Lack of Power, Sluggish or Spongy
Inspection/Tests
| Action
|
DEFINITION: Engine
delivers less than expected power. Little or no increase in speed when
the accelerator pedal is pushed down part way.
|
Preliminary Inspections
|
• | Verify that the powertrain control module (PCM) grounds are clean, tight, and in the proper locations. |
|
Fuel System
|
• | Inspect 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. |
• | Inspect for the following that may cause the engine to run rich: |
Notice: Refer to Heated Oxygen and Oxygen Sensor Notice in the Preface section. - | Water intrusion in the HO2S connector |
- | Engine oil contaminated by fuel |
- | An EVAP canister purge condition |
- | An inaccurate mass air flow (MAF) sensor |
- | Vacuum hoses that are split, kinked, or improperly connected |
• | Inspect for the following conditions that may cause the engine to run lean: |
Notice: Refer to Heated Oxygen and Oxygen Sensor Notice in the Preface section. - | Water intrusion in the HO2S connector |
- | An exhaust leak between the HO2S and the engine. |
- | An inaccurate MAF sensor |
- | Vacuum hoses that are split, kinked, or improperly connected |
|
Sensor/System
| Use a scan
tool in order to monitor the knock sensor (KS) system for excessive spark
retard activity. Refer to
Knock Sensor (KS) System Description
.
|
Ignition System
|
• | Verify that both fuel injector fuses are not open. An open fuel injector fuse causes four ignition coils and four fuel injectors not to operate. Inspect the ignition coil circuit and the injector circuits for an intermittent short to ground. Refer to
Circuit Testing
in Wiring Systems. Replace the fuse. |
• | Soak the secondary ignition system with water from a spray bottle. Soaking the secondary ignition system may help locate damaged or deteriorated components. Look and listen for arcing or misfiring as water is applied. |
• | Inspect for proper ignition voltage output with the J 26792
Spark Tester . |
• | Remove the spark plugs and inspect for the following: |
Refer to
Spark Plug Inspection
.
• | 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. |
• | Monitor the Misfire Current Counters while driving the vehicle within the conditions that the misfire occurred. If a misfiring cylinder can be located with a misfire, use the DTC P0300 table for diagnosis. Refer to
DTC P0300
. |
|
Engine
Mechanical
|
• | Verify 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 will disable the fuel injectors 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. |
• | Inspect for excessive oil in the combustion chambers and leaking valve seals. Refer to
Oil Consumption Diagnosis
in Engine Mechanical. |
• | Inspect for incorrect basic engine parts, including the following: |
Refer to Engine/Engine Mechanical.
|
Additional Inspections
|
• | Inspect the exhaust system for possible restrictions. Perform the following: |
- | Inspect the exhaust system for damaged or collapsed pipes. |
- | Inspect the mufflers for heat distress or internal failure. |
- | Inspect for plugged three-way catalytic converters by comparing the exhaust system back pressure on each side of the engine. Test back pressure by removing the secondary air injection (AIR) check valves near the exhaust manifolds. |
• | Inspect the transmission torque converter clutch (TCC) for proper operation. |
|