Dr-21: No Fault Code Mechanical Test

At this point in the driveability test procedure, you have determined that all of the engine control systems are operating as they were designed to. Therefore, they are not the cause of the driveability problem.

The following additional items can not be overlooked as possible causes of a driveability problem.

1. ENGINE IGNITION TIMING
   
   Must be set with timing terminal grounded.
2. ENGINE VACUUM
   
   Must be normal for your altitude.
3. ENGINE VALVE TIMING
   
   To specifications.
4. ENGINE COMPRESSION
   
   To specifications.
5. ENGINE P.C.V. SYSTEM
   
   Must flow freely.
6. ENGINE EXHAUST SYSTEM
   
   Must be free of any restrictions.
7. POWER BRAKE BOOSTER
   
   No internal vacuum leaks.
8. TORQUE CONVERTER CONDITION
   
   May cause very low power at breakaway or high speed (Only 1 condition at a time).
9. FUEL CONTAMINATION
   
   High alcohol or water content.
10. FUEL INJECTORS
    
    Rough idle may be caused by injector wiring not connected to correct injector.
11. ENGINE SECONDARY IGNITION CHECK
    
    Abnormal scope patterns.
12. TECHNICAL SERVICE BULLETINS
    
    Any that apply to vehicle.
13. All air intake piping and vacuum hoses must be in place and secure. The proper air filter element must be used.
14. FUEL PRESSURE
    
    Must be correct. Specification: With no vacuum at the regulator:
    • 48 PSI on V6 & non-turbo 4 Cyl. engines
    • 36 PSI on turbo engines