Checks 
 | Action 
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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. 
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Preliminary 
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|     •  | Check the powertrain control module (PCM) grounds for being clean,
tight, and in the proper   locations. Refer to  
Engine Controls Schematics 
  . |  
  
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Fuel System 
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|     •  | Check items that cause an engine to run rich long term fuel trim
  near -13 percent. For a rich condition, refer to  
DTC P0132 or P0152 
     . |  
  
|     •  | Check items that can cause an engine to run lean (long term fuel
  trim near 24 percent. For a lean condition, refer to  
DTC P0131 or P0151 
    . |  
  
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Sensor/System 
 | Use a scan
tool in order to monitor the knock sensor (KS) system for excessive spark
 retard activity. 
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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 and listen for arcing
    or misfiring            as    you     apply    water. |  
  
|     •  | Check for proper ignition voltage output with J 26792 
 Spark Tester  . |  
  
|     •  | Remove the spark plugs and check for the following: |  
  
Refer to 
Spark Plug Inspection 
. 
|     •  | Determine the cause of the fouling before replacing the spark
  plugs if the spark plugs are gas, coolant, or oil fouled. Refer to  
DTC P0172 or P0175 
  for  diagnosis    of the rich
   condition. Refer to  
Spark Plug Inspection 
for
 diagnosis  of coolant     or oil fouled spark plugs. |  
  
|     •  |  Visually and physically inspect the secondary ignition for the
following: |  
  
|        -  | Ignition wires arcing to ground |  
  
|        -  | Ignition wires for proper engagement to spark plug |  
  
|        -  | Ignition coils for cracks or carbon tracking |  
  
|     •  | 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, use the DTC P0300 table for diagnosis. |  
  
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Engine Mechanical 
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|     •  | Check engine mechanical for the following: |  
  
|        -  | Sticking or leaking valves  |  
  
|        -  | Excessive oil in combustion chamber--Leaking valve seals.
Refer   to  
Oil Consumption Diagnosis 
         in Engine Mechanical  4.8L, 5.3L, 6.0L. |  
  
|     •  |  For incorrect basic engine parts inspect the following: |  
  
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Additional   Checks 
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|     •  | Check the exhaust system for possible restrictions. Check 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. |  
  
|        -  | Inspect for possible plugged 3-way catalytic converters by   comparing
the exhaust system back pressure on each side of engine. Check    back   
                   pressure by removing secondary air injection (AIR) check
 valves near exhaust    manifolds.          Refer       to  
Restricted Exhaust 
   in Engine Exhaust.       |  
  
|     •  | Electromagnetic interference (EMI) on the reference circuit can
  cause an engine miss condition A sudden increase in indicated RPM  with
    little                  change    in actual engine RPM change indicates
  EMI   is present.          Check  for high voltage components   near ignition
    control    circuits         if  a problem exists. |  
  
|     •  | Check the intake manifold and the exhaust manifold passages for
  casting flash.  |  
  
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