
. |
| • | Inspect the air intake ducts for collapsed or damaged areas. |
| • | Check for air leaks at the throttle body mounting area, the mass
air flow (MAF) sensor, and the intake manifold sealing surfaces. |
| • | Inspect the ignition wires for cracking, hardness, proper routing,
and carbon tracking. |
| • | Inspect the wiring for improper connections, pinches, and cuts. |
The following Symptom tables are located in this section:
