Checks
| Action
|
Definition: Steady
pulsation or jerking that follows engine speed, usually more pronounced as
engine load increases. This condition is not normally
felt above 1500 RPM or 48 km/h (30 mph). The exhaust has a steady spitting
sound at idle or low speed.
|
Preliminary
|
• | Refer to
Symptoms
,
Important Preliminary Checks Before Starting. |
|
Fuel
System
|
• | Test for a contaminated fuel condition Refer to Alcohol/Contaminants-in-Fuel Diagnosis
. |
|
Sensor/System
| Use a scan
tool in order to monitor the KS system for excessive spark retard activity.
|
Ignition System
|
• | Wet down the secondary ignition system with water from a spray
bottle. Wetting down the secondary ignition system may help locate damaged
or deteriorated components. Look/listen for arcing or misfiring as you
apply water. |
• | Test for proper ignition voltage output with spark tester J 26792
. |
• | Remove the spark plugs and inspect for the following: |
• | Visually/Physically inspect the Secondary ignition for the following: |
- | Ignition wires arcing to ground |
- | Ignition wires for proper routing |
- | Ignition coils for cracks or carbon tracking |
|
Engine
Mechanical
|
• | Inspect engine mechanical for the following: |
- | Test compression. Refer to Engine Compression Test
in Engine Mechanical 5.7L. |
• | For incorrect basic engine parts. Inspect the following: |
|
Additional
Checks
|
• | Inspect exhaust system for possible restrictions. Inspect for
the following: |
- | Inspect the exhaust system for damaged or collapsed pipes. |
- | Inspect the exhaust manifold for a collapsed inner wall. |
- | Inspect the mufflers for heat distress or possible internal failure. |
• | Electromagnetic Interference (EMI) on the reference circuit can
cause an engine miss condition A sudden increase in RPM with little change
in actual engine RPM change indicates EMI is present. Inspect routing
of secondary ignition wires, high voltage components (Near Ignition Control
circuits) if a condition exists. |
|