Important Preliminary Checks Before Starting
Before using this section, perform the Powertrain On-Board diagnostic
(OBD) System Check to verify the following items:
| • | The PCM and MIL (Service Engine Soon) are operating correctly. |
| • | There are no DTC(s) stored. |
| • | Ensure that the engine coolant temperature is not above 130°C
(266°F). This will cause the PCM to operate in the Engine Metal Overtemp
mode. While in this state, the PCM will turn OFF four cylinders at a time
to prevent the engine coolant temperature from reaching damaging levels.
Engine Metal Overtemp can be perceived as a lack of power, engine miss, or
rough idle. If the engine is operating in the Engine Metal Overtemp mode,
refer to DTC P1258. |
| • | Scan tool data is within the normal operating range. Refer to
Typical Scan Data Values. |
| • | Verify the customer's complaint to reference the correct symptom
table. |
Visual/Physical Check
Several of the symptom procedures call for a careful Visual/Physical
check. It can lead to correcting a problem without further checks and can
save valuable time. This check includes the following items:
| • | PCM grounds for being clean, tight, and in the proper location. |
| • | Vacuum hoses for splits, kinks, and proper routing and connections.
Refer to the Vehicle Emission Control Information label. Check thoroughly
for any type of leak or restriction. |
| • | Intake air system for the following conditions: |
| - | Dirty or damaged air cleaner element or housing. |
| - | Damaged or collapsed intake air ducting. |
| - | Poor intake air system connections. |
| • | Air leaks at the throttle body and/or intake manifold. |
| • | Throttle body contaminants or deposits. |
| • | Accelerator cable binding or damage. |
| • | Ignition system wiring for incorrect routing and/or poor connections. |
| • | System wiring for routing near high frequency devices (EMI condition). |
| • | Engine cooling system leaks. Refer to Engine Cooling. |
The following Symptom tables are located in this section:
