Visual Inspection

Component Locations:

1. All diagnostic procedures must start with a thorough visual inspection of the vehicle.
2. Multipoint injection (MPI) system components are shown in Fig. 1 & 2. Your visual inspection should start with electrical connections and harness condition at the components shown. Connectors and terminals must lock together. Look for terminals that are pushed out, loose or corroded. Make sure that wiring between each connector is not pinched behind any screws or bolts, or rubbing on drive belts, sharp metal, or exhaust systems.
3. Look for any added accessories that may affect the normal operation of the MPI system (alarms, kill switches, etc.).
4. All hose and vacuum line connections must be secure and hoses must not be pinched, collapsed, or cut. (Refer to Emission Control Systems/Diagrams/Vacuum and Vapor Hose)
5. On all vehicles with an airflow sensor, intake hoses and air cleaner housings must be in place and secure for normal operation and testing.
6. Vehicle battery must be fully charged.

The following additional items cannot be overlooked as possible causes of a driveability problem:
1. Throttle valve area -- Dirt or ice buildup causing rough idle and stalling.
2. Engine ignition timing -- Must be set with timing terminal grounded.
3. Engine vacuum -- Must be normal for your altitude.
4. Engine valve timing -- To specifications.
5. Engine compression -- To specifications.
6. Engine P.C.V. system -- Must flow freely.
7. Engine exhaust system -- Must be free of any restrictions.
8. Power brake booster - No internal vacuum leaks,
9. Torque converter condition -- May cause very low power at breakaway or high speed (Only 1 condition at a time)
10. Fuel contamination -- High alcohol or water content.
11. Fuel injectors-- Rough idle may be caused by injector wiring not connected to correct injector. (On 1 .5L engines, blue injector connectors are located at cylinders 1 and 4.)
12. Engine secondary ignition check - Abnormal scope patterns.
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. With no vacuum applied at the regulator: 48 psi on V6 and non-turbo 4 cyl. 36 psi on turbo engines.