ASE A1 CORE EXAMS SET 2025/2026 QUESTIONS WITH
SOLUTIONS MARKED A+
✔✔to check for plugged oil drain passages - ✔✔-remove the oil filter (or anything else
fitted to the valve cover) and start the engine and check to see if oil inside the cover
rises and reaches the top
✔✔an engine burning coolant will emit - ✔✔gray or white exhaust
✔✔coolant leaking into oil will cause - ✔✔oil sludge
✔✔electronic carburetor or fuel injection cars with coolant passing through the exhaust
system will - ✔✔poison the oxygen sensor
✔✔if all cylinders are firing properly the exhaust should consist of - ✔✔steady pulses
✔✔a puffing noise at regular intervals indicates a - ✔✔cylinder misfire caused by a
compression, ignition, or fuel system defect.
✔✔puffing noises at irregular (erratic) intervals are usually caused by - ✔✔ignition or
fuel system defects
✔✔a high-pitched squealing noise during hard acceleration may be caused by a -
✔✔small leak in the exhaust system, particularly in the manifolds or tailpipe
✔✔a leak in the exhaust system (contrary to hard acceleration) may also cause - ✔✔a
ticking noise at idle
✔✔a high-pitched whistle at idle or low engine speeds usually is a result of - ✔✔vacuum
leaks.
✔✔vacuum leaks usually occur in - ✔✔intake manifold gaskets or in the vacuum hoses
themselves
✔✔a vacuum leak whistle gradually - ✔✔decreases when the engine is accelerated and
the intake vacuum decreases
✔✔a strong sulfur, or rotten egg, smell coming from the exhaust of a car with a cat may
indicate - ✔✔a rich air/fuel ratio
✔✔a vacuum test can be used to help pinpoint - ✔✔the cause of an engine problem
✔✔the vacuum gauge (for a vacuum test) should be connected directly - ✔✔to the
intake manifold
, ✔✔during a vacuum test, an engine performing properly should read - ✔✔between 17
and 22 in. Hg and steady with engine idle
✔✔a slightly low but steady vacuum reading indicates - ✔✔late ignition timing
✔✔a very low but steady vacuum reading indicates - ✔✔significant leak in intake
manifold
✔✔when the vacuum reading gauge pointer drifts back and forth between 11 and 16 in
Hg (approximately) - ✔✔- on a carb engine, the idle mixture screws should be adjusted
_ on a f.i. engine, injectors require cleaning or replacing
✔✔a vacuum reading fluctuation between 12 and 18 in Hg indicates - ✔✔burned or
leaking valves
✔✔a vacuum reading fluctuation between 10 and 25 in Hg indicates - ✔✔weak valve
springs
✔✔a vacuum reading fluctuation between 7 and 20 in Hg indicates - ✔✔a leaking head
gasket
✔✔a vacuum reading fluctuation between 14 and 18 in Hg indicates - ✔✔the valves are
sticking
✔✔if, when the engine is accelerated and held steady at a higher speed, the vacuum
gauge pointer gradually rises - ✔✔the cat or other exhaust system components are
restricted
✔✔if all cylinders in an engine are functioning properly, each one _____;
therefore, disabling, or "knocking out," the ignition spark in the cylinders, one at a time,
should cause - ✔✔contributes the same amount of power;
engine speed to drop the same amount for each cylinder.
✔✔if engine speed drops very little when a particular cylinder is disable - ✔✔the
cylinder is not contributing the same amount of power as the others
✔✔ignition system components can be checked visually and, if no problem is obvious,
with an - ✔✔engine analyzer or oscilloscope
SOLUTIONS MARKED A+
✔✔to check for plugged oil drain passages - ✔✔-remove the oil filter (or anything else
fitted to the valve cover) and start the engine and check to see if oil inside the cover
rises and reaches the top
✔✔an engine burning coolant will emit - ✔✔gray or white exhaust
✔✔coolant leaking into oil will cause - ✔✔oil sludge
✔✔electronic carburetor or fuel injection cars with coolant passing through the exhaust
system will - ✔✔poison the oxygen sensor
✔✔if all cylinders are firing properly the exhaust should consist of - ✔✔steady pulses
✔✔a puffing noise at regular intervals indicates a - ✔✔cylinder misfire caused by a
compression, ignition, or fuel system defect.
✔✔puffing noises at irregular (erratic) intervals are usually caused by - ✔✔ignition or
fuel system defects
✔✔a high-pitched squealing noise during hard acceleration may be caused by a -
✔✔small leak in the exhaust system, particularly in the manifolds or tailpipe
✔✔a leak in the exhaust system (contrary to hard acceleration) may also cause - ✔✔a
ticking noise at idle
✔✔a high-pitched whistle at idle or low engine speeds usually is a result of - ✔✔vacuum
leaks.
✔✔vacuum leaks usually occur in - ✔✔intake manifold gaskets or in the vacuum hoses
themselves
✔✔a vacuum leak whistle gradually - ✔✔decreases when the engine is accelerated and
the intake vacuum decreases
✔✔a strong sulfur, or rotten egg, smell coming from the exhaust of a car with a cat may
indicate - ✔✔a rich air/fuel ratio
✔✔a vacuum test can be used to help pinpoint - ✔✔the cause of an engine problem
✔✔the vacuum gauge (for a vacuum test) should be connected directly - ✔✔to the
intake manifold
, ✔✔during a vacuum test, an engine performing properly should read - ✔✔between 17
and 22 in. Hg and steady with engine idle
✔✔a slightly low but steady vacuum reading indicates - ✔✔late ignition timing
✔✔a very low but steady vacuum reading indicates - ✔✔significant leak in intake
manifold
✔✔when the vacuum reading gauge pointer drifts back and forth between 11 and 16 in
Hg (approximately) - ✔✔- on a carb engine, the idle mixture screws should be adjusted
_ on a f.i. engine, injectors require cleaning or replacing
✔✔a vacuum reading fluctuation between 12 and 18 in Hg indicates - ✔✔burned or
leaking valves
✔✔a vacuum reading fluctuation between 10 and 25 in Hg indicates - ✔✔weak valve
springs
✔✔a vacuum reading fluctuation between 7 and 20 in Hg indicates - ✔✔a leaking head
gasket
✔✔a vacuum reading fluctuation between 14 and 18 in Hg indicates - ✔✔the valves are
sticking
✔✔if, when the engine is accelerated and held steady at a higher speed, the vacuum
gauge pointer gradually rises - ✔✔the cat or other exhaust system components are
restricted
✔✔if all cylinders in an engine are functioning properly, each one _____;
therefore, disabling, or "knocking out," the ignition spark in the cylinders, one at a time,
should cause - ✔✔contributes the same amount of power;
engine speed to drop the same amount for each cylinder.
✔✔if engine speed drops very little when a particular cylinder is disable - ✔✔the
cylinder is not contributing the same amount of power as the others
✔✔ignition system components can be checked visually and, if no problem is obvious,
with an - ✔✔engine analyzer or oscilloscope
