Important Preliminary Checks Before Starting
Before using this section, perform
Diagnostic System Check - Engine Controls
to verify the following
items:
| • | The powertrain control module (PCM) and malfunction indicator
lamp (MIL) Service Engine Soon are operating correctly. |
| • | There are no diagnostic trouble codes (DTCs) 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. |
| • | Verify the customers complaint to reference the correct symptom
table. |
Visual/Physical Check
Several of the symptom procedures call for a careful Visual/physical
check. The visual/physical check can lead to correcting a problem without
further checks and can save valuable time. This check includes
the following items:
| • | Powertrain control module (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 ducts |
| - | 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) |
The following Symptom tables are located in this section:
