Inspection and Verification

Exhaust Leakage or Noise

Exhaust system performance complaints such as excessive back pressure, exhaust odor or excessive noise are usually noticeable by their effect on the performance of the engine (6007).

However, other malfunctioning components may have similar effects on the performance of theengine and be characterized by the same symptoms or complaints. Refer to Powertrain Control/Emissions Diagnosis Manual OBDI or OBDII.

For general exhaust system complaints, refer to the pinpoint tests in this section.

1. Visually inspect the components of the catalytic converter and exhaust system and related controls that may affect exhaust gas quality or cause backfire or loss of power.

   
   
   

   VISUAL INSPECTION CHART

   Mechanical	Electrical
   Leaking fuel injector nozzle tips Damaged air inlet passages Inoperative exhaust gas recirculation (EGR) valve Exhaust pipe pinched, crushed Damaged, loose vacuum hoses Incorrect idle speed Dirty engine air cleaner Damaged catalytic converter	Misrouted, damaged wiring Damaged ignition coil, distributor or spark plugs Corroded, loose connectors

   
   

2. Inspect and wiggle the wiring connectors and the solenoids and other components for obvious problems due to looseness, corrosion, or other damage. This must be done when the engine is at operating temperature so as to activate the system controls.

3. Check the vacuum tubing and connections for looseness, pinching, leakage, splitting, blockage, or other damage that may cause malfunction.

4. If a vacuum tube or orifice (restrictor) blockage is suspected as the obvious cause of malfunction, correct the cause before proceeding to the next step.

5. Check engine oil for fuel dilution.

6. If all checks are OK, proceed to the pinpoint tests.