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 sensors circuit shielding.
The knock sensor is not diagnosed for excessive activity. 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 with the transmission in
OD at 105 km/h (65 mph) 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
|
• | 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. |
|