Inspections
| Action
|
DEFINITION: Engine delivers less than expected power. Little or no increase
in speed when the accelerator pedal is pushed down part way.
|
Preliminary
|
• | Ensure that the power take off (PTO) switch is in the OFF position. |
|
Fuel System
|
• | Inspect both ENG 2 and ENG 3 fuses for being open. An
open fuse causes four ignition coils and four injectors not to operate. Replace
the fuse. Inspect the ignition coil circuits and the injector circuits for an intermittent
short to ground. |
• | Inspect the following that may cause the engine to run rich: |
Notice: Refer to Heated Oxygen and Oxygen Sensor Notice in the Preface section. - | Water intrusion in the HO2S connector |
- | Engine oil contaminated by fuel |
- | An evaporative emission (EVAP) canister purge condition |
- | Vacuum hoses for splits, kinks and proper connections |
• | Inspect the following that may cause the engine to run lean: |
Notice: Refer to Heated Oxygen and Oxygen Sensor Notice in the Preface section. - | Water intrusion in the HO2S connector |
- | An exhaust leak between the HO2S and the engine--Refer to
Exhaust Leakage
in Engine Exhaust. |
- | Vacuum hoses for splits, kinks and proper connections |
|
Sensor/System
| Use a scan tool in order to monitor the knock sensor (KS) system for excessive
spark retard activity. Refer to
Knock Sensor (KS) System Description
.
|
Ignition System
|
• | Inspect both ENG 2 and ENG 3 fuses for being open. An
open fuse causes four ignition coils and four injectors not to operate. Replace
the fuse. Inspect the ignition coil circuit and the injector circuits for an intermittent
short to ground. |
• | Wet down the secondary ignition system with water from a spray bottle.
Wetting the secondary ignition system may help locate damaged or deteriorated components.
Look and listen for arcing or misfiring as water is applied. |
• | Test for proper ignition voltage output with J 26792
Spark Tester . |
• | An improper spark plug gap will cause a driveability problem. Gap the
spark plugs using a wire gage gap tool. Refer to
Spark Plug Replacement
. |
• | Determine the cause of the fouling before replacing the spark plugs
if the spark plugs are gas, coolant, or oil fouled. Refer to
Spark Plug Inspection
for diagnosis of fouled spark plugs. |
• | Monitor the Misfire Current Counters while driving the vehicle in the
conditions that the misfire occurred. If a cylinder can be located with a misfire,
refer to
Electronic Ignition (EI) System Diagnosis
for diagnosis. |
|
Engine Mechanical
|
• | Inspect the following components for incorrect basic engine parts: |
• | Inspect for excessive crankshaft endplay that will cause the CKP sensor
reluctor wheel to move out of alignment with the CKP sensor. Refer to
Crankshaft and Bearing Cleaning and Inspection
in Engine
Mechanical - 8.1L. This could result in any of the following conditions: |
Refer to the appropriate procedures in Engine Mechanical.
|
Additional
| Inspect the following components of the exhaust system for possible restrictions:
• | The exhaust system for damaged or collapsed pipes |
• | The exhaust manifold for a collapsed inner wall |
• | Compare the exhaust system back pressure on each side of engine. Refer
to
Restricted Exhaust
in Engine Exhaust. |
|