Chapter 72 Engine Performance

When the oxygen sensor reaches it's operating temperature, around __________, it sends an output voltage to the control unit to signal whether the mixture is richer or leaner than a lambda value of 1.

600° F

A DTC indicates that a vehicle has experienced all of these EXCEPT:

A broken "hard part."

The PCM of an engine is comprised of all of the following parts EXCEPT:

A feedback control section.

Which of these is a device able to electronically communicate with and extract data from the vehicle's one or more on-board computers?

A scan tool

Any of these may be required to diagnose a vehicle when diagnostic trouble codes (DTC's) have NOT been set EXCEPT:

An analog ohmmeter.

High priority faults that require continuous monitoring include all of the following EXCEPT:

An oxygen sensor monitor.

The __________ specifically measures the pressure on the air around us.

BARO

Technician A says sometimes MAF sensors can be cleaned when they have a buildup of dirt and contamination. Technician B says some manufacturers specifically say not to clean their MAF sensors. Who is correct?

Both Tech A and B

Technician A says that a drive-by-wire refers to an engine that utilizes an electronically controlled throttle. Technician B says that an electronically controlled throttle uses a position sensor on the accelerator pedal to calculate the drivers desired throttle position. Who is correct?

Both Tech A and B

Technician A says crankshaft position sensors can be a magnetic pickup-style sensor. Technician B says crankshaft position sensors can be a Hall-effect sensor. Who is correct?

Both Technician A and Technician B

Technician A says that OBD-I systems were typically limited to well under 100 possible faults. Technician B says that OBD-II standardized items such as location and pin assignments for the diagnostic connector. Who is correct?

Both Technician A and Technician B

Technician A says that a relay is a controlled device that receives signals from the PCM. Technician B says that a solenoid is a controlled device that receives signals from the PCM. Who is correct?

Both Technician A and Technician B

Technician A states that simple scan tools from the 1980s could read and erase fault codes. Technician B states that modern scan tools can display sensor data in a graphical format. Who is correct?

Both Technician A and Technician B

Technician A says that the output drivers in the PCM typically send either simple on/off signals or pulse-width-modulated signals to the actuators, depending on the actuator being controlled. Technician B says that in many cases, the software in the PCM's memory can be updated by uploading software updates, called a reflash process. Who is correct?

Both Technicians A and Technician B

Which of the following sensors is used to report the number one piston on the compression stroke?

Camshaft position sensor

In an engine management system, work is done by the actuators, which consist of all of the following EXCEPT:

Capacitors.

Which of the following modes is used by technicians during a cranking sound diagnosis test to fool the engine into cranking without starting?

Clear flood mode

Continuous monitors are run for systems that could:

Contribute to major emissions failures.

Which of the following sensors can the Powertrain Control Module (PCM) use to determine engine speed?

Crankshaft position (CKP) sensor

Which of the following sensors are most involved in the control of ignition timing and injection sequencing?

Crankshaft position sensor

On-board diagnostic (OBD) systems help the service tech do all of following EXCEPT:

Determine exactly where faults exist.

Which of these is the best place to start gathering information and planning a diagnostic pathway based on suspected systems and components?

Diagnostic trouble codes (DTCs) and customer information

If the MIL flashes, it indicates that the:

Driver should stop the vehicle as soon as safely possible.

______ monitors the system for leaks as well as the ability to purge the canister of vapors.

Evaporative system monitor

A fault code that begins with the letter "P" would most likely address a fault in the:

Exhaust system.

Cost and complexity increase with the level of ______ desired in a scan tool.

Features

All of the following statements with respect to freeze-frame data are true EXCEPT:

Freeze-frame data are saved for all DTCs stored in memory.

Which of the following is NOT an example of an electric motor actuator?

Fuel injector

Which of the following is a continuous monitor?

Fuel system monitor

All of the following statements regarding DLC are true EXCEPT:

It's location is also now fairly standardized as being within 2' of the engine.

A(n) _________ sensor directly measures the mass of filtered air entering the engine.

MAF

The __________ measures changes in engine speed and engine load in the intake manifold.

MAP

The barometric pressure (BARO) sensor works in conjunction with the _______.

MAP sensor

Which of the following sensors provides information that is the most critical for proper air-fuel mixture, as well as ignition timing?

MAP sensor

Which part of a powertrain control module retains diagnostic trouble codes (DTCs), freeze-frame data, and learned data?

Memory and storage section

The ________ continuously monitors either crankshaft speed or possibly combustion chamber feedback that indicates misfiring cylinders.

Misfire monitor

Technician A says that any vehicle made after 1976 will use two oxygen sensors. Technician B says that oxygen sensors are located in the intake manifold. Who is correct?

Neither Technician A nor Technician B

Technician A says that in modern vehicles, an oxygen sensor is only positioned in the exhaust pipe after the catalytic converter. Technician B says that the oxygen sensor provides the electronic body control module with an electrical signal that relates to the amount of oxygen in the exhaust gas. Who is correct?

Neither Technician A nor Technician B

A bidirectional scanner can do which of the following?

Operate various components and systems for test purposes.

In many cases, the software in the PCM's memory can be updated by uploading software updates, called a ______ process.

Reflash

Which of the following is often used as an actuator to control other actuators when the computer needs to control a high-current load?

Relays

A(n) ________ is a device able to electronically communicate with and extract data from the vehicle's one or more onboard computers.

Scan tool

In the engine management system, which of the following create input signals to the PCM?

Sensors

When DTCs are ________, the MIL will illuminate on the dash, indicating a fault.

Set

The speed-density method of determining the amount of air entering the engine takes into account all of the following EXCEPT:

Spark knock.

The purpose of the vehicle speed sensor is to measure the:

Speed of the vehicle.

Which of these pollutants has not decreased at least 30% since 1970 due to the regulation and effectiveness of the ODB system?

Sulfur dioxide

A fault code that begins with the letter "B" would MOST likely address a fault in the:

Taillight circuit.

Technician A says that the oxygen sensor is part of the feedback system for the engine management system. Technician B says that positive long-term fuel trims mean that the PCM is leaning out the fuel mixture from the base pulse-width setting. Who is correct?

Tech A

Technician A says that speed density systems use vehicle speed and fuel density to determine injector pulse width. Technician B says that mass airflow systems use a sensor to measure the mass of the air entering the engine. Who is correct?

Tech B

Technician A says that the oxygen sensor measures the amount of oxygen entering the intake manifold. Technician B says that many oxygen sensors have a built-in heater to warm them up more quickly. Who is correct?

Tech B

Technician A says that a closed loop system means the ECM is receiving feedback and adjusting the fuel injector on time as needed. Technician B says that lean means there is not enough air in the air fuel mixture. Who is correct?

Technician A

Technician A says that an open loop is when the PCM ignores the oxygen sensor signals. Technician B says that a closed loop is when the PCM shuts off the fuel injectors during a collision. Who is correct?

Technician A

Technician A says that potentiometer type sensors create a variable voltage signal that corresponds to a specific condition. Technician B says that oxygen sensors are the potentiometer type. Who is correct?

Technician A

Technician A says that some GDI engines may have two fuel pressure sensors. Technician B says that most fuel pressure sensors are mounted in the fuel tank. Who is correct?

Technician A

Technician A says that mass airflow sensors determine mass airflow based on engine speed and manifold pressure. Technician B says that some airflow sensors use a hot wire to determine mass airflow. Who is correct?

Technician B

In a vehicle, thermistors are used in various sensors related to:

Temperature

The feedback looping system in a three-way catalytic converter serves to adjust:

The air-fuel ratio.

Accessories not installed by the original equipment manufacturer (OEM) can be difficult to diagnose for all of the following EXCEPT:

The warranty may have expired.

A resistor that changes it's resistance with changes of temperature is called a:

Thermistor.

The potentiometer can be linear or circular in construction and has _______ electrical connecting points.

Three

Why is it important to run the monitors after repair?

To ensure that the fault does not immediately reoccur.

A scan tool detects a communications fault in the controller area network bus (CANbus). Which of these diagnostic trouble codes (DTCs) would MOST likely be stored?

U0021

The speed density method calculates the volume of air entering the engine, based on all of the following inputs EXCEPT:

Vehicle speed.