ASE A1 (ENGINE REPAIR) TEST - CUMULATIVE UPDATED
ACTUAL QUESTIONS AND CORRECT ANSWERS
Question:
1. 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
Question:
2. 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.
Question:
3. 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 conclusive.
Question:
4. 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
,Question:
5. 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,
Answer:
B
Always attempt the more simple diagnosis first
Question:
6. 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
Question:
7. 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
Question:
8. 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
Question:
9. 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
,Question:
10. 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,
Answer:
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
Question:
11. 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,
Answer:
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
Question:
12. 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,
Answer:
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.
Question:
13. 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,
Answer:
too lean idle mixture
all others would not result in gauge fluctuation
Question:
14. 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,
Answer:
listen to the customer
Question:
15. 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, faulty fuel pump, stuck-open EGR valve,
, Answer:
cracked cylinder block
Question:
16. which of the following is LEAST likely to cause engine noise?
loose pistons, worn cylinders, worn main bearings, loose camshaft bearings,
Answer:
loose cam bearings
-loose pistons may cause a rapping noise while accel
-worn cylinders may cause a rapping noise while accel
-worn main bearings may cause a thumping noise when starting
Question:
17. the least likely first step in a diagnosis would be to:
question the customer for more info, be sure that the customer complaint is eliminated start with the most
difficult test road test the vehicle
Answer:
start with the most difficult test
Question:
18. a cylinder balance test on a carbureted engine has revealed one cylinder is contributing less power than
the others. The LEAST likely cause of this is:
faulty ignition system burned exhaust valve faulty carburetor leaking intake manifold
Answer:
faulty carburetor
-faulty ignition system, burned exhaust valve, and leaking intake manifold are likely to cause one cylinder
to provide less power than others. The carburetor would not cause one single cylinder to contribute less
power.
Question:
19. an excessive sulfur smell in the exhaust with a cat can be an indication of:
lean fuel mixture coolant leaking into combustion chamber rich fuel mixture vacuum leak
Answer:
rich fuel mixture
-lean fuel mixture would not cause a sulfur smell
-coolant leaking into the chamber would cause a gray exhaust color
-a vacuum leak would cause a rough idle that would decrease as engine speed increases
Question:
20. a low, steady vacuum gauge reading from 11 to 15 indicates:
burned or leaking valves late ignition timing weak valve springs leaking head gasket
Answer:
late ignition timing
-burned or leaking valves cause a fluctuation between 12 and 18
-weak valve springs cause a fluctuation between 10 and 25
-leaking head gasket would cause a fluctuation between 7 and 20
ACTUAL QUESTIONS AND CORRECT ANSWERS
Question:
1. 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
Question:
2. 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.
Question:
3. 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 conclusive.
Question:
4. 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
,Question:
5. 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,
Answer:
B
Always attempt the more simple diagnosis first
Question:
6. 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
Question:
7. 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
Question:
8. 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
Question:
9. 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
,Question:
10. 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,
Answer:
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
Question:
11. 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,
Answer:
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
Question:
12. 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,
Answer:
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.
Question:
13. 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,
Answer:
too lean idle mixture
all others would not result in gauge fluctuation
Question:
14. 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,
Answer:
listen to the customer
Question:
15. 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, faulty fuel pump, stuck-open EGR valve,
, Answer:
cracked cylinder block
Question:
16. which of the following is LEAST likely to cause engine noise?
loose pistons, worn cylinders, worn main bearings, loose camshaft bearings,
Answer:
loose cam bearings
-loose pistons may cause a rapping noise while accel
-worn cylinders may cause a rapping noise while accel
-worn main bearings may cause a thumping noise when starting
Question:
17. the least likely first step in a diagnosis would be to:
question the customer for more info, be sure that the customer complaint is eliminated start with the most
difficult test road test the vehicle
Answer:
start with the most difficult test
Question:
18. a cylinder balance test on a carbureted engine has revealed one cylinder is contributing less power than
the others. The LEAST likely cause of this is:
faulty ignition system burned exhaust valve faulty carburetor leaking intake manifold
Answer:
faulty carburetor
-faulty ignition system, burned exhaust valve, and leaking intake manifold are likely to cause one cylinder
to provide less power than others. The carburetor would not cause one single cylinder to contribute less
power.
Question:
19. an excessive sulfur smell in the exhaust with a cat can be an indication of:
lean fuel mixture coolant leaking into combustion chamber rich fuel mixture vacuum leak
Answer:
rich fuel mixture
-lean fuel mixture would not cause a sulfur smell
-coolant leaking into the chamber would cause a gray exhaust color
-a vacuum leak would cause a rough idle that would decrease as engine speed increases
Question:
20. a low, steady vacuum gauge reading from 11 to 15 indicates:
burned or leaking valves late ignition timing weak valve springs leaking head gasket
Answer:
late ignition timing
-burned or leaking valves cause a fluctuation between 12 and 18
-weak valve springs cause a fluctuation between 10 and 25
-leaking head gasket would cause a fluctuation between 7 and 20
