Engine Performance Final Questions and Answers with Verified Solutions

Engine Performance Final Questions and Answers with Verified Solutions 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? d. neither A nor B Ignition spark typically occurs a few degrees _______. a. before top dead center (BTDC) Which of the following is NOT an advantage of an electronic spark control system? b. It allows lower compression ratio engines to be as efficient as higher compression ratio engines 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? d. neither A nor B The first decision the computer makes in determining the best operating strategy is to determine the _____. b. engine operating mode 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. B only What sensor is used to detect engine misfire? a. crankshaft position 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? c. 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? c. 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? c. both A and B To read flash codes on an OBD I Chrysler-built vehicle, you must ______. d. turn the ignition key on and off three times in five seconds, ending with on Which of the following sensors is NOT used by the computerized ignition system to control ignition timing? a. oxygen sensor OBD II technology is being discussed. Technician A says the OBD II system has the ability to store a freeze frame (snapshot) of the operating conditions that existed when the fault occurred. Technician B says vehicle identification must be transmitted automatically to the scan tool. Who is correct? c. Both A and B Which of the following does NOT use a magnetic pulse generator [PM generator]? b. throttle position sensor The engine coolant temperature sensor helps to control all the following EXCEPT: a. fuel pressure 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? c. both A and B A conventional oxygen sensor needs to be heated to ________ degrees Fahrenheit before it can produce a usable signal. b. 750 Which of the following problems would NOT cause a oxygen sensor to appear bad? d. leaking muffler to tailpipe gasket Which of the following tools cannot be used to test an oxygen sensor? b. analog voltmeter A throttle position sensor has ______. a. a 5-volt reference input terminal An accelerator pedal position sensor (APP) is used on vehicles equipped with ______. a. electronic throttle control Which of the following is NOT an actuator? a. PCV valve Which of the following is a component of the secondary ignition circuit? spark plug Reach, heat range, and air gap are all characteristics that affect the performance of which ignition system component? spark plugs 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 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? c. 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 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 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 spark plugs are part of the primary ignition circuit. Technician B says the battery is part of the secondary ignition circuit. Who is correct? neither A and B Which of the following components is part of both the primary and secondary ignition circuits? ignition coil 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. W