1st semester guides
Cylinder heads
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EMISSIONS
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What is typically the maximum amount of warpage that is acceptable on a cast-iron cylinder head?
0.004 in. (.102 mm)
A typical interference angle is _____ degrees
1
NOx emissions are caused by nitrogen and oxygen uniting at cylinder temperatures above_____
2,500 Fahrenheit (1,371 Celsius)
A conventional oxygen sensor needs to be heated to_____ degrees Fahrenheit before it can produce a usable signal.
750
Throttle position sensor has_____
A 5-volt reference input terminal
Technician A says heat is transferred from an exhaust valve to the cylinder head through the valve seat. Technician B says some exhaust valves have a hollow stem filled with silicone to transfer heat to the valve guide. Who is correct?
A only
Technician A says if valve stem height exceeds specifications, it can be adjusted by grinding the valve tip. Technician B says the valve stem height can be adjusted with shims. Who is correct?
A only
Technician A uses a 30 degree stone for topping a 45 degree valve seat. Technician B uses a 60 degree stone to lower a 45 degree valve seat. Who is correct?
A only
Trouble codes are being discussed. Technician a says that the first time the system detects a fault, a pending code is set. Technician B says that a pending code will turn on the MIL light. Who is correct?
A only
Cylinder head warpage can be measured with _____
A straight edge and feeler gauge
Which of the following statements is not true?
A type B misfire will cause the MIL light to flash
Diagnostic trouble codes are being discussed. Technician a says a P0442 is the manufactures code and means different things depending on what manufacture built the car. Technician B says the P0304 code is a universal code that means the same thing no matter what manufacture build the car. Who is correct?
B only
Technician A says the end of the valve spring that is wound the tightest should face toward the spring retainer. Technician B says the o-ring seal should be installed in the lowest of the keeper grooves on the valve stem. Who is correct?
B only
Technician A says the valve seats must be ground before the valve guides are serviced. Technician B says before grinding the valve seats, they should be checked for cracks. Who is correct?
B only
Technician A checks for bent pushrods by rolling them on a flat surface. Technician B checks for bent pushrods using a dial indicator and v-blocks. Who is correct?
Both A and B
Technician A resurfaces valve seats using a grinding stone. Technician B resurfaces valve seats using a cutting blade. Who is correct?
Both A and B
Technician A says multivalve engines can have three valves per cylinder. Technician B says multivalve engines can have five valves per cylinder. Who is correct?
Both A and B
Technician A says multivalve engines have a more complete combustion than conventional engine designs. Technician B says the benefits of multivalve engines are offset to some extent because a more complicated camshaft arrangement is needed. Who is correct?
Both A and B
Technician A says positive valve stem seal fit tightly around the top of the stem. Technician B says positive stem seals scrape oil off the valve as it moves up and down. Who is correct?
Both A and B
Technician A says worn valve stem seals can increase oil consumption. technician B says worn valve stem seals can cause valve deposits. Who is correct?
Both A and B
Which type of surfacing machine uses underside rotary cutters?
Broaching
Which of the following is not true of knurling
It is useful for restoring badly worn guides to their original condition
Which of the following problems would not cause the oxygen sensor to appear bad?
Leaking muffler to tailpipe gasket
When the system is running rich, the oxygen content in the exhaust is_____
Low
After resurfacing a valve seat at 45 degrees, the seat is too wide and the contact pattern extends all the way up to the valve margin. What should be done to bring the seat width into specifications?
Make a 30 degree topping cut
Engine vacuum is being discussed. Technician a says that when the engine is operating under light loads engine vacuum is low. Technician B says the engine vacuum is high when the engine is operated under heavy loads. Who is correct?
Neither A nor B
The exhaust gas recirculating system reduces_____
Oxides of nitrogen
Which one the following sensors is not used by the computerized ignition system to control ignition timing?
Oxygen sensor
Which of the following is not an actuator
PCV valve
A single hole in the cylinder head that divides into two branches is called a _____ port
Siamese
Which statement is not true?
Some sensors are solenoids
Which of the following tools is not used in testing engine sensors?
Test light
The injector pulse width is_____
The amount of time the injector opens and sprays fuel
Which of the following is not a PCM output?
Thermostats
A digital EGR valve has up to_____solenoids
Three
A catalytic converter is one of the most effective emission control devices on a vehicle for reducing HC, CO, and NOx emissions
True
A cylinder head may be made of cast iron or aluminum
True
A digital EGR valve contains up to three electric solenoids that are operated directly by the pcm
True
A misfiring spark plug can cause a false oxygen sensor reading
True
A three way catalytic converter [TWC] stores oxygen when the air/fuel ratio is rich
True
Aluminum cylinder head bolts should never be loosened or tightened when the metal is hot
True
Aluminum cylinder heads weigh roughly half as much as cast-iron heads
True
Aluminum expands and contracts almost twice as much as cast-iron in response to temperature changes
True
Carbon dioxide [CO2] is a greenhouse gas and may be the major cause of global warming
True
For most actuators, the circuit driver in the PCM applied a ground to the circuit to turn the actuator on and removes the ground to turn the actuator off
True
Hydrocarbon and carbon monoxide exhaust emissions are highest when the engine is cold
True
If the MIL light is on, there will be a DTC and associated freeze frame data stored in the PCM's memory
True
Lower compression ratios reduce NOx emissions
True
Many camshaft journals run directly on aluminum supports and do not use bearing inserts
True
NOx emissions increase as combustion temperatures increase
True
OBD-II regulations require all vehicle manufacturers to use the same names and acronyms for all electric and electronic systems related to the engine and emission control systems
True
OBD-II systems monitor the EVAP systems for leaks
True
Port fuel injection systems have throttle plate assembly, but fuel never passes by the plate
True
Re-surfacing a cylinder head gasket surface may alter the combustion chamber volume
True
Scan tools can be used to cycle on and off some actuators such as injectors, vacuum solenoids, idle air control motors, and the like
True
Some PCM inputs come from another control module through the vehicle network
True
Stainless steel is non magnetic
True
The PCM can turn off the A/C compressor when the engine is operating at full throttle
True
The performance of an engine it's fuel-efficiency and it's exhaust emissions all depend to a large extent on the shape of the combustion chamber
True
To protect Scuffing and wear some valves have coatings of black nitride applied to the valve stem
True
_____ type valve stem seals move up and down with the valve stems to deflect oil away from the guides
Umbrella
On an OBD-II vehicle, the DLC connector is located_____
Under the dashboard, within an arms reach of the driver
A camshaft position sensor provides the PCM with data needed to control_____
All answers are correct
Multiple valve engines tend to be more efficient than engines with two valves per cylinder because:
All answers are correct
Oxygen sensors may become contaminated by_____
All answers are correct
Resurfacing the cylinder head can affect_____
All answers are correct
To ensure proper seating of the valve, the valve seat must _____
All answers are correct
Valve guides are_____
All answers are correct
Which of the following tools cannot be used to test an oxygen sensor?
Analog voltmeter
Catalytic converter monitors are being discussed. Technician A says that if the converter is working, the downstream signal frequency should mirror the upstream sensor. Technician B says that the downstream sensor should provide a low-frequency voltage signal. Who is correct?
B only
The AIR system reduces_____
Both "hydrocarbons" and "carbon monoxide"
Which of the following can be reconditioned by grinding
Both "valve face" and "valve tip"
Before performing any repairs on a vehicle with an illuminated MIL light: technician a records all DTC's and freeze frame data. Technician b checks for service bulletins. Who is correct?
Both A and B
EGR monitors are being discussed. Technician A says some EGR system monitors EGR flow by measuring the difference in pressure as the EGR gas flows through an orifice (restriction). Technician B says some EGR monitors measure the temperature of the EGR outlet to determine whether there is gas through the EGR valve. Who is correct?
Both A and B
Freeze frame data is being discussed. Technician A says erasing the code with a scan tool will erase the corresponding freeze frame data. Technician B says the freeze frame data is the sensor and output status data at the instant the DTC was set. Who is correct?
Both A and B
Oxygen sensor monitors are being discussed. Technician A says the system monitors the sensor response time as the system cycles lean-rich-lean. Technician B says that at certain times the monitor varies the fuel delivery and checks for heated oxygen sensor response. Who is correct?
Both A and B
A MAP sensor with a varying frequency output can be tested with a_____
DMM with a frequency function
Which of the following systems is designed to reduce NOx
EGR
Induction-hardened integral valve seats are found on _____ cylinder heads
Cast iron
Prussian blue or machinist dye is used to _____
Check the width and position of the valve-to-seat contact pattern
Valve springs it should be checked for all of the following except
Compressed height
The first controlled automotive emission was_____
Crankcase vapors
What sensor is used to detect engine misfire?
Crankshaft position
A linear EGR valve contains up to three electric solenoids that are operated directly by the PCM
False
A sensor with a bad ground connection will produce a lower than normal signal voltage
False
An ignition misfire can cause excessive carbon monoxide emissions in the exhaust
False
During the EVAP monitor vacuum pull-down test, the canister vent solenoid is held open
False
Only OBD-II equipped vehicles have a sixteen-pin DLC connector
False
Powder metal valve seats are softer and do not last as long as cast iron seats
False
Sodium filled valves should be cut open for inspection
False
The engine coolant temperature sensor is typically found in the radiator
False
The hemispherical combustion chamber provides excellent turbulence to the air and fuel mixture
False
The resistance of the intake air temperature (IAT) sensor increases as air temperature increases
False
A per roof combustion chamber is normally found on a _____ type cylinder head
Four valve per cylinder
The sensor and output status data stored when a DTC is set is called_____
Freeze frame data
The engine coolant temperature sensor helps to control all of the following except:
Fuel pressure
_____emissions are caused largely by unburned fuel from the combustion chambers
HC
ENGINE PERFORMANCE
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