Automotive 155 Final
Which of the following statements is NOT true?
A conventional oxygen sensor receives a 5-volt reference voltage from the PCM.
Which of the following is NOT a type of mass airflow sensor?
Hall effect
Which of the following is NOT an advantage of an electronic spark control system?
It allows lower compression ratio engines to be equally as efficient as higher compression ratio engines
Reach, heat range, and air gap are all characteristics that affect the performance of which ignition system component?
spark plugs
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
To read flash codes on an OBD I Chrysler-built vehicle ______.
turn the ignition key on and off three times in five seconds, ending in on
The stroke of an engine is _____ that of a crankshaft throw.
twice
A four-stroke cycle engine requires at least _____ valves at the top of each cylinder.
two
On an OBD-II vehicle, the DLC connector is located _____.
under the dashboard, within arm's reach of the driver
A wet compression test is performed on an engine after a dry compression test revealed low compression on one cylinder. If the compression on the low cylinder rises, it indicates _____.
worn rings
What type of ICE engine listed below is commonly found in a hybrid vehicle.
Atkinson
In what type of engine is the intake valve held open longer than normal during the compression stroke?
Atkinson cycle
A technician is rebuilding an engine and notices that one tooth is missing from the crank sensor pulse ring. Technician A says the pulse ring is broken and will have to be replaced. Technician B says that missing tooth identifies when cylinder #1 is at TDC and that the missing tooth is normal. Who is correct?
B only
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
A vehicle with a DTC for an engine coolant temperature out of range code is being tested.The serial data stream shows the coolant temperature to be 198 degrees Fahrenheit. When the technician tests the resistance between the ETC terminals, he finds infinite resistance. The specifications call for 20 to 40 ohms at 200 degrees Fahrenheit. After the ECT is replaced and the code is erased, the system runs normally and the code and MIL illumination do not reoccur. How is this possible?
When the ECT failed, the PCM substituted a nominal ECT value that allowed the engine to run in limp home mode; the substituted value was displayed by the scan tool
A throttle position sensor has ______.
a 5-volt reference input terminal
The heat range of a spark plug is indicated by ______.
a code within the plug number imprinted on the side of the spark plug
All the following elements except _____ are used in the spark plug center electrode to increase plug life.
cesium
How many degrees of crankshaft rotation does it take to complete one complete engine cycle in a 4-stroke engine?
720
To complete a four-stroke cycle in one cylinder, the crankshaft must rotate _____ degrees.
720
A conventional oxygen sensor needs to be heated to ________ degrees Fahrenheit before it can produce a usable signal.
750
A technician connects a DMM with a MIN/MAX/AVG function to the output of an oxygen sensor. The engine is run at 2000 RPM for several minutes. During the test, the voltage toggles rapidly between 150 and 900 millivolts. At the end of the test, the MAX voltage was .967 V, the MIN voltage was .087 V, and the AVG voltage was .683 V. Technician A says the sensor is faulty and should be replaced. Technician B says there could be a vacuum leak that caused the sensor voltage to have a higher than normal average. Who is correct?
A only
Technician A says the engine displacement can be found on the engine ID tag. Technician B says the date the engine was assembled can be found in the casting numbers on the cylinder block. Who is correct?
A only
Technician A uses the snapshot function of his scan tool to record serial data during a road test that can be transferred and displayed on a PC. Technician B uses the snapshot feature of his scan tool to record the sensor data and conditions leading up to the vehicle setting a DTC. 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
Two technicians are discussing OBD-II monitor readiness status. Technician A says that the vehicle must be driven through a drive cycle that includes several minutes of idle, low-speed cruise, medium-speed cruise, and deceleration before all monitors can be performed. Technician B says all monitors can be performed in five minutes of fast idling. Who is correct?
A only
Which of the following statements is not true?
A type B misfire will cause the MIL light to flash
Coil-over-plug ignition systems are being discussed, Technician A says COP coils have less time between each firing cycle, which increases the heat in the coil and can cause premature failure. Technician B says the COP system allows the ignition timing for each cylinder to be individually changed for maximum performance as the system responds to knock sensor signals. Who is correct?
B only
Computer-controlled ignition timing is being discussed. Technician A says when excessive wheel slippage occurs, the PCM will advance the timing to increase the torque output from the engine. Technician B says to provide smooth shifting of an automatic transmission, the PCM will temporarily retard the ignition timing to reduce the engine's torque when the transmission is beginning to change gears.
B only
Crankshaft sensors are being discussed. Technician A says the signal from a Hall-effect CKP cannot be used to synchronize fuel injector timing with the engine. Technician B says some early distributor ignition systems relied on photoelectric sensors to monitor crankshaft position. Who is correct?
B only
Diagnostic trouble codes are being discussed. Technician A says a P0442 is a manufacturer's code and means different things, depending on what manufacturer built the car. Technician B says that a P0304 code is a universal code that means the same thing no matter what manufacturer built the car. Who is correct?
B only
Spark plug design is being discussed. Technician A says a plug with too short a reach makes it difficult to attach the plug wire boot. Technician B says a plug with too long a reach may cause preignition. Who is correct?
B only
Technician A says a plug with a V-notch ground electrode will have two electric arcs jumping across the spark plug gap each time the spark plug fires. Technician B says a spark plug gap that is too wide requires higher voltage to jump the gap, which can cause a misfire. Who is correct?
B only
Technician A says engine displacement is commonly measured in cubic millimeters. Technician B says it is commonly measured in cubic inches. Who is correct?
B only
Two technicians are discussing compression testing on a hybrid vehicle equipped with an Atkinson cycle engine. Technician A says the compression reading of an Atkinson cycle engine is normally higher than a conventional engine. Technician B says a scan tool may be needed to perform the compression test. Who is correct?
B only
A vehicle towed into the shop with a "cranks but doesn't start" problem. A quick check under the hood reveals that the spark plugs are not firing and the injectors are not receiving a pulse from the PCM. The technician notices that the MIL light does not come on when the key is turned to the run position. What would you do next?
Check the PCM's fuses, power wires, and ground wires
The two types of ignition systems are EI [electronic ignition] and ______.
DI [distributor ignition]
A MAP sensor with a varying frequency output can be tested with a(n) ______.
DMM with a frequency function
Which V-type engine valve train design may use four camshafts?
DOHC
Which of the following is NOT an actuator?
PCV valve
Data collected by system sensors is stored in _____ memory.
RAM
Which statement is NOT true?
Some sensors are solenoids
A phaser is used to _____.
advance or retard camshaft timing
A camshaft position sensor provides the PCM with data needed to control _____.
all answers are correct
An air/fuel ratio sensor is different from an oxygen sensor in that ______.
all answers are correct
Oxygen sensors may become contaminated by ______.
all answers are correct
Which of the following tools should not be used to test an oxygen sensor?
analog voltmeter
Ignition spark typically occurs a few degrees _______.
before top dead center [BTDC]
A technician is setting up a lab scope to measure a sensor. Technician A says that the vertical voltage scale must be adjusted in relation to the expected voltage signal. Technician B says the trigger slope must be set to positive if the trace begins with a rising voltage. Who is correct?
both A and B
Before performing any repairs on a vehicle with an illuminated MIL light: Technician A records all DTCs and freeze frame data. Technician B checks for service bulletins.Who is correct?
both A and B
Diesel engines are being discussed. Technician A says diesel engines have a distributor-type injection pump. Technician B says diesel engines have a common fuel rail and the injectors are controlled by the computer. 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 flowing through the EGR valve. Who is correct?
both A and B
Engine operating modes are being discussed. Technician A says that when the engine is in closed-loop mode, the PCM monitors sensor inputs, then adjusts the timing, air fuel ratio, and emission controls. Technician B says the system will switch into open loop when the throttle is fully opened or the oxygen sensors cool down during idle. 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
Front engine, longitudinal layout is being discussed. Technician A says this layout is used in rear-wheel drive vehicles. Technician B says this layout is used in some front-wheel drive vehicles. Who is correct?
both A and B
Ignition coils are being discussed. Technician A says the primary coil is normally composed of 100 to 200 turns of 20-gauge wire. Technician B says the secondary coil consists of 15,000 to 25,000, or more, turns of very fine copper wire. Who is correct?
both A and B
Ignition timing is being discussed. Technician A says when the engine idle speed moves away from the desired idle speed, the PCM will adjust the timing to stabilize the engine speed. Technician B says when a knock is detected, the PCM retards the timing in fixed steps until the knock disappears. Who is correct?
both A and B
In EI systems using one ignition coil for every two cylinders, Technician A says two plugs fire at the same time, with one wasting the spark on the exhaust stroke. Technician B says one plug fires in the normal direction and the other in reversed polarity. 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
Resistor-type spark plugs are being discussed. Technician A says the resistor increases the plug firing voltage. Technician B says the resistor helps reduce radio frequency interference [RFI], which can interfere with, or damage, radios, computers, and other electronic accessories, such as GPS systems. Who is correct?
both A and B
Technician A says a magnetic pulse generator type sensor generates a small AC voltageeach time one of the machined slots in the trigger wheel passes by. Technician B says some ignition systems use dual Hall-effect sensors that produce a 3x and 18x/revolution pulse. Who is correct?
both A and B
Technician A says spark plugs are part of the secondary ignition circuit. Technician B says the battery is part of the primary ignition circuit. Who is correct?
both A and B
Technician A says weak valve springs can be detected with a vacuum test. Technician B says a restricted exhaust can be detected with a vacuum test. Who is correct?
both A and B
Technician A tests an MAF sensor with a scan tool by watching for erratic changes in flow while the engine idles. Technician B checks an MAF sensor by tapping it lightly with the handle of a screwdriver while watching the waveform on a lab scope. Who is correct?
both A and B
Two technicians are discussing IAT sensors (intake air temperature). Technician A says the IAT sensor is an integral part of the mass airflow sensor (MAF). Technician B says the IAT is a discrete sensor located in the intake air passages or air cleaner assembly. Who is correct?
both A and B
Two technicians are discussing diesel engines. Technician A says all diesel engines are fuel injected. Technician B says glow plugs help ignite the fuel when the engine is cold. Who is correct?
both A and B
Two technicians are discussing testing switch type sensors. Technician A uses an ohmmeter. Technician B uses a voltmeter. Who is correct?
both A and B
The device that protects the PCM and other electronic components from the voltage spike created in the windings of a solenoid, relay, or magnetic clutch when they are turned off is called a ______.
clamping diode
Which of the following engine problems may be indicated by good results from a compression test and a cylinder leakage test but poor results from a cylinder power balance test?
collapsed lifter
Both valves are closed on the _____ strokes.
compression and power
The volume of the combustion chamber when the piston is at BDC divided by the volume of the chamber when the piston is at TDC is called _____.
compression ratio
What component of the engine determines the stroke?
crankshaft
The reciprocating movement of the piston is converted into rotary motion by the _____.
crankshaft and connecting rod
What sensor is used to detect engine misfire?
crankshaft position
In a GDI system (gasoline direct injection) the injector sprays fuel into the ______.
cylinders (combustion chamber)
An accelerator pedal position sensor (APP) is used on vehicles equipped with ______.
electronic throttle control
Which of the following jobs is NOT a function of the ignition system?
engaging the starter motor
The first decision the computer makes in determining the best operating strategy is to determine the _____.
engine operating mode (cranking, idling, cruise, etc.)
The component connected to the crankshaft that serves to store some of the engine's power is the _____.
flywheel
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 the following EXCEPT:
fuel pressure
When the cylinders are deactivated on a displacement on demand system, _____.
half of the cylinders continue to fire normally
Which one of the following is NOT a stroke of the four-stroke cycle?
ignition
Which of the following tools should not be used to test an actuator unless the technician is directed to do so by the manufacturer's service procedures?
jumper wires
Which of the following problems would NOT cause a oxygen sensor to appear bad?
leaking muffler to tailpipe gasket
When the system is running rich, the oxygen content in the exhaust is ______.
low
Air/fuel ratios are being discussed. Technician A says that when the air fuel ratio is higher than 14.7 to 1 the engine produces more power. Technician B says that when the air fuel ratio is lower than 14.7 to 1 the engine uses less fuel. Who is correct?
neither A nor B
EI systems are being discussed. Technician A says a waste spark system has one coil per cylinder. Technician B says a coil-on-plug system uses a double-ended coil. Who is correct?
neither A nor B
Engine oil pressure testing is being discussed. Technician A says that oil pressure should be tested with the engine cold. Technician B says oil with viscosity that is too high may cause lower than specified pressure. Who is correct?
neither A nor B
Engine vacuum is being discussed. Technician A says that when the engine is operating under light loads, engine vacuum is low. Technician B says that engine vacuum is high when the engine is operated under heavy loads. Who is correct?
neither A nor B
Resistor plugs are being discussed. Technician A says that if the original equipment resistor plugs are replaced with nonresistor plugs, the engine will produce more power at high RPM. Technician B says that if the original equipment resistor plugs are replaced with nonresistor plugs, the engine will run smoother at low RPM. Who is correct?
neither A nor B
Spark plug wires are being discussed. Technician A says silicon-insulated wires are used for normal temperature applications. Technician B says hypalon-insulated wires are used for high-temperature applications. Who is correct?
neither A nor B
Which of the following chemicals is NOT a pollutant?
nitrogen [N2]
What is compression ratio?
none of these answers is correct
Which of the following sensors is NOT used by the computerized ignition system to control ignition timing?
oxygen sensor
On a 4-cylinder engine that has a firing order of 1342, if number 1 cylinder is on the exhaust stroke, what stroke is number 3 cylinder on?
power
Modern ignition cables contain carbon fiber cores that act as a(n) ____ in the secondary circuit to cut down on radio and television interference and reduce spark plug wear.
resistor
One of the advantages of a coil-on-plug type ignition system is that it eliminates the need for ______.
spark plug wires