ASE A1 (Engine Repair) Practice Test – Cumulative Questions and Answers

ASE A1 (Engine Repair) Practice Test – Cumulative Questions and Answers an engine miss is being diagnosed using a cylinder leakage test. Technician A says that any cylinder with over 20% leakage has excessive leakage. Tech B says that air leaking from the tailpipe indicates a cracked cylinder. A only, B only, A & B, Neither . - Answer-A only: If cylinder leakage exceeds 20%, check for air escaping the tailpipe, the PCV valve opening in the rocker arm cover, and the top of the throttle body or carburetor. Air leaking from the tailpipe usually indicates an exhaust valve leak EMILLECT 2024/2025 ACADEMIC YEAR ©2024 EMILLECT. ALL RIGHTS RESERVED FIRST PUBLISH OCTOBER, 2024 Page 2/106 during a compression test, a cylinder has 40% of the specified compression reading. When the tech performs a wet test, the compression reading on this cylinder has 75% of the specified reading. The cause of the low compression reading could be worn piston rings, a burned exhaust valve, a bent intake valve, a worn camshaft lobe, - Answer-worn piston rings if compression increases during a wet test, this indicates worn piston rings. Compression would not increase if an exhaust valve is burned, intake valve is bent, or camshaft lobe is worn. the customer complains that the engine cranks but does not start; the first thing to check should be valve train operation, battery voltage, compression, engine vacuum, - Answer-valve train operation: EMILLECT 2024/2025 ACADEMIC YEAR ©2024 EMILLECT. ALL RIGHTS RESERVED FIRST PUBLISH OCTOBER, 2024 Page 3/106 if the engine cranks properly, the battery is not the problem. Compression would not be the FIRST test, and because engine vacuum is low during a crank, a vacuum test would not be conclusive. during a cylinder balance test on an engine with fuel injection, one cylinder provides very little rpm drop. Tech A says the ignition system may be misfiring on that cylinder. Tech B says the engine may have an intake manifold vacuum leak. A only, B only, A & B, Neither , - Answer-Both A&B Both a misfiring ignition system and an intake manifold leak could cause a cylinder to contribute too little power while discussing basic diagnostic procedures, EMILLECT 2024/2025 ACADEMIC YEAR ©2024 EMILLECT. ALL RIGHTS RESERVED FIRST PUBLISH OCTOBER, 2024 Page 4/106 Tech A says the most complicated diagnostic tests should be performed first. Tech B says that you should first question the customer to obtain as much info as possible about the problem A, B , A & B, Neither, - Answer-B Always attempt the more simple diagnosis first with the engine idling, a vacuum gauge connected to the intake manifold fluctuates (from 15 to 20). These fluctuations may be caused by late ignition timing, intake manifold vacuum leaks, a restricted exhaust system, sticky valve stems and guides, - Answer-sticky valve stems and guides EMILLECT 2024/2025 ACADEMIC YEAR ©2024 EMILLECT. ALL RIGHTS RESERVED FIRST PUBLISH OCTOBER, 2024 Page 5/106 -late ignition timing would result in a low, steady reading -intake manifold leaks would cause a very low, steady reading -a restricted exhaust system would cause vacuum to slowly decrease after the engine was accelerated and held steady oil is leaking from the crankshaft rear main bearing seal on an engine. Tech A says the oil seal could be faulty. Tech B says the PCV system may not be functioning. A, B, A & B, Neither, - Answer-A&B A high-pitched squealing noise is heard during hard acceleration. This may be the cause of: intake manifold leak, the choke stuck closed fuel system leak small leak in exhaust manifold - Answer-small leak in exh