Checks
| Action
|
DEFINITION: Engine
power variation under steady throttle or cruise. Feels like the vehicle
speeds up and slows down with no change in the accelerator
pedal position.
|
Preliminary
|
| • | Be sure the driver understands the operation of the transmission
torque converter clutch (TCC) and A/C compressor operation as explained
in the owners manual. Inform the customer how the TCC
and the A/C clutch operates. |
|
Sensor/System
|
| • | Check the heated oxygen sensors (HO2S). The HO2S should respond
quickly to different throttle positions. If they DO NOT, check the HO2S
for silicon or other contaminates from fuel or the use
of improper RTV sealant. The sensors may have a white , powdery
coating and result in a high but false signal voltage rich
exhaust indication. The PCM will then reduce the amount
of fuel delivered to the engine causing a severe driveability
problem. For more information, refer to
Oil Consumption Diagnosis
in Engine Mechanical. |
| • | Check the MAF sensor connections. Repair or replace terminals.
Refer to
Connector Repairs
in
Wiring Systems. |
|
Fuel
System
|
| • | Check that each injector harness is connected to the correct injector
or cylinder according to the firing order firing order: 1-8-7-2-6-5-4-3.
Relocate injector harnesses as necessary. |
| • | Check the items that cause an engine to run rich long term fuel
trim near-13 percent. For a rich condition, refer to
DTC P0172 or P0175
. |
| • | Check the items that can cause an engine to run lean long term
fuel trim near 24 percent. For a lean condition, refer to
DTC P0171 or P0174
. |
|
Ignition
System
|
| • | Wet down the secondary ignition system with water from a spray
bottle. Wetting down the secondary ignition system may help locate damaged
or deteriorated components. Look and listen for arcing
or misfiring as you apply the water. |
| • | Remove the spark plugs and check for the following: |
| • | An improper spark plug gap will cause a driveability problem.
Gap the spark plugs using a wire gauge gap tool. Refer
to
Spark Plug Replacement
. |
| • | Determine the cause of the fouling before replacing the spark
plugs if the spark plugs are gas, coolant, or oil fouled. Refer to one
of the following procedures: |
| • | Monitor the Misfire Current Counters while driving the vehicle
in the conditions that the misfire occurred. If a cylinder can be located
with a misfire, use the DTC P0300 table for diagnosis. |
|
Engine
Mechanical
| Ensure that the engine coolant temperature (ECT) is not above 130°C (266°F).
This condition causes the PCM to operate in Engine Coolant Over
Temperature-Fuel Disabled Mode. While in Engine Coolant Over
Temperature-Fuel Disabled Mode, the PCM turns fuel OFF
to four cylinders at a time to keep engine temperatures
from reaching damaging levels. The system perceives Engine
Coolant Over Temperature-Fuel Disabled Mode as a
lack of power, miss, or rough idle. If the vehicle operates
in Engine Coolant Over Temperature-Fuel Disabled Mode, refer
to
Engine Overheating
in Engine
Cooling for diagnosis.
|
Additional Checks
|
| • | Visually (physically) check vacuum hoses for splits, kinks, and
proper connections and routing as shown on Vehicle Emission Control Information
label. |
|
