ASE - Engine Performance Questions and Answers Graded A+

ASE - Engine Performance Questions and Answers Graded A+ Magnetic pulse generators are used to provide a digital signal about component speed or position. False A digital signal may be called a square-wave signal. True The manifold absolute pressure (MAP) sensor monitors engine load. True A defective O2 sensor heater may cause reduced open loop time. False A defective vehicle speed sensor may cause improper torque converter lockup. True A vehicle with throttle actuator control may use three throttle position sensors. True The exhaust gas recirculation valve position sensor is a linear potentiometer mounted on top of the EGR valve. True The knock sensor changes vibration to a frequency signal and sends the signal to the computer. False Many modules have to be reprogrammed for the vehicle if they are to be replaced. True Engines that have throttle actuator control require an idle air control motor. False When checking a solenoid with an ohmmeter, there should be an infinity reading on the meter if the solenoid is good. False If the computer activates a component or circuit by completing a ground it is referred to as a feed side driver. False The idle air control motor works by varying the position of the throttle plate. False The digital EGR is comprised of three solenoids that all flow different amounts of EGR. True Many modern engines do not have adjustable ignition timing. True Networking smaller more specialized modules is more cost effective than using one or two centralized complex modules. True The individual modules in a CAN system are sometimes called nodes. True Modules on the serial bus that can initiate communication with other modules on the serial data bus are called slaves. False A hot-range spark plug has a shorter heat path than a cold-range spark plug. False The ignition system contains two electrical sides, the primary and the secondary. True The secondary coil winding contains two hundred turns of heavy wire. False Base or initial timing is timing with computer advance added. False The ignition coil is both a primary and secondary ignition component. True Base timing is often adjustable on DI systems. True Ignition cables are usually made of solid wire which acts as a resistor in the secondary circuit. False Carbon tracking is the formation of carbonized dust between distributor cap terminals. True At increased RPM and less time between coil firings, electronic dwell begins earlier to allow for coil saturation. True The parade pattern on an oscilloscope displays cylinder patterns from right to left. False The triggering device in an electronic ignition system is used to indicate crankshaft position. True Waste spark system deliver spark to two cylinders at once. True One type of fast start electronic ignition system uses two crankshaft position sensors. True On most electronic ignition systems base timing needs to checked and adjusted whenever the system is serviced. False The camshaft position sensor may have to timed to the engine when it is installed. True A shorted secondary coil winding provides an ohmmeter reading above the specified resistance. False A shorted ignition coil may damage the ignition module. True Spark plugs with iridium tips should not be re-gapped. True PIP stands for profile ignition pickup. True In a waste spark system the spark plugs are connected in parallel to the ignition coils. False Piezoresistive sensors measure: pressure and mechanical strain. A burn-off relay may be used with which sensor? MAF sensor Short-term fuel trim (STFT) adds or subtracts fuel to correct for: Both B and C A low voltage signal from the O2 sensor indicates: A lean air/fuel ratio An O2 sensor may be used to: Both A and C. When a computer has adaptive strategy, a short learning period will be necessary when: All of the above. While accessing diagnostic trouble codes on a pre-OBD II vehicle: All of the above A breakout box is used to: Monitor signals received by the computer. Higher than normal reference voltage is recorded at a sensor. Which is the most likely cause? Excessive resistance in the voltage reference ground circuit. A defective engine coolant temperature may cause: All of the above A thermistor is a solid-state variable resistor made from a semiconductor material that changes resistance in relation to: temperature changes The computer uses the TP sensor to: Both A and B The oxygen sensor that changes current flow to indicate exhaust oxygen content is the: air-fuel ratio sensor Magnetic pulse generators are commonly used to send data to the computer about: The speed of the monitored component The computer may use the manifold absolute pressure sensor to: All of the above An engine stalls during tight parking maneuvers. Which is the most likely cause? Defective power steering switch Technician A says the PCM supplies power and ground to magnetic pulse generators. Technician B says the PCM supplies power and ground to Hall-effect sensors. Who is correct? Technician B Magnetic pulse generators can be checked by which of the following: All of the above All of the following are types of mass air flow sensors except: variable reluctance-type sensors Excessive oxygen in the exhaust gas stream will cause a zirconia oxygen sensor to: stay below 450mv Technician A says the computer may activate a circuit by completing the path to ground. Technician B says the computer may activate a circuit by completing the path to power. Who is correct? Both technicians are correct. Technician A says a quad driver has four independently controllable outputs. Technician B says some output driver modules may control up seven independent outputs. Who is correct? Both technicians are correct. Technician A says CAN network modules can share information with other modules on the same bus. Technician B says the CAN class A bus is for high speed data. Who is correct? Technician A In a CAN network, if a module fails to "check in" with the other modules: A trouble code is set Modules that are not part of any vehicle network are called: Stand alone modules While discussing the Ford Electronic Automatic Temperature Control Module system Technician A says: The Ford Electronic Automatic Temperature Control Module is completely responsible for operating the air conditioning system. Technician B says: The PCM has the last word on whether the air conditioning system will be allowed to operate. Who is correct? Technician B If a technician uses a scan tool to open the EGR valve while the engine is at idle: Both A and B After 2008 the only communication standard that can be used is: CAN Technician A says pulse width modulation is the duration of on time, but not connected to a specific cycle time. Technician B says duty cycle is measured in percentages Who is correct? Both technicians are correct. Which type of fuel injector has a relatively high current applied to quickly open the pintle, then the current is reduced to lower level. Peak and hold injectors The Ford lighting control module takes care of: All of the above The front passenger door module is a slave module which can: Communicate with other modules on the main serial bus UART, J1850, KWP 2000 and ISO 9141 are: Different computer networking languages. Technician A says each module in a CAN system receives every communication on the serial data bus. Technician B says only the messages with the correct heading are responded to by a module in a CAN system. Both technicians are correct. Bi-directional control means: The technician can tell a computer to exercise an output Technician A says an open in star network bus will affect all the modules on the network. Technician B says an open in a loop network will isolate a module from the network. Neither A or B The components of the PCM responsible for controlling circuits or devices are called: Drivers All of the following are PCM actuators except: PCV valve All of the following are the same communication protocol except: ISO 9141 All are benefits of the CAN network standard except: Consumes more power Technician A says the magnetic pick-up may be tested using a voltmeter to measure the AC voltage during cranking. Technician B says the Hall-effect sensor produces a square wave pattern on an oscilloscope. Who is correct? Both technicians are correct. Technician A says to adjust base timing on a distributor ignition system, the distributor housing is rotated. Technician B says on a Ford vehicle with a TFI IV ignition system, the SPOUT connector must be disconnected to check base timing. Who is correct? Both technicians are correct. The raster pattern on an oscilloscope displays cylinder patterns: Stacked one above the other. Base timing is the initial timing specified by the: manufacturer. Technician A says if the firing voltage is higher than normal the burn time will decrease. Technician B says if the firing voltage is lower than normal the burn time will decrease. Who is correct? Technician A Technician A says one component of the secondary ignition circuit is the coil. Technician B says the coil is a component in the primary ignition circuit. Who is correct? Both technicians are correct. In addition to ignition control, a Hall-effect switch can also be used to: Both A and B The firing voltages of a four cylinder engine are as follows: #1: 8kV; #2: 27kV; #3: 4kV; and #4: 9kV. Which of the following is true? Cylinder #2 may have an open plug wire. Ignition modules control: The ground connection to the primary coil winding. The ignition switch, primary winding, and module are all components of: The primary ignition circuit. Technician A says as engine speed slows, the timing should be retarded or have less advance. Technician B says typically, the more load on an engine, the less spark advance is needed. Who is correct? Both technicians are correct. The switching device in the ignition system is sometimes referred to as a: Ignition control module Which of the following could cause a weak spark condition? All of the above. Which of the following represents the amount of voltage necessary to sustain the spark across the spark plug gap? spark voltage An oscilloscope test shows firing lines the same, but abnormally high. This is the result of: A lean air/fuel mixture. Technician A says ignition coil primary voltage can reach 400 volts when the secondary ignition fires. Technician B says high voltage in the coil primary indicates a faulty ignition module. Who is correct? Technician A For maximum engine power to be obtained, maximum cylinder pressure should occur: 10 - 20 after TDC Technician A says the ignition timing must be fully advanced when the engine is operating at maximum load. Technician B says ignition timing is retarded under maximum load. Who is correct? Technician B The time during which current flows through the primary coil winding is called: Dwell All of the following situations may call for timing advance except: Heavy engine load Which of the following is not part of the primary circuit? Spark plugs A vehicle has a no-spark condition on a waste spark ignition system. Technician A says the crankshaft position sensor may need to be replaced. Technician B says the ignition module could be faulty. Who is correct? Both technicians are correct. The resistance of the primary winding of an ignition coil is typically: less than 2 ohms. Technician A says in a Ford electronic ignition system the profile ignition pick-up sensor is used to monitor camshaft position. Technician B says a cylinder identification sensor is used to monitor crankshaft position in a Ford electronic ignition system. Who is correct? Neither technician is correct. Technician A says some EI systems fire two spark plugs at each cylinder. Technician B says In Ford's dual plug system only one spark plug is fired in each cylinder during engine start-up. Who is correct? Both technicians are correct. A Hall effect switch can be checked with all of the following except: an AC voltmeter. On a Ford EI system, the wire that the PCM uses to control spark timing is: the SPOUT wire. The crankshaft speed signal on a Ford EI system is provided by the: PIP wire. A Hall effect switch is being analyzed on a lab scope. The high part of the signal measures 5.0 volts. Ideally, what should the low part of the signal read? 0.0 volts The secondary winding resistance of an EI ignition coil indicates 1.5 ohms. Technician A says the coil should be replaced. Technician B says the coil winding is shorted. Who is correct? Both technicians are correct. The GM Northstar engine uses: two crankshaft sensors and one camshaft sensor. Technician A says in a COP system the PCM can adjust ignition timing for each individual cylinder. Technician B says firing order in a COP system is controlled by the IC modules. Technician A The camshaft position sensor in a GM fast start system is used to: Sequence the injectors properly. On a COP equipped engine, if the crankshaft sensor becomes shorted: All of the above. Which statement is true about companion cylinders. When one cylinder is on the exhaust stroke the other is on the compression stroke. In an ion sense ignition system, information about the combustion chamber is determined by the: Spark plug Which of the following is not a standard location for a camshaft position sensor? On the flywheel Crankshaft position sensors are located in each of these places except: In the cylinder head All of the following are advantages of EI systems except: Decreased coil saturation A waste spark ignition system fires cylinders on which two strokes? Exhaust and compression If the O2 sensor voltage signal is higher the specified, the air/fuel ratio may be rich or the sensor may be contaminated There are two styles off vane air flow sensors. In the latest type the voltage should ____________________ as the vane is opened, in the earlier style the voltage should ____________________ as the vane is opened. decrease, increase The MAF sensor frequency should change smoothly and gradually in relation to ____________________. engine speed A Ford MAP sensor will normally have a frequency of ____________________ at sea level with no vacuum applied to the sensor. 155 hertz A malfunctioning ____________________ sensor may cause acceleration stumbles, engine stalling, and improper idle speed. throttle position KOEO stands for ____________________. Key On Engine Off A negative temperature coefficient thermistor ____________________ its resistance as temperature increases. decreases Prior to the implementation of OBD II, each car manufacturer required a different method for retrieving stored ____________________ from the computers memory. diagnostic trouble codes Digital devices will not operate with ____________________ voltage inputs. variable To access diagnostic trouble codes on an OBD I Chrysler product, without starting the engine, turn the ____________________ on and off three times within five seconds, ending with it on. ignition key The modules in a network have to use a common ____________________, or language. communication protocol ____________________ module communication is used for modules capable of initiating communication on the serial data line. peer to peer A fuel injector is actually a ____________________. solenoid Increasing an injectors on time ____________________ the amount of fuel delivered to the cylinders. increases The computer is in control of idle speed by varying the amount of ____________________ past the throttle plate with a stepper motor called the IAC. air The ____________________protocol is mandated for 2008 and newer vehicles for emissions related communication. controller area network A ____________________ has four independently controllable outputs. quad driver One way the PCM can control a large current with a smaller one is by using a ____________________. relay Output driver modules are capable of controlling up to ____________________ separate outputs 7 Vacuum operated EGR valves are controlled by a pulse width modulated ____________________. vacuum solenoid ____________________ is the precise position of the piston at the top of its travel in the cylinder. Top dead center The ignition coil works on the principle of magnetic induction to change 12 volts in the ____________________ circuit to 40,000 volts in the ____________________ circuit. primary, secondary The amount of time the coil is turned on is called ____________________ ____________________. dwell time ____________________ is the point of maximum current flow in the ignition coil's windings. Saturation The difference between the voltage required to jump the spark plug gap and the maximum available voltage of an ignition coil is referred to as secondary ____________________. reserve voltage In the Ford thick film integrated (TFI) IV ignition system, the signal from the Hall effect switch is referred to as the ____________________ signal. profile ignition pick-up The negative terminal of an ignition coil is commonly referred to as the ____________________ terminal. tachometer Spark duration is measured in ____________________. milliseconds If the coil polarity is ____________________ 20-40 percent more voltage is needed to fire the spark plugs. reversed Use an anti-seize compound on spark plugs installed in ____________________ cylinder heads. aluminum The primary ignition circuit current flow is controlled by the ____________________. ignition module Dual plug systems use two spark plugs per ____________________. cylinder The fast start electronic ignition system used in GM's Northstar system uses two ____________________ sensors. crankshaft position The Ford ____________________ signal is the spark out signal. SPOUT The best way to check for adequate spark in an ignition system is to use a ____________________. spark tester If the ____________________ sensor is mounted in the previous distributor opening, the sensor must be timed to the engine when it is installed. camshaft position The camshaft position sensor on an EI system typically provides information about the ____________________ cylinder. number one EST is controlled by the ____________________. PCM The falling side of a Hall effect switch signal is also referred to as the ____________________ side. trailing EI systems that does not use spark plug wires are called ____________________ systems. coil on plug, COP What type of sensor is used to indicate a yes-no or on-off condition. switch What is the purpose of the fuel tank pressure sensor in an EVAP system. check for leaks How should the PCM respond if the MAP sensor sends a signal indicating a heavy load condition? The PCM should respond by send a rich command to the fuel injectors when the MAP sensor indicates a heavy load condition What is the purpose of the exhaust gas recirculation valve position (EVP) sensor? The EVP sensor sends a signal to the PCM in relation to EGR valve opening. As the EGR valve opens the EVP sensor sends a higher voltage signal to the PCM. Explain how a knock sensor works. When the engine detonates, a vibration is present in the engine block and cylinder head castings. The knock sensor changes this vibration to a voltage signal and sends this signal to the PCM. Describe what will determine if a module will respond to a communication in a CAN system. A module in a CAN system will respond to a message if the message has the correct heading. Describe a slave module. A slave module can only listen to instructions from a master module and relay confirmation the instructions have been carried out. Describe a stand alone module. A stand alone module in not part of any network. What is the difference between a diagnostic message and a normal message in a CAN system? Diagnostic messages are the messages communicated to a scan tool and normal messages are those that go between modules. List three functions controlled by the driver door module. The power windows, power door locks, and remote keyless entry are controlled by the driver door module. Describe what could cause all of the firing voltage lines to be abnormally low on an oscilloscope display. A rich air/fuel mixture, breaks in the coil wire causing arching, cracked coil tower causing arching, low coil output, or low engine compression can cause all of the firing voltage lines to be abnormally low on an oscilloscope display. What can cause cold fouling of spark plugs? This condition is the result of an excessively rich air-fuel mixture or an ignition fault. Ignition dwell is described as: The length of time there is current flow in the primary circuit prior to firing the spark plug. Describe why ignition timing is advanced as engine RPM increases. At higher engine speeds, the crankshaft turns through more degrees during a given period of time. The ignition timing must be advanced to complete the combustion process at the same point of crankshaft rotation. What is the goal of computerized spark timing? The goal is to produce maximum engine power, top fuel efficiency, and minimum emissions levels in all types of operating conditions. What is indicated when the red and green lights on a logic probe are alternately flashing while connected to the negative side of the coil while cranking the engine This indicates that over 10 volts is available to the coil while cranking and that the circuit is switching to ground. What is the function of the camshaft position sensor in an electronic ignition system? The camshaft position sensor helps the computer determine when the number 1 piston is at TDC on the compression stroke. The computer uses this information to synchronize spark timing and fuel injection timing. What is the advantage of a fast-start EI system? Depending on the system version, fast-start EI systems are able to provide spark within 120 to 180 degrees of crankshaft rotation when the engine is being started. This is due to the more elaborate crankshaft and camshaft sensor configurations that are used by these systems. What is the function of Ford's Dual Plug EI system? Ford's Dual Plug system delivers spark to the two spark plugs per cylinder used by these four cylinder engines. During cranking, only one spark plug operates. What is the purpose of the triggering device in an electronic ignition system? The triggering device monitors crankshaft position which the computer uses to time the spark.