Lack Of Power, Sluggishness, Or Sponginess
Checks
| Action
|
DEFINITION: The engine delivers less than expected power. There is little or
no increase in speed when partially applying the accelerator pedal.
|
Preliminary Checks
|
• | Compare the customers vehicle with a similar unit in order to determine
if the customer has an actual problem. |
• | Remove the air filter element and check for dirt or restrictions. |
• | Check the air inlet duct for any blockage or restrictions. |
• | Check the transmission shift pattern and down-shift operation. |
|
Sensor/System
| Inspect the mass air flow (MAF) sensor operation. Run the engine to normal operating
temperature. Turn OFF all accessories and observe the MAF sensor at idle with a scan
tool. If the MAF sensor reading is more than 3.5 g/s refer to
DTC P0101
.
|
Fuel System Checks
|
• | Check for a restricted fuel filter or incorrect fuel pressure. |
• | Check the fuel injectors. Perform the following procedures: |
|
Ignition System Checks
|
• | Check for the proper ignition voltage output with a
J 26792
Spark Tester. |
• | Inspect the spark plugs for correct operation and good ignition system
performance. Refer to
Spark Plug Inspection
. |
• | Check the knock sensor (KS) and the sensor circuit shielding. A faulty
knock sensor or signal interference could cause excessive retard of the ignition timing
advance. Observe the spark parameter on a scan tool and compare with a known good
vehicle. A typical value at 98 km/h (60 mph) with all engine accessories
off is 26-32 degrees. |
|
Exhaust System Checks
|
• | Check the exhaust system for a possible restriction. Refer to
Restricted Exhaust
in Engine Exhaust. |
• | Inspect the exhaust system for damaged or collapsed pipes. Inspect the
muffler for heat distress or a possible internal failure. |
|
Engine Mechanical Check
|
• | Check for any of the following engine mechanical problems: |
- | An incorrect valve timing |
- | An incorrect or worn camshaft |
|
Additional Checks
|
• | If the loss of power is great above 6,000 RPM, inspect for the
correct operation of the Rocker Arm Oil Control system. Refer to
DTC P2647
. |
• | If there is a slight loss of power at wide open throttle (WOT), inspect
for the correct operation of the Auxiliary Intake Air Control system. Refer to
Auxiliary Intake Air System Diagnosis
. |
• | Check the powertrain control module (PCM) grounds for being clean, tight,
and in the proper locations. Refer to
Engine Controls Schematics
. |
• | Check the generator output voltage. |
|