ASE A1 (Engine Repair) Practice Test –
Cumulative Exam Questions with
Solutions
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 . - -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
-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, - -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, - -valve train operation:
,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 , - -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,
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, - -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, - -sticky valve stems and guides
-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, - -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 - -small leak in exhaust manifold
-intake manifold leak causes a high-pitched whistle at idle and low speeds
-carb choke stuck closed will not cause a high-pitched whistle
-fuel system leak normally would not cause a noise
-a heavy thumping noise occurs with the engine idling, but the oil pressure
is normal. this may be caused by:
worn pistons and cylinders,
loose flywheel bolts,
worm main bearings,
loose camshaft bearings, - -loose flywheel bolts
-worn pistons and cylinders would cause a thumping noise during
acceleration
-worn main bearings cause a thump when the engine is started
-loose camshaft bearings would cause a growling noise at all times
-after a vehicle is parked overnight and then started in the morning, the
engine has a lifter noise that disappears after running for a short time. this
may be caused by:
low oil pressure,
low oil level,
worn lifter bottom,
excessive lifter leak-down, - -excessive lifter leak-down
low oil pressure would result in a continuous noise
low oil level would result in a continuous noise
worn lifter bottom would result in a continuous noise
-when using a compression tester, the readings on the cylinders are all
even, but lower than spec. this could indicate:
, blown head gasket,
carbon buildup,
cracked head,
worn rings and cylinders, - -worn rings and cylinders
-a low reading on two adjacent cylinders may indicate a blown head gasket
-carbon buildup would cause a high reading
-a low reading on two adjacent cylinders may indicate a cracked head
-a cylinder balance test is being performed on an engine to determine which
cylinder is causing a miss.
Tech A says that when the faulty cylinder is disabled, engine rpm will drop
more than for the other cylinders.
Tech B says disabling the faulty cylinder will cause the engine to stall
A,
B,
Both,
Neither, - -Neither
the faulty cylinder will not cause the engine to stall, neither will it cause the
engine to drop in RPM since it is faulty.
-an engine is idling at 750 rpm. the pointer on the vacuum gauge is floating
between 11 and 16 in Hg. The most likely cause is
retarded timing,
advanced timing,
stuch EGR valve,
too lean idle mixture, - -too lean idle mixture
all others would not result in gauge fluctuation
-the first step a Tech should take for diagnosis is:
think of possible causes of the problem,
question the customer,
road test the vehicle,
listen to the customer, - -listen to the customer
-the customer says that the engine requires excessive cranking to start. the
LEAST likely cause of this problem would be:
cracked cylinder block,
jumped timing belt,
Cumulative Exam Questions with
Solutions
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 . - -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
-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, - -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, - -valve train operation:
,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 , - -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,
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, - -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, - -sticky valve stems and guides
-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, - -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 - -small leak in exhaust manifold
-intake manifold leak causes a high-pitched whistle at idle and low speeds
-carb choke stuck closed will not cause a high-pitched whistle
-fuel system leak normally would not cause a noise
-a heavy thumping noise occurs with the engine idling, but the oil pressure
is normal. this may be caused by:
worn pistons and cylinders,
loose flywheel bolts,
worm main bearings,
loose camshaft bearings, - -loose flywheel bolts
-worn pistons and cylinders would cause a thumping noise during
acceleration
-worn main bearings cause a thump when the engine is started
-loose camshaft bearings would cause a growling noise at all times
-after a vehicle is parked overnight and then started in the morning, the
engine has a lifter noise that disappears after running for a short time. this
may be caused by:
low oil pressure,
low oil level,
worn lifter bottom,
excessive lifter leak-down, - -excessive lifter leak-down
low oil pressure would result in a continuous noise
low oil level would result in a continuous noise
worn lifter bottom would result in a continuous noise
-when using a compression tester, the readings on the cylinders are all
even, but lower than spec. this could indicate:
, blown head gasket,
carbon buildup,
cracked head,
worn rings and cylinders, - -worn rings and cylinders
-a low reading on two adjacent cylinders may indicate a blown head gasket
-carbon buildup would cause a high reading
-a low reading on two adjacent cylinders may indicate a cracked head
-a cylinder balance test is being performed on an engine to determine which
cylinder is causing a miss.
Tech A says that when the faulty cylinder is disabled, engine rpm will drop
more than for the other cylinders.
Tech B says disabling the faulty cylinder will cause the engine to stall
A,
B,
Both,
Neither, - -Neither
the faulty cylinder will not cause the engine to stall, neither will it cause the
engine to drop in RPM since it is faulty.
-an engine is idling at 750 rpm. the pointer on the vacuum gauge is floating
between 11 and 16 in Hg. The most likely cause is
retarded timing,
advanced timing,
stuch EGR valve,
too lean idle mixture, - -too lean idle mixture
all others would not result in gauge fluctuation
-the first step a Tech should take for diagnosis is:
think of possible causes of the problem,
question the customer,
road test the vehicle,
listen to the customer, - -listen to the customer
-the customer says that the engine requires excessive cranking to start. the
LEAST likely cause of this problem would be:
cracked cylinder block,
jumped timing belt,
