Engine performance Final

When checking the ECT sensor with a scan tool, about what temperature should be displayed if the connector is removed from the sensor with the key on, engine off?

-40°F (-40°C)

Typical TP sensor voltage at idle is about ________.

0.5 volt or 10% of WOT sensor voltage

Which type sensor uses a burn off circuit?

Hot wire MAF sensor Hot film MAF sensor

An IAT is being tested. After the vehicle has been allowed to cool for several hours, a scan tool is used to observe the IAT sensor reading. When compared to the engine coolant temperature (ECT), the two temperatures should be within how many degrees F of each other:

5

Which data set contains only two digits?

Binary

A customer states her MIL is blinking. Technician A says that this condition may damage the catalytic converter if the customer continues driving. Technician B says that freeze frame data should be stored. Which technician is correct?

Both A & B Blinking MIL light

Two technicians are discussing testing MAP sensors. Technician A says that voltage on a General Motors vehicle at idle should be about 1.0 volt. Technician B says MAP sensor frequency on a Ford vehicle at idle should be about 105-108 Hz. Which technician is correct?

Both tech Map sensors

A P0107 DTC is being discussed. Technician A says that a defective MAP sensor could be the cause. Technician B says that a MAP sensor signal wire shorted-to-ground could be the cause. Which technician is correct?

Both tech P0107

A P0102 DTC is being discussed. Technician A says that a sensor circuit shorted-to-ground can be the cause. Technician B says that an open sensor voltage supply circuit could be the cause. Which technician is correct?

Both tech p0102

When measuring the output signal of a MAP sensor on a General Motors vehicle, the digital multimeter should be set to read ________.

DC volts

When testing an ECT sensor on a vehicle, a digital multimeter can be used and the signal wire back probed. What setting should the technician use to test the sensor?

DC volts

Which of these is a continuous monitor?

Fuel system monitor

DTC P0302 is a ________.

Generic DTC

Technician A says that MAP sensors use a 5-volt reference voltage from the PCM. Technician B says the MAP sensor voltage will be higher at idle at high altitudes compared to when the engine is operating at near sea level. Which technician is correct?

Tech A 5 Vref

Technician A says that the 3 wires on the TP sensor include a 5-volt reference voltage from the PCM Technician B says that a TP sensor is a three-wire variable resistor called a rheostat. Which technician is correct?

Tech A 5 volt reference

An ignition misfire or fuel mixture problem is an example of what type of DTC?

Type A

Which sensor has a switch that controls the electric fuel pump?

VAF

What unit of electricity is used as a signal for a computer?

Volt

A freeze frame is generated on an OBD-II vehicle ________.

When a type A or B diagnostic trouble code is set

The MIL is turned off if ________.

Power to the PCM is disconnected The vehicle is driven on three consecutive trips with a warm up cycle and meets all code set conditions without the PCM detecting any faults The codes are cleared with a scan tool

Which computer function describes how the computer handles inputs?

Process

Global (generic) OBD II contains some data in what format?

Roman Numerals

Two technicians are diagnosing a poorly running engine. There are no diagnostic trouble codes. When the MAF sensor is unplugged, the engine runs better. Technician A says that this means the MAF is supplying incorrect air flow information to the PCM. Technician B says that this indicates the PCM is defective. Which technician is correct?

TECH A incorrect MAf info

Which of the following components provides the engine control computer with engine coolant temperature information?

Engine coolant temperature sensor

A ________ is a variable-resistance sensor with three terminals.

Potentiometer

What two things can a vehicle computer actually perform (output)?

Turn something on or turn something off

An O2S (Oxygen sensor) is being tested using a DSO (digital storage oscilloscope). A good oxygen sensor should display how many switches per second?

1-5

The frequency output of a digital MAP sensor is reading 114 Hz. What is the approximate engine vacuum?

15 in. hg

How many terminals are in an OBD-II data link connector (DLC)?

16

OBD-II has been on all passenger cars in the United States since ________.

1996

Most TP sensors have how many wires?

3

The typical MAF reading on a scan tool with the engine at idle speed and normal operating temperature is ________.

3-7 grams per second

A typical TP sensor registers how many volts at WOT (wide open throttle)?

4.5 V

The computer will automatically clear a DTC if there are no additional detected faults after ________.

40 consecutive warm up cycles

A low O2S voltage could be due to ________.

A lean exhaust A defective spark plug wire

A typical MAP sensor compares the vacuum in the intake manifold to ________.

A perfect vacuum

A high O2S voltage could be due to ________.

A rich exhaust

Which airflow sensor has a dampening chamber?

A vane airflow

Analog signals from sensors are changed to digital signals for processing by the computer through which type of circuit?

AD converter

What does the post, or downstream, oxygen sensor (HO2S) measure?

Amount of oxygen behind the catalytic converter

Technician A says that other temperature sensors that operate like the ECT (engine coolant temperature) include transmission fluid temperature (TFT), and engine oil temperature. Technician B says that all temperature sensors increase in resistance as the temperature decreases. Which technician is correct?

Both techs

Technician A says that the 3 wires on the TP sensor include a 5-volt reference voltage from PCM, plus the signal wire to PCM, and ground. Technician B says that the TP sensor is used by the PCM to determine torque converter engagement and transmission shift points. Which technician is correct?

Both techs TP Sensor

A MAF sensor on a General Motors 3800 V-6 is being tested for contamination. Technician A says that the sensor should show over 100 grams per second on a scan tool display when the accelerator is depressed to WOT (wide open throttle) on a running engine. Technician B says that the output frequency should exceed 7000 Hz when the accelerator pedal is depressed to WOT on a running engine. Which technician is correct?

Both techs contaminated MAF sensor

Technician A says that oxygen sensors can have one, two, three, four, or more wires, depending on the style and design. Technician B says if the exhaust has little oxygen, the voltage of the oxygen sensor will be close to 1 volt (1000 mV) and close to zero if there is high oxygen content in the exhaust. Which technician is correct?

Both techs oxygen sensors

The "brain" of the computer is the ________.

CPU

Which design of MAP sensor produces a frequency (digital) output signal?

Capacitor-capsule

The ratio of on time relative to the period of the complete cycle is the ________.

Duty Cycle

The sensor that most determines fuel delivery when a fuel injected engine is first started is the ________.

ECT (engine coolant temperature) sensor

All OBD II vehicles use what type of read-only memory?

EEPROM

Which term describes a set of conditions required to allow each monitor to run?

Enabling criteria

Technician A says that the purpose and function of the (IAT) intake air temperature sensor is to provide the engine computer (PCM) with the temperature of the air entering the engine. Technician B says that the IAT sensor information is used for fuel control (adding or subtracting fuel) and spark timing, depending on the temperature of incoming air. Which technician is correct?

IAT sensor both techs

Which computer function is defined as a voltage signal from a sensor or switch?

Input

The four basic computer functions include ________.

Input, processing, storage, and output

The SAE J-1930 standardized name for the sensor that measures the temperature of the air being drawn into the engine is called a(an) ________.

Intake air temperature sensor (IAT)

A large amount of oxygen in the exhaust system causes the O2S (Oxygen sensor) to produce which of these?

Low voltage

Which of these sensors does the TP sensor back up if the PCM determines that a failure has occurred?

MAF or MAP sensors

Which is NOT a purpose or function of the MAP sensor? Helps diagnose the EGR system Measures engine load Measures engine speed Calculates fuel delivery based on altitude

Measures engine speed

A technician attaches one lead of a digital voltmeter to the ground terminal of the TP sensor and other meter lead to battery negative terminal. The ignition is turned on, engine off and the meter displays 37.3 mV. Technician A says that this is the signal voltage and is a little low. Technician B says that the TP sensor ground circuit has excessive resistance. Which technician is correct?

Neither Tech TP sensor

Technician A says that the ECT and IAT sensors can be tested visually, as well as by using a digital multimeter or a scan tool. Technician B says that the ECT sensor is a high-authority sensor at engine startup and is used for open-loop control, as well as idle speed. Which technician is correct?

Neither tech A or B.

Two technicians are discussing Karman Vortex sensors. Technician A says that they contain a burn-off circuit to keep them clean. Technician B says that they contain a movable vane. Which technician is correct?

Neither tech Karman Vortex

The sensor that must be warmed and functioning before the engine management computer will go to closed loop is the ________.

O2S

When testing the ECT sensor with the connector disconnected, the technician should select what position on the DMM (digital multimeter)?

Ohms

Where is sensor 1, bank 1 located?

On the same bank where number 1 cylinder is located In the exhaust manifold

The comprehensive component monitor checks computer controlled devices for ________.

Opens Shorts-to-ground Rationality

By looking at the way diagnostic trouble codes are formatted, which DTC could indicate the gas cap is loose or defective?

P0042

The SAE term for the vehicle computer is ________.

PCM

Technician A says that an oxygen sensor produces a voltage output signal based on the oxygen content of the exhaust stream. Technician B says that if the exhaust has little oxygen the voltage of the oxygen sensor will be close to 0 volts. Which technician is correct?

Tech A oxygen sensor

Two technicians are discussing the IAT sensor. Technician A says that the IAT sensor is more important to the operation of the engine (higher authority) than the ECT sensor. Technician B says that the PCM will add fuel if the IAT indicates that the incoming air temperature is cold. Which technician is correct?

Tech B IAT sensor

Technician A says that oxygen sensors can be tested using a test light or dwell meter, or a scan tool. Technician B says conditions can occur that cause the oxygen sensor to be fooled and give a false lean or false rich signal to the PCM. Which technician is correct?

Tech B oxygen sensors

Two technicians are discussing a stepped ECT. Technician A says that the sensor used for a stepped circuit is different than one used in a non-stepped circuit. Technician B says that a stepped ECT circuit uses different internal resistance inside the PCM. Which technician is correct?

Tech B stepped ETC

Which of these components lets the PCM know how fast you want to accelerate?

Throttle Position (TP) Sensor

Which item is a computer input sensor?

Throttle position angle RPM Engine coolant temperature

Which item is a computer output device?

Transmission shift solenoid Fuel injector Evaporative emission control solenoid

A generic scan tool can access the same information at the same rate as an enhanced original equipment manufacturer's scan tool T/F?

True

Absolute pressure is equal to barometric pressure plus intake manifold vacuum. t or f

True

A heated Zirconia oxygen sensor will have how many wires?

either 3 or 4

Air that enters the engine without passing through the airflow sensor is called ________.

false air

As the load on an engine increases, the manifold vacuum decreases and the manifold absolute pressure ________.

increases

The voltage output of a zirconia oxygen sensor when the exhaust stream is lean (excess oxygen) is ________.

relatively low (close to 0 volt)

A fuel injection system that does not use a sensor to measure the amount (or mass) of air entering the engine is usually called a(an) ________ type of system.

speed density