PCV System
This system removes blow-by gases from the crankcase and routes them back into the engine to be burned.
What is the Positive Crankcase Ventilation (PCV) system?
This emissions system helps reduce emissions primarily during cold engine starts.
What is the Secondary Air Injection (AIR) system?
This test measures restriction inside the exhaust system.
What is an exhaust backpressure test?
A rattling noise inside a catalytic converter usually indicates this.
What is a loose or damaged substrate?
A technician finds cracked AIR hoses and poor airflow from the pump. The next step is this.
What is repair or replace the damaged hoses and verify proper airflow?
Before inspecting or servicing a PCV system, technicians should always consult this.
What is the manufacturer's service information?
When checking AIR system operation, technicians should verify this after starting the engine.
What is airflow through the air pump lines?
Before connecting the backpressure gauge, technicians remove this component.
What is the oxygen sensor?
This tool is commonly used to compare inlet and outlet converter temperatures.
What is an infrared thermometer?
A vehicle has excessive exhaust backpressure at idle and at 2,500 RPM. The technician should suspect this.
What is an exhaust restriction or plugged catalytic converter?
During a PCV diagnosis, this simple item is placed over the oil fill opening to verify crankcase vacuum.
What is a piece of paper (or a 3" × 5" card)?
Technicians inspect these for corrosion or damage during AIR system diagnosis.
What are the hoses, check valves, and metal lines?
Maximum allowable exhaust backpressure at idle is this value.
What is 1.25 psi?
This test enriches the exhaust stream to evaluate converter performance.
What is the propane enrichment test?
During a PCV inspection, the valve is completely clogged. The technician should recommend this.
What is replacing the PCV valve according to manufacturer recommendations?
If the paper is held tightly against the oil fill opening, it indicates this.
What is proper crankcase vacuum and a functioning PCV system?
If an AIR pump is belt driven, technicians should inspect this.
What is the drive belt for cracks and proper tension?
Maximum allowable exhaust backpressure at 2,500 RPM is this value.
What is 2.5 psi?
This tool measures exhaust gases before and after the converter.
What is an exhaust gas analyzer?
A failed AIR check valve allows exhaust gases into the air pump. What components could be damaged?
What are the air pump, hoses, and switching valves?
During diagnosis, crankcase vacuum should be approximately this value.
What is about 0.5 in. Hg (or about 7 inches of water)?
A failed one-way check valve may allow these to damage the AIR system.
What are hot exhaust gases?
Before replacing a catalytic converter, technicians should perform this test.
What is an exhaust backpressure test?
Comparing temperatures before and after the catalytic converter helps determine this.
What is whether the catalytic converter is functioning properly?
A vehicle has poor power, high exhaust backpressure, and a rattling catalytic converter. What is the most likely diagnosis?
What is a failed or restricted catalytic converter?