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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