Inspections
| Action
|
DEFINITION: Steady pulsation or jerking that follows engine speed, usually more pronounced as engine load increases. This condition is not normally felt above 1,500 RPM or 48 km/h (30 mph). The exhaust has a steady spitting sound
at idle or low speed.
|
Preliminary
|
|
Fuel System
|
• | Inspect for the following conditions 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 heated oxygen sensor (HO2S) connector |
- | Purging of a saturated evaporative emission (EVAP) canister |
- | Proper operation of the manifold absolute pressure (MAP) sensor--Refer to
DTC P0106
. |
- | Vacuum hoses that are split, kinked, or improperly connected |
- | An air intake duct that is collapsed or restricted |
• | Inspect for the following conditions 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
. |
- | Proper operation of the MAP sensor--Refer to
DTC P0106
. |
- | Vacuum hoses that are split, kinked, or improperly connected |
|
Sensor/System
|
• | Use a scan tool in order to monitor the knock sensor (KS) system for excessive spark retard activity. Refer to
Scan Tool Data List
. |
• | Inspect for throttle body tampering, excessive deposits, or damage. |
• | Inspect for a vacuum leak. |
|
Ignition System
|
• | In order to properly inspect the spark plugs or to correct a condition, refer to the following procedures: |
• | Inspect for proper secondary ignition voltage output with
J 26792
HEI Spark Tester. |
• | An improper spark plug gap will cause a driveability condition. Gap the spark plugs using a wire gage gap tool. |
• | If the spark plugs are found to be fouled, determine the cause before replacing the spark plugs. |
• | Monitor the Misfire Current Counters while driving the vehicle in the conditions that the symptom occurred. If a misfiring cylinder can be located, use the DTC P0300 table for diagnosis. Refer to
DTC P0300
. |
• | Soak the secondary ignition system with water from a spray bottle. Soaking the secondary ignition system may help locate damaged or deteriorated components. Look and listen for arcing or misfiring as you apply the water. |
|
Engine Mechanical
|
• | Inspect engine mechanical for the following: |
- | Sticking or leaking valves |
- | Excessive oil in combustion chamber or leaking valve seals. |
- | For more information, refer to one or more of the following procedures in Engine Mechanical: |
• | For incorrect, worn, or damaged basic engine parts, inspect the following: |
• | Inspect for excessive end play that will cause the crankshaft position (CKP) sensor reluctor wheel to move out of alignment with the CKP sensor. Refer to
Crankshaft and Bearing Cleaning and Inspection
. This
could result in any of the following conditions. |
|
Additional Inspections
|
• | Inspect the exhaust system for possible restrictions. Inspect for the following: |
- | Inspect the exhaust system for damaged or collapsed pipes. |
- | Inspect the mufflers for heat distress or possible internal failure. |
• | Electromagnetic interference (EMI) can cause an engine misfire condition. A sudden increase in indicated RPM parameter with little change in actual engine RPM change indicates EMI is present. Inspect for high voltage components near ignition control
circuits if a condition exists. |
• | Inspect the intake manifold and the exhaust manifold passages for casting flash. |
|