FUEL SYSTEMS TEST 3
While discussing EGR valve diagnosis, Technician A says that if the EGR valve does not open, the engine may hesitate on acceleration. Technician B says that if the EGR valve does not open, the engine may detonate on acceleration. Who is correct?
B only
Technician A says that HCs result from unburned fuel and from incomplete combustion. Technician B says that CO is formed with a mixture that is too rich. Who is correct?
Both technicians
Technician A says that PCV systems are used to relieve engine blow-by pressure. Technician B says that PCV systems also control sludge. Who is correct?
Both technicians
Technician A says that canister purging occurs only when conditions are right. Technician B says that modern purge valves are computer controlled. Who is correct?
Both technicians
Technician A says that a desired backpressure reading is 1.25 psi or less. Technician B says that anything less than 2.75 psi is acceptable. Who is correct?
A only
Technician A says that the computer monitors the operation of the catalytic converter by looking at the upstream and downstream oxygen sensors. Technician B says that a vacuum gauge installed on a manifold vacuum source will rise steadily on hard acceleration if the exhaust is restricted. Who is correct?
A only
While discussing catalytic converter operation, Technician A says a delta temperature test should be conducted. Technician B says a good converter will have an outlet that is 8 percent cooler than the inlet. Who is correct?
A only
While discussing digital EGR valve diagnosis, Technician A says that a scan tester may be used to command the PCM to open each solenoid in the EGR valve. Technician B says that the EGR valve should open when 18 in. Hg of vacuum are supplied to the valve at idle speed. Who is correct?
A only
While discussing PCV system diagnosis, Technician A says that an accumulation of oil in the air cleaner indicates the PCV valve is stuck open. Technician B says that an accumulation of oil in the air cleaner may indicate the piston rings and cylinders are worn. Who is correct?
B only
While discussing a linear EGR, Technician A says that the commanded pintle position and the actual pintle position have to be the same. Technician B says that the pintle position at idle cannot exceed 3 percent. Who is correct?
B only
Technician A says that improper canister purge will cause an engine to run rough in hot weather. Technician B says that the ORVR system is part of the evaporative emissions system. Who is correct?
Both A and B
While discussing EGR systems, Technician A says that a too high TP sensor signal may cause the EGR to open early. Technician B says that DTCs from other sensors can assist in diagnosing EGR failures. Who is correct?
Both A and B
While discussing EGR valve diagnosis, Technician A says that a defective throttle position (TP) sensor may affect the EGR valve operation. Technician B says that a defective engine coolant temperature (ECT) sensor may affect the EGR valve operation. Who is correct?
Both A and B
While discussing EVAP valves, Technician A says the evaporative emissions system must be able to detect a leak as small as 0.020 inches in size. Technician B says that the monitor for the EVAP system works by closing the purge and vent valves and watching to see if the tank pressure increases. Who is correct?
Both A and B
While discussing PCV system diagnosis, Technician A says that a defective PCV valve may cause rough idle operation. Technician B says that satisfactory PCV system operation depends on a properly sealed engine. Who is correct?
Both A and B
While discussing knock sensor and knock sensor module diagnosis, Technician A says that with the engine running at 1,500 rpm, if the engine block is tapped near the knock sensor, a knock sensor signal should appear on the scan tester. Technician B says that with the engine running at 1,500 rpm, if a 12-volt test light is connected from a 12-volt source to the disconnected knock sensor wire, a knock sensor signal should appear on the scan tester. Who is correct?
Both A and B
While discussing knock sensors, Technician A says that the first thing to check is the system's wiring and connections for corrosion or looseness. Technician B says that the knock sensor has one purpose, to control spark knock. Who is correct?
Both A and B
Technician A says that CARB is an abbreviation for California Air Resources Board. Technician B says that PMVI is to inspect a vehicle's emission controls twice a year. Who is correct?
Technician A
Technician A says that NOx is formed at temperatures over 2,500°F. Technician B says that NOx is formed when an engine overcools, due to a stuck open thermostat. Who is correct?
Technician A
Technician A says that lower compression ratios bring down NOx emissions. Technician B says that lower compression ratios improve performance and fuel mileage. Who is correct?
Technician A
Technician A says that EGR systems reduce the amount of HC emission. Technician B says that EGR systems use controlled amounts of exhaust gases to cool combustion temperatures. Who is correct?
Technician B
Technician A says that if gasoline is allowed to evaporate into the air, it becomes a significant source of CO emissions. Technician B says that before evaporative emission (EVAP) controls, 20 percent of the total emissions from a vehicle occurred while it was sitting in the driveway. Who is correct?
Technician B
Technician A says that most manufacturers started adding controls to reduce oxides of nitrogen (NOx) as early as 1960. Technician B says that the first catalytic converters were designed to oxidize CO and HC. Who is correct?
Technician B
All of the following are pre-combustion emission controls except
catalytic converter
IM240 and RG240 tests are basically the same except
they use the same type of chassis dyno