ASE A1 Engine Repair Certification Practice Test
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. Who is correct???
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
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 speci-
fied 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
1
,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:
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 con-
clusive.
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 con-
tribute too little power
While discussing basic diagnostic procedures,
2
,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
-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,
3
, 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 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, - ANSWER 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:
4
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. Who is correct???
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
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 speci-
fied 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
1
,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:
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 con-
clusive.
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 con-
tribute too little power
While discussing basic diagnostic procedures,
2
,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
-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,
3
, 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 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, - ANSWER 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:
4
