H - Testing Notes

NOTE: You should enter this Pinpoint Test only when you have been directed here from Quick Test or Pinpoint Test S.


REMEMBER


To prevent the replacement of good components, be aware that the following non-EEC areas may be at fault.


- Ignition System

- Evaporative Emissions System

- Positive Crankcase Ventilation System

- Thermactor System

- Exhaust Gas Recirculation System

- Air Intake System/Filter

- Fuel and Engine Oil contamination

- Electrical System

- Fuel System

- Intake, Manifold, Supercharger, Intercooler Leaks

- Exhaust Manifold System Leak/Plugged

- Engine Cooling System

- Base Engine


This Pinpoint Test is intended to diagnose only the following:

- HEGO Sensor/heater

- HEGO Signal and Ground Circuit

- HEGO Sensor Connection

- Vacuum System

- Fuel Injector

- Fuel Injector electrical circuits

- Processor Assembly

- Harness circuits: HEGO GND, HEGO, INJ. 1-8, VPWR, SIG RTN


DESCRIPTION


The Heated Exhaust Gas Oxygen (HEGO) sensor reacts with the oxygen in the exhaust gases and generates a voltage based on this reaction. A low voltage indicates too much oxygen or a lean condition. A high voltage indicates not enough oxygen or a rich condition. The fuel injection is a typical on/off device. The amount of fuel delivered is determined by how long the injector is held open.