Checks
| Action
|
Definition: Engine
delivers less than expected power. Little or no increase in speed when the
accelerator pedal is pushed down part way.
|
Preliminary Checks
|
• | Refer to
Symptoms
,
Important Preliminary Checks Before Starting. |
• | Check the PCM grounds for being clean, tight and in their proper
locations. Refer to PCM wiring diagrams . |
|
Fuel System Checks
|
• | Check both injector fuses for being open. An open injector fuse
causes four ignition coils and four injectors not to operate. Replace the
fuse. Inspect the ignition coil circuits and the injector circuits for
an intermittent short to ground. |
|
Sensor/System
|
• | Check the generator output voltage. Refer to Engine Electrical
. |
|
Ignition System
|
• | Check both injector fuses for being open. An open injector fuse
causes four ignition coils and four injectors not to operate. Replace the
fuse. Inspect the ignition coil circuit and the injector circuits for
an intermittent short to ground. |
• | Wet down the secondary ignition system with water from a spray
bottle. Wetting the secondary ignition system may help locate damaged or deteriorated
components. Look/listen for arcing or misfiring as water is applied. |
• | Check for proper ignition voltage output with spark tester J 26792
. |
• | Remove the spark plugs and check for the following: |
• | An improper spark plug gap will cause a driveability problem.
Refer to Engine Electrical/Spark Plugs . Do the spark plug gapping using
a wire gauge gap tool (J 41319). Refer to
Spark Plug Replacement
. Determine the cause of the fouling before
replacing the spark plugs if spark plugs are gas or oil fouled. Refer
to
Fuel System Diagnosis
for
diagnosis of the rich condition or Engine/Engine Mechanical for diagnosis
of the oil fouling condition. |
|
Engine Mechanical
|
• | Ensure that the engine coolant temperature 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 will turn fuel off to four cylinders at a time
to keep engine temperatures from reaching damaging levels. The system
perceives the 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/Engine Cooling for diagnosis. |
• | Excessive oil in combustion chamber-Leaking valve seals.
Refer to Engine/Engine Mechanical. |
• | Low cylinder compression. Refer to Engine/Engine Mechanical. |
• | For incorrect basic engine parts. Inspect the following: |
Refer to Engine/Engine Mechanical.
|
Additional Checks
| Check the exhaust system for possible restrictions. Check for the following:
• | Inspect the exhaust system for damaged or collapsed pipes. |
• | Inspect the exhaust manifold for a collapsed inner wall. |
• | Inspect the mufflers for heat distress or possible internal failure. |
• | Inspect for possible plugged catalytic converters by comparing
exhaust system back pressure on each side of engine. Check back pressure by
removing Heated Oxygen Sensor (HO2S) near exhaust manifolds. Refer to
Restricted Exhaust System Check
and
Engine/Engine Exhaust . |
|