Dr-22: No-Fault Code Mechanical Test

At this point in the driveability test procedure you have determined that all of the engine controls systems are operating as they were designed to. Therefore, they are not the cause of the driveability problem. The following additional items should be checked as possible causes:

1. ENGINE VACUUM
   
   Must be at least 13 inches in neutral.
2. ENGINE VALVE TIMING
   
   Set to specifications.
3. ENGINE COMPRESSION
   
   To specifications.
4. EXHAUST SYSTEM
   
   Free from any restrictions.
5. PCV SYSTEM
   
   Must flow freely.
6. DRIVE SPROCKETS
   
   Camshaft and crank shaft.
7. TORQUE CONVERTER STALL SPEED
   
   To specifications.
8. POWER BRAKE BOOSTER
   
   No internal vacuum leak.
9. FUEL CONTAMINATION
   
   High alcohol and water content.
10. FUEL INJECTORS
    
    Rough idle may be caused by injector control wire not connected to correct injector.
11. TECHNICAL SERVICE BULLETINS
    
    Any that may apply to vehicle.
12. ENGINE SECONDARY IGNITION CHECK
    
    Any abnormal scope pattern.
13. TECHNICAL SERVICE BULLETINS
    
    Any that apply to vehicle.
14. All air intake piping and vacuum hoses must be in place and secure. The proper air filter element must be used.
15. 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