GM Camaro/Firebird 1993-1998 Repair Guide

Diagnosis and Testing

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SYSTEM TESTING



See Figures 1, 2, 3 and 4

Effective troubleshooting of the Opti-Spark ignition system requires a logical and systematic approach. The following charts are designed to help diagnose a no-spark condition or erratic spark plug firing. Refer to the system wiring chart before making any tester connections, and follow the steps in their prescribed order.


CAUTION
When handling secondary spark plug leads with the engine running or starting, insulated pliers must be used and care exercised to prevent a possible electrical shock.



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Fig. Fig. 1: Ignition system wiring-5.7L VIN P engine



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Fig. Fig. 2: Ignition system check-5.7L VIN P engine



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Fig. Fig. 3: Ignition system check-5.7L VIN P engine



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Fig. Fig. 4: Ignition system diagnosis for misfire-5.7L VIN P engine

SPARK TEST



  1. With the engine off, disconnect a spark plug wire from a spark plug.
  2.  
  3. Connect a spark tester, such as tool ST-125, to the plug wire. Attach the clip to a good ground.
  4.  
  5. Have an assitant crank the engine. Check for spark at the tester. If there is no spark at one wire, check a second wire. It should be a bright blue color; if it is not, the coil may be faulty.
  6.  

IGNITION COIL



  1. Using an ohmmeter (on the high scale), connect the probes between the primary (low voltage) terminal and coil ground. The reading should be very high and infinity; if not, replace the coil.
  2.  
  3. Using an ohmmeter (on the low scale), connect the probes between both primary terminals. The reading should be very low or zero; if not, replace the coil.
  4.  
  5. Using an ohmmeter (on the high scale), connect the probes between a primary terminal and the secondary (high voltage) terminal. The reading should be high (not infinite); if not, replace the coil.
  6.  

DISTRIBUTOR VENTILATION SYSTEM



See Figure 5

The distributor ventilation system is used on 1994-98 vehicles. The distributor ventilation system vacuum harness is connected to the air intake duct, the distributor and the intake manifold. The vacuum harness provides ventilation for the distributor, preventing any moisture from accumulating and causing ignition system problems or failure.

The distributor vacuum harness attaches to the air intake duct and the intake manifold with vacuum fittings. It connects to the distributor at two places with separately sized connectors.

  1. If ignition system failure should occur, check the vacuum harness for proper hook-up and/or kinks.
  2.  



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Fig. Fig. 5: Distributor ventilation system components

  1. If they are OK, check the distributor ventilation system for a possible restriction before removing the distributor, as follows:
    1. Disconnect the vacuum harness from the air intake duct and check for vacuum using a vacuum gauge.
    2.  
    3. The vacuum gauge needle should slowly move towards manifold vacuum.
    4.  
    5. If no vacuum is present, replace the vacuum harness.
    6.  

  2.  
  3. Once you determine the distributor ventilation system vacuum harness is operating properly, disconnect the vacuum gauge and reconnect the vacuum hose to the air intake duct.
  4.  

 
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