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. |
|
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 adequate secondary ignition voltage with a J 26792
spark tester or an equivalent. |
| • | 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
|
| • | Inspect the exhaust system for damaged or collapsed pipes. Inspect
the muffler for heat distress or an internal failure. |
|
Additional Checks
|
| • | Verify the PCM grounds are clean, tight, and in the proper locations. |
| • | 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.
|
