Deck 7: Valve Train and Variable Valve Timing Diagnosis

Question 1

The operation of the valvetrain determines ________.

A) the timing of when the valves are opened and closed
B) the distance the valves open
C) the duration of the opening and closing of the valves
D) All of the above

Answer 1

D

Question 2

To reduce oxides of nitrogen (NO_x) exhaust emissions, which camshaft is varied?

A) The exhaust camshaft is advanced and the intake camshaft is advanced
B) Exhaust camshaft only
C) Intake camshaft only
D) Both the intake and exhaust camshaft

Answer 2

B

Question 3

What is different about the Atkinson cycle valve timing?

A) The engine with an Atkinson cycle uses a lower compression ratio
B) Uses a shorter exhaust valve timing
C) Increases low speed torque output of the engine
D) Improves engine efficiency

Answer 3

D

Question 4

All of the following could cause noise in the valvetrain EXCEPT ________.

A) oil level too high
B) oil level too low
C) an original equipment oil filter
D) worn cam lobe

Question 5

What sensors are used by the PCM to determine the best position of the camshafts for maximum power and lowest possible exhaust emissions?

A) Camshaft position (CMP) sensor
B) Engine speed (RPM)
C) Crankshaft position (CKP) sensor
D) All of the above

Question 6

How is the camshaft actuator controlled?

A) Vacuum controlled valve
B) On only when conditions are right
C) Pulse width modulated (PWM) signal
D) Spring loaded to the correct position based on engine speed

Question 7

If the engine oil is not changed regularly, what is the most likely fault that can occur to an engine equipped with variable valve timing (VVT)?

A) A no-start condition because the camshaft cannot rotate
B) Low oil pressure diagnostic trouble code (DTC)
C) The filter screens on the actuator control valve become clogged
D) Any of the above

Question 8

How quickly can the rocker arms be switched from the low-speed camshaft profile to the high-speed camshaft profile on a Honda equipped with a VTEC system?

A) 500 milliseconds
B) 50 milliseconds
C) 250 milliseconds
D) 100 milliseconds

Question 9

What sequence of events occurs to trap some exhaust in the cylinder during a cylinder deactivation event?

A) The intake valve is disabled and the fuel injection is stopped
B) After a normal combustion event has occurred, the exhaust valve is closed
C) The sequence is repeated according to the firing order of the engine
D) All of the above

Question 10

If the incorrect grade of engine oil is used in and engine equipped with a variable displacement engine, what diagnostic trouble code (DTC) could be set?

A) P0521
B) P0420
C) P0300
D) P0011

Question 11

Variable valve timing can be found on which type of engine?

A) DOHC
B) Cam-in-block
C) SOHC
D) All of the above

Question 12

To increase engine performance, which camshaft is varied?

A) The exhaust camshaft is advanced and the intake camshaft is advanced
B) Exhaust camshaft only
C) Intake camshaft only
D) Both the intake and exhaust camshaft

Question 13

Which diagnostic trouble code (DTC) may be set if there is a problem with the bank 1 intake cam position?

A) P0011 or P0012
B) P0300
C) P0420
D) P0021 or P0022

Question 14

Variable valve timing is used to ________.

A) increase engine performance
B) reduce exhaust emissions
C) reduce engine wear
D) Both A and B

Question 15

Technician A says that active fuel management is only used on large V8s. Technician B says that active fuel management increases fuel economy. Which technician is correct?

A) Technician A only
B) Technician B only
C) Both Technicians A and B
D) Neither Technician A nor B

Question 16

Active fuel management on GM vehicles was initially called ________.

A) variable cylinder operation
B) fuel economy enhancement
C) Displacement on Demand
D) None of these

Question 17

The use of variable valve timing allows the elimination of the ________ on some engines.

A) PCV control valve
B) exhaust valves
C) TAC snorkel valve
D) EGR valve

Question 18

On some engines, what holds the cam in position during cranking?

A) A locking pin
B) Oil pressure
C) Oil screens
D) A magnet

Question 19

On engines that have variable cam timing on the intake cam only, the cam is advanced at lower speeds. This causes the intake valve to close ________ to improve low RPM torque.

A) later
B) earlier
C) higher
D) None of these

Question 20

Most variable camshaft systems use ________ to control camshaft position.

A) atmospheric pressure
B) oil pressure
C) vacuum
D) air pressure

Question 21

A VTEC engine changes cam lift and timing by using oil pressure and a locking pin in the ________.

A) Cam sprocket
B) Rocker arms
C) Timing belt drive
D) Push rods

Question 22

What is the first step in diagnosing variable camshaft timing systems?

A) Open the hood and do a visual inspection
B) Verify the customer concern
C) Check for DTCs
D) None of these

Question 23

A variable displacement engine changes effective displacement by ________.

A) deactivating cylinders
B) blocking the intake manifold
C) changing manifold length
D) changing piston stroke

Question 24

On many variable displacement engines, the cylinder deactivation is done by use of a(an) ________.

A) Cam shifting
B) Two stage hydraulic lifter
C) Spark retard
D) None of these

Question 25

A stored emission-related fault code could disable the cylinder deactivation system.