ASE A8 Engine Performance Study Questions with Correct Answer

Proper Engine Performance -Emission levels that are allowances and good fuel economy, that all depend on a quality. -Well timed spark, fuel, air, and compression are factors that determine the quality. -No matter how complicated the engine and its controls become, it will always depend on those 4 components. Factors to consider when diagnosing engine performance problems -diagnosis should be addressed in a logical manner, using the process of elimination -question the driver on the symptoms -when they occur -how long they have been occurring -what does the customer have to do to experience the problem -is there a temperature , running time, time spent without running, speed, or road condition factor involved. Factors to keep in mind -check under hood for obvious problems -check the drive belt for looseness, cracks, fraying, or glazing -check the battery cables and all electrical wires. (Quite often a problem in a computerized engine control system is caused by broken/abraded wires or corroded connectors rather than a component failing. -check the integrity and routing of all vacuum lines. Some first steps to consider -check service history for similar issues/complaints -check for tsb's -starting research at this point is ideal because it will minimize time spent trying to diagnose. -check for recalls and service campaigns. Tests to be performed to check mechanical health of the engine -vacuum test -compression test -cylinder leakage test -cylinder balance test Engine noises -crankshaft noises (main bearings, connecting rod bearings, pistons, wrist pin, crankshaft end play). -valvetrain noises (bearing noise, rocker arms, rocker shafts, rocker ball and seat, push rods, tappets, camshaft, timing gears and chain). -other noises ( loose or broken brackets, oil pump failure, spark knock). General cause of noises -too much clearance between parts, or loss of oil pressure. Main Bearing noises - caused by too much clearance due to worn bearings or crankshaft journals or a lack of lubrication. -usually indicated by a deep or dull sounding metallic knocking (when rpms increase the knocking frequency will also increase.) -the noise is usually most obvious after start up/under heavy load or during acceleration. -the engine may also exhibit low oil pressure. Connecting rod noises -caused by excessive bearing clearance, lack of lubrication. -the sound is much less intense than the main bearing noise -this noise usually sounds like a light metallic rapping that is most noticeable under engine running during a light load at relatively low speeds. -when you eliminate the ignition or injection from the cylinder, the rod knock should diminish.