If the statement is false, explain why it is false. A properly operating EGR value should not function during cold engine operation. At wide open throttle, the PCV should be closed, limiting flow to a minimum. An EGO sensor functions in both closed and open loop. High exhaust-oxygen levels always indicates an excessively lean condition.
Students frequently use acronyms freely without fully understanding what each letter represents.
This guide should help students correlate these acronyms with the purpose, function, or test, and probable malfunction for each of the four. By having students complete this exercise for two different vehicles, comparisons may be drawn. Carefully review student responses since many imported and late model domestic models use widely diverse systems. Wide-open throttle requires maximum flow. Vacuum approaches zero, thus, the valve fully opens.