Four Stroke Combustion Cycle and Engine Vacuum Quiz

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What is a good indicator of a piston ring sealing problem during cranking compression analysis?

High pressure on the first "puff" and consistent pressure build

Low pressure on the first "puff" and inconsistent pressure build (correct)

Low pressure on the first "puff" that gradually increases

Steady rise in pressure with each "puff"

What can cause low compression that doesn't improve with a wet test according to the text?

Leaking valves

A hole in the piston

A head gasket leak

All of the above (correct)

When should you suspect a leaking head gasket according to the text?

High compression in two adjacent cylinders

Steady compression in two adjacent cylinders

Low compression that improves with the wet test

Low compression in two adjacent cylinders (correct)

What is the purpose of performing a Cylinder Leakage test as mentioned in the text?

To isolate the cause of low compression Signup and view all the answers

Why is it important for the engine to be warm when conducting a Cylinder Leakage test?

To ensure accurate results from the test Signup and view all the answers

During which stroke does a low pressure get created in the engine?

Intake stroke Signup and view all the answers

What can a poor cylinder seal result in?

Reduced combustion pressure Signup and view all the answers

What is the effect of abnormal combustion on engine performance?

Reduced power output Signup and view all the answers

What should be done to avoid personal injury or component damage when conducting cranking compression testing?

Disable Fuel and Ignition systems Signup and view all the answers

What happens to the manifold vacuum test results when using newer intake manifold designs?

Results are unpredictable Signup and view all the answers

What is the purpose of cranking the engine through one compression stroke 'puff' when performing cranking compression testing?

To record PSI for comparison Signup and view all the answers

What does the Intake Air Temperature (IAT) Sensor primarily help to adjust?

Air-fuel ratio Signup and view all the answers

How does the Manifold Absolute Pressure (MAP) Sensor respond to changes in applied vacuum?

Sensor voltage increases Signup and view all the answers

What is the main purpose of the Ignition Reference Signals for the PCM?

Control spark timing Signup and view all the answers

How does the Vehicle Speed Sensor (VSS) generate a signal that increases with vehicle speed?

Current increases Signup and view all the answers

What does the Knock Sensor System signal to the PCM lead to?

Ignition timing adjustment Signup and view all the answers

What is the primary function of the Fuel Tank Pressure Sensor?

Detect leaks in the emissions system Signup and view all the answers

What does the PCV system do?

Reduces buildup of moisture and sludge in the crankcase Signup and view all the answers

What is the main purpose of a catalytic converter?

Converting CO, HC, and NOx into water, carbon dioxide, and nitrogen Signup and view all the answers

Which component is responsible for providing additional oxygen to the exhaust stream?

Secondary Air Injection System Signup and view all the answers

What is the purpose of ORVR (On-Board Refueling Vapor Recovery)?

Prevent fuel vapors from escaping during refueling Signup and view all the answers

What kind of signal does the automotive computer understand?

Digital signal with only two voltage levels: on and off Signup and view all the answers

In Closed Loop operation, what air/fuel ratio is typically maintained based on O2 feedback?

14.7:1 Signup and view all the answers

What is the primary function of a PROM (Programmable Read Only Memory)?

Contains low-level instructions for managing engine tasks Signup and view all the answers

What does EEPROM stand for in the context of automotive computers?

'Electrically Erasable Programmable Read Only Memory' Signup and view all the answers

'Baud rate' refers to which aspect of serial data communication?

'The number of data bits transmitted per second' Signup and view all the answers

'Clear Flood' mode is activated by pressing the accelerator pedal to the floor to achieve what target throttle position?

'80% TP' Signup and view all the answers