Ch. 85 Positive Crankcase Ventilation and Secondary Air-Injection Systems
A technician uses a scan tool to run the air pump on a warmed-up engine. What will this cause the HO2S voltages to do if the system is operating correctly?
Remain below .350 volt
Which of the following is true about the pumps used in a secondary air-injection (SAI) system?
When a belt-driven air pump rotates, underhood air is drawn into the pump and slightly compressed.
when checking for the proper operation of the AIR system using an exhaust gas analyzer how much should the oxygen levels increase when the pump is allowed to function?
1 to 4%
Which of the following statements is true of a closed-loop engine operation in the normal working of a typical secondary air-injection (SAI) system?
Air is diverted to the catalytic converter.
Which of the following is true of air distribution manifolds and nozzles?
An external air manifold has the nozzles threaded into the cylinder heads or exhaust manifolds close to each exhaust valve.
the SAI system is used to reduce which exhaust emissions?
Both HC and CO
Technician A says that if the PCV valve was defective or clogged, the engine could idle rough. Technician B says that the engine may stall. Which technician is correct?
Both technicians A & B
Two technicians are discussing exhaust check valves. Technician A states that when the exhaust pressure exceeds injection pressure, a check valve spring closes the valve to prevent reverse exhaust flow. Technician B states that when an air pump fails, the check valve spring closes the valve to prevent reverse exhaust flow. Which of the following statements is true in this scenario?
Both technician A's and B's assessments are accurate.
Two technicians were discussing positive crankcase ventilation (PCV) systems. Technician A said that if an engine idles rough, it indicates that the PCV system is blocked. Technician B stated that if excess oil is consumed, then it indicates that the PCV system is blocked. Which of the following statements is true in this scenario?
Both technician A's and B's assessments are accurate.
The PCV system controls which exhaust emission(s)?
HC and CO
The AIR system is used on vehicles to reduce ________ emissions.
Hydrocarbon
Which of the following is true of positive crankcase ventilation (PCV) tests?
In the 3 × 5 card test, if the card does not stay over the oil-fill opening it means that the PCV valve needs inspection.
Technician A says that a PCV valve that rattles when removed should be replaced. Technician B says that a PCV valve that rattles when removed is OK and can be reused. Who is correct?
Neither technician A nor B
Two technicians carry out the crankcase vacuum test on a positive crankcase ventilation (PCV) system. They connect a water manometer to a dipstick tube and observe the gauge at idle and at 2,500 RPM. The gauge does not show any vacuum at idle or at 2,500 RPM. Technician A states that the PCV system is blocked. Technician B states that the PCV system is working fine. Which of the following statements is true in this scenario?
Only technician A's assessment is accurate.
Two technicians test a secondary air-injection (SAI) system by using an exhaust gas analyzer. They record the O2 reading after shutting off airflow to the SAI system. They then allow air to flow through the SAI system and note that the O2 level has increased by 3%. Technician A states that the SAI system is faulty because the O2 level has to increase by 10%. Technician B states that the system is functioning correctly. Which of the following statements is true in this scenario?
Only technician B's assessment is accurate.
The diagnostic trouble code for a mass airflow (MAF) circuit fault is given by ________.
P0101
Which of the following is true of positive crankcase ventilation (PCV) valves?
PCV valves usually are located in the valve cover or intake manifold.
Technician A says that the PCV system should create a slight pressure in the crankcase at idle. Technician B says that the PCV system should create a slight vacuum in the crankcase at 2500 RPM. Which technician is correct?
Technician B
Which of the following is true about crankcase ventilation?
The fuel-injected engine uses an oil/vapor separator instead of a valve.
The process of gases and unburned fuel leaking past the piston rings from the combustion chamber is called ________.
blowby
The secondary air-injection (SAI) system helps reduce ________.
carbon monoxide (CO)
Extra air helps to oxidize unburned hydrocarbons (HC) and carbon monoxide (CO) into water vapor (H2O) and carbon dioxide (CO2) in the ________.
catalytic converter
A(n) ________ contains a spring-type metallic disc or reed that closes under exhaust back pressure.
check valve
In an orifice-controlled type of positive crankcase ventilation (PCV) system, the orifice is least likely to be located in the ________.
crankcase
where is the output of the AIR pump directed when the engine is cold?
exhaust manifold
All positive crankcase ventilation (PCV) systems use a PCV valve or calibrated orifice and a(n) ________.
inlet air filter
A(n) ________ is a possible cause for the diagnostic trouble code P0410.
loose or corroded electrical connection
A secondary air-injection (SAI) pump is also called a ________.
smog pump
When checking the PCV system at the dipstick tube, what should the technician lookfor?
some vacuum
The switching valves on the AIR pump have failed several times. Technician A says that a defective exhaust check valve could be the cause. Technician B says that a leaking exhaust system at the muffler could be the cause. Which technician is correct?
technician A
Technician A says that if a PCV valve rattles, then it is okay and does not need to be replaced. Technician B says that if a PCV valve does not rattle, it should be replaced. Which technician is correct?
technician B
Two technicians are discussing exhaust check valves used in SAI systems. Technician A says that they are used to prevent the output from the SAI pump from entering the intake manifold. Technician B says the check valves are used to keep the exhaust from entering the AIR pump. Which technician is correct?
technician B
How much of the air needed by the engine flows through the PCV system when the engine is at idle speed?
up to 30%
The ________ test is done by placing a finger over the inlet hole in a valve when an engine is running, and removing the finger rapidly.
snap-back
