27 Questions
What is a good indicator of a piston ring sealing problem during cranking compression analysis?
Low pressure on the first "puff" and inconsistent pressure build
What can cause low compression that doesn't improve with a wet test according to the text?
All of the above
When should you suspect a leaking head gasket according to the text?
Low compression in two adjacent cylinders
What is the purpose of performing a Cylinder Leakage test as mentioned in the text?
To isolate the cause of low compression
Why is it important for the engine to be warm when conducting a Cylinder Leakage test?
To ensure accurate results from the test
During which stroke does a low pressure get created in the engine?
Intake stroke
What can a poor cylinder seal result in?
Reduced combustion pressure
What is the effect of abnormal combustion on engine performance?
Reduced power output
What should be done to avoid personal injury or component damage when conducting cranking compression testing?
Disable Fuel and Ignition systems
What happens to the manifold vacuum test results when using newer intake manifold designs?
Results are unpredictable
What is the purpose of cranking the engine through one compression stroke 'puff' when performing cranking compression testing?
To record PSI for comparison
What does the Intake Air Temperature (IAT) Sensor primarily help to adjust?
Air-fuel ratio
How does the Manifold Absolute Pressure (MAP) Sensor respond to changes in applied vacuum?
Sensor voltage increases
What is the main purpose of the Ignition Reference Signals for the PCM?
Control spark timing
How does the Vehicle Speed Sensor (VSS) generate a signal that increases with vehicle speed?
Current increases
What does the Knock Sensor System signal to the PCM lead to?
Ignition timing adjustment
What is the primary function of the Fuel Tank Pressure Sensor?
Detect leaks in the emissions system
What does the PCV system do?
Reduces buildup of moisture and sludge in the crankcase
What is the main purpose of a catalytic converter?
Converting CO, HC, and NOx into water, carbon dioxide, and nitrogen
Which component is responsible for providing additional oxygen to the exhaust stream?
Secondary Air Injection System
What is the purpose of ORVR (On-Board Refueling Vapor Recovery)?
Prevent fuel vapors from escaping during refueling
What kind of signal does the automotive computer understand?
Digital signal with only two voltage levels: on and off
In Closed Loop operation, what air/fuel ratio is typically maintained based on O2 feedback?
14.7:1
What is the primary function of a PROM (Programmable Read Only Memory)?
Contains low-level instructions for managing engine tasks
What does EEPROM stand for in the context of automotive computers?
'Electrically Erasable Programmable Read Only Memory'
'Baud rate' refers to which aspect of serial data communication?
'The number of data bits transmitted per second'
'Clear Flood' mode is activated by pressing the accelerator pedal to the floor to achieve what target throttle position?
'80% TP'
Test your knowledge on the effects of compression in a four-stroke combustion cycle, abnormal combustion, volumetric efficiency, combustion chamber design, and engine vacuum. Learn about the importance of manifold vacuum tests and their limitations.
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