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 customer vehicle with a similar vehicle in order to
determine the severity of the customer concern. |
| • | Remove the air filter element and check for dirt or restrictions. |
| • | Check the transmission shift pattern and down shift operation.
Refer to
Road Test
in Automatic
Transmission. |
|
Fuel System Checks
|
| • | Check for a restriction in the fuel supply system. Check for the
correct fuel pressure. Refer to
Fuel System Diagnosis
. |
|
Ignition System Checks
|
| • | Check for the proper operation of the ignition control system. |
| • | Check the camshaft position (CMP) sensor engine reference signal
with a scan tool. Observe the Engine Speed parameter while operating the engine
at the speed of the concern. The scan tool should indicate steady and
linear RPM readings while running. If the erratic values, such as sudden
spikes or drops in engine speed are displayed, the engine reference
signal is not stable enough for the engine to run properly. Inspect
the CMP sensor signal rotor and housing for worn bushings or drive coupling.
Inspect for electromagnetic interference (EMI) of the reference signal. |
|
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 an internal failure. |
|
Additional
Checks
|
| • | Verify the powertrain control module (PCM) grounds are clean,
tight, and in the proper locations. Refer to
Engine Controls Schematics
. |
| • | Check the generator output voltage. |
|
Engine Mechanical
Check
| Check
for any of the following engine mechanical problems:
| • | An incorrect valve timing |
| • | An incorrect or worn camshaft |
Refer to
Engine Compression Test
in Engine Mechanical.
|
