ASE 1 - Engine Performance(Questions And Answers)

2. A technician is checking for piston ring groove clearance. The proper technique includes A. The old ring and a feeler gauge. B. The new ring and a feeler gauge. C. Only a feeler gauge. D. No feeler gauge is required. Answer B is correct. Clean the pistons in a cold tank and then clean the grooves with a ring groove cleaner before measuring. 3. A cylinder power balance test is being performed on a vehicle with sequential fuel injection. The number five cylinder's rpm drop is less than all of the others. Technician A says this could be the result of a restriction in the fuel injector. Technician B says this could be caused by leaking secondary insulation. Who is correct? A. Technician A B. Technician B C. Both A and B D. Neither A or B Answer C is correct. Both restricted fuel injectors and leaking secondary wires will reduce the cylinder's contribution. Anything that would have an affect on the cylinder's power. It could be mechanical like a faulty valve, possibly the ignition, or the fuel mixture affecting this cylinder's power output. 4. A turbocharger wastegate is sticking. Technician A says a stuck open wastegate will result in overboost. Technician B says a stuck closed wastegate will result in an underboost condition. Who is correct? Neither technician is correct. 5. Technician A says a supercharger uses an intercooler to keep the engine's oil cool. Technician B says intercoolers are used on turbochargers to keep the oil cool. Who is correct? Neither technician is correct. 6. A wet compression test is being performed on a four cylinder engine. The number two cylinder's compression is below specifications and remains the same after injecting oil. This result indicates: A. Worn piston rings. B. A faulty valve. C. A hole in the piston. D. Excessive carbon buildup on the piston's dome. Answer A is wrong. If compression increases after injecting oil into the chamber, the piston rings are worn. This is because the oil fills the gap caused by the worn rings increasing the cylinder's compression. Answer B is correct. If there is no change in compression after adding oil, the cylinder has a faulty head gasket or valve. 7. A vehicle has blue colored exhaust. Technician A says this may be caused by weak piston rings. Technician B says this may be caused by a leaking fuel injector. Who is correct? A. Technician A B. Technician B C. Both A and B D. Neither A or B Answer A is correct. Oil is burning in the combustion chamber causing blue colored exhaust. 8. Technician A says to remove the ridge on the engine block before removing the pistons. Technician B says a block's ridge will damage the new piston rings during installation. Who is correct? A. Technician A B. Technician B C. Both A and B D. Neither A or B Answer C is correct. Remove the damaging ridge with a ridge reamer before removing pistons. This also prevents damage to the new piston rings when it comes time to reinstall the pistons. 9. A vehicle briefly blows blue/gray smoke from the tailpipe when it's first started in the morning. The MOST likely cause of this condition is a: A. Worn piston ring. B. Lean fuel condition. C. Leaking fuel injector. D. Leaking valve seal. Answer A is wrong. Worn piston rings would result in blue/gray smoke at all times, not just in the mornings. Answer B is wrong. Both a rich and a lean fuel condition will result in excessive HC's in the emissions. Answer C is wrong. A rich fuel condition will result in black smoke emitting from the tailpipe. Answer D is correct. A leaking valve seal will cause oil to leak into the cylinder's chamber over time, usually overnight. 10. During a cylinder leakage test air bubbles appear in the neck of the radiator. Technician A says a faulty intake valve will cause this condition. Technician B says a crack in the engine block will cause this condition. Who is correct? A. Technician A B. Technician B C. Both A and B D. Neither A or Answer A is wrong. A leaking intake valve will result in a hissing sound from the throttle body. It can be heard by removing the air tube and opening the throttle plate. This is because the intake valve is leaking air into the intake manifold. Answer B is correct. A crack in the blocks deck area or cylinder head allows compression to leak into the coolant jacket. This results in air bubbles appearing in the radiator neck. 11. After diagnosing and replacing the cooling system's water pump, the vehicle's engine continues to overheat. Which of these is the MOST likely cause. A. An air pocket in the system. B. Leaking head gasket. C. Faulty replacement water pump. D. The radiator. Answer A is correct. Air pockets occur after draining the engine's coolant. Some vehicle's are more prone to this problem than others. Answer B is wrong. A leaking head gasket would result in gases escaping the seal and fluids such as coolant leaking in. The vehicle would likely emit white smoke from its tailpipe as coolant burns in the combustion chamber. Answer C is wrong. A faulty replacement water pump is not the most likely answer. Answer D is wrong. The radiator is not the most likely answer. Answer A is correct. 12. Two technicians are discussing engine sealants and form in place gaskets. Technician A says sealants such as RTV are aerobic. Technician B says some sensors may be damaged if an unapproved sealant is used. Who is correct? A. Technician A B. Technician B C. Both A and B D. Neither A or B Answer A is wrong. Both technicians are correct. RTV (Room Temperature Vulcanizing) is an aerobic sealant meaning that it cures in the presence of air. Answer B is wrong. Both technicians are correct. Keep RTV away from sensors Answer C is correct. Anaerobic sealers are usually used on smooth, machined components. They dry in the absence of air. Answer D is wrong. Both technicians are correct. 13. An engine has a noise that goes away as the engine warms and reaches operating temperature. Which of these is the MOST likely cause. A. Loose main bolt. B. Loose connecting rod bolt. C. Piston to wall clearance. D. Loose intake manifold. Answer A is wrong. A loose main bolt is not likely to go away as the engine reaches operating temperature. Answer B is wrong. A spun connecting rod bearing is not likely to go away as the engine reaches operating temperature. Answer C is correct. As the piston expands, the clearance between it and the cylinder wall decreases, and so does the noise known as piston slap Answer D is wrong. A loose intake manifold will cause low vacuum. 14. An engine suffers from detonation. Technician A this may be caused from a defective EGR valve. Technician B says advanced ignition timing can cause this condition. Who is correct? A. Technician A B. Technician B C. Both A and B D. Neither A or B Answer C is correct. A stuck closed EGR valve will cause ping (detonation) while a stuck open valve will cause an engine to stumble and stall. 15. Technician A says faulty turbocharger bearings will result in a loss of engine oil. Technician B says a dirty turbocharger air filter will result in a loss of engine oil. Who is correct? A. Technician A B. Technician B C. Both A and B D. Neither A or B Answer A is correct. Faulty turbocharger bearings will result in oil seal failure. Answer B is wrong. A dirty turbocharger air filter can result in blade damage. A squeal is heard in the front of a supercharged V6 engine. This squeal gets louder as the engine is accelerated. Which of these is causing this condition? A. Supercharger front roller bearings. B. Faulty serpentine belt tensioner. C. Turbine shaft needle bearings. D. Both A and B Answer A is wrong. Superchargers contain roller and needle bearings. They rotate in excess of 10,000 rpm. Answer B is wrong. They are driven by serpentine belts. Answer C is wrong. A turbine wheel is part of a turbocharger. Answer D is correct. Superchargers are belt driven and contain bearings that will squeal when worn or deprived of lubricant. A vehicle's engine is sluggish and slow to crank. Technician A says to check the starter and its circuit first. Technician B says to check the voltage, capacity, and condition of the battery. Who is correct? A. Technician A B. Technician B C. Both A and B D. Neither A or B Answer A is wrong. The battery's a great place to start. Check its voltage, capacity, and condition. Answer B is correct. Always inspect and test the battery and its connections first Answer C is wrong. After the battery, inspect and test on the starter circuit. A vehicle's battery is good and passes all testing, but continues to die overnight. It's being tested for parasitic battery drain. Technician A says to set the meter to measure voltage and connect the probes in series between the positive terminal and the battery post. Technician B says to set the meter to measure amperage and connect the probes in series between the negative battery terminal and the negative battery post. Who is correct? A. Technician A B. Technician B C. Both A and B D. Neither A or B Answer A is wrong. In order to diagnose parasitic battery drain measure the current draining from the battery while the vehicle is at rest. When measuring current set the multimeter for amperage. Answer B is correct. Technician B is correct. Set the meter to measure amperage and connect the probes in series between the negative battery terminal and the negative battery post