Checks
| Action
|
DEFINITION: The engine delivers less than expected power.
The speed may increase slightly or may not increase when applying the accelerator
pedal.
|
Preliminary Checks
|
| • | Compare the customers vehicle with a similar vehicle in order
to determine how severe the customers concern is. |
| • | Remove the air filter element, and check the air filter element
for dirt or for restrictions. |
| • | Check the transmission shift pattern and the 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 with an equivalent. |
| • | Check for the correct operation of the ignition control system. |
| • | Check the reference signal from the CKP sensor 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 RPM readings and linear
RPM readings while running. If sudden increases or decreases in engine speed
are displayed, the engine reference signal is not stable enough for the engine
to run correctly. Check for a short to ground in the ignition reference low
circuit of the CKP sensor. A short to ground in the ignition reference low
circuit of the CKP sensor will cause a faulty engine reference signal to
be sent to the PCM.However, this will not set a CKP sensor DTC. |
|
Exhaust System Checks
|
| • | Inspect the exhaust system for damaged pipes or for collapsed
pipes. Inspect the muffler for heat damage or for a possible internal failure. |
|
Additional Checks
|
| • | Check the PCM grounds for being clean, tight, and in the correct
locations. Refer to Engine Controls Schematics
Cell 21: Power and Ground
. |
| • | Check the generator output voltage. |
|
Engine Mechanical Check
| Check for any of the following engine mechanical
conditions:
| • | An incorrect camshaft or a worn camshaft |
|
