Inspections
| Action
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DEFINITION: A steady pulsation or jerking that follows engine speed, which is usually more pronounced as the 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 at low speed.
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Preliminary
|
• | Verify that the ECM and ECM bracket fasteners are at the correct torque. |
• | Inspect the intake air duct and air cleaner outlet resonator for the following conditions: |
- | Improperly installed hoses |
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Fuel System
|
• | Test the items that cause an engine to run rich. For a rich condition, refer to
DTC P2178
or
DTC P2188
. |
• | Test the items that can cause an engine to run lean. For a lean condition, refer to
DTC P2177
or
DTC P2187
. |
|
Sensor/System
| Monitor the knock sensor (KS) system for excessive spark retard activity with a scan tool. Refer to
Knock Sensor (KS) System Description
,
DTC P0327 or P0332
, and
DTC P0328 or P0333
.
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Ignition System
|
• | Inspect for the correct installation of the ignition coil seals. Incorrect installation may allow water to enter the spark plug area. Inspect for moisture and corrosion. |
• | Remove the spark plugs and inspect for the following conditions: |
- | Refer to the following procedures: |
• | If the spark plugs are gas, coolant or oil fouled, determine the cause before replacing the spark plugs. Refer to the following procedures: |
- | For diagnosis of coolant contaminated spark plugs, refer to
Loss of Coolant
. |
• | Inspect the spark plug boots and terminals for burning or micro-arcing, corrosion, and damage to the insulation. |
• | Inspect the crankshaft position (CKP) sensor for the correct resistance. The sensor resistance may be out of range after a hot soak. Measure that the resistance remains within 700-1,200 ohms at all temperatures. |
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Engine Mechanical
|
• | Inspect for the following engine mechanical conditions: |
- | Excessive oil in combustion chamber or leaking valve seals |
- | Incorrect cylinder compression |
- | Sticking or leaking valves |
- | Excessive carbon buildup in the combustion chambers--Clean the chambers with top engine cleaner. Follow the instructions on the can. |
- | For more information, refer to the following procedures: |
• | Inspect the following components for incorrect basic engine parts: |
- | Pistons, connecting rods, or bearings. |
- | Refer to the following procedures: |
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Additional
|
• | Inspect the following exhaust system components: |
- | The exhaust system for damage |
- | The mufflers for heat distress or possible internal failure |
- | The three-way catalytic converters for restrictions |
• | Electromagnetic interference (EMI) on the CKP sensor signal circuits can cause an engine misfire condition. You can usually detect EMI with a scan tool by monitoring the engine speed parameter. A sudden increase in the engine speed parameter, with
little change in actual engine speed indicates that EMI is present. Inspect for high voltage components near the ignition control circuits if a condition exists. Also, inspect the engine ground shield of the CKP sensor circuits. |
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