DR-21

TEST DR-21 PERFORMING NO FAULT CODE MECHANICAL TEST
Perform TEST DR-17 Before Proceeding

At this point in the driveability lest 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.
Spec: With no vacuum at the regulator: 48 PSI on V6 & non-turbo 4 Cyl. engines 36 PSI on turbo engines.