Electronic Fuel Systems Test 2

A good oxygen sensor normally swings between what two voltages?

.1-.9

How much compressed natural gas (CNG) does it require to achieve the energy of one gallon of gasoline?

122 Cubic Feet

The range of a trimming resistor is typically between __________.

30-300 Ω

How many rich/lean cycles should a good oxygen sensor make in five seconds?

7 to 8

A air/fuel ratio sensor will have a heater current of _________.

8-10 amps

E85 means that the fuel is made from ____________.

85% ethanol, 15% gasoline

Vapor Lock can occur

As a result of excessive heat near fuel lines If a fuel line is restricted

Where is the fuel pressure regulator located on a vacuum biased port fuel injection system?

At the outlet of the fuel rail

Oxygen sensors are being discussed, Technician A states an Air/Fuel ratio sensor can determine Air/Fuel ratios other than stoiciometric. Technician B states a conventional oxygen sensor only reports rich or lean not the ratio. Who is correct?

Both Tech A and B

Technician A states that going to high altitudes, engines produce lower power. Technician B states that most engine control systems can compensate the air-fuel mixture for changes in altitude. Who is correct?

Both Tech A and B

Technician A states that the research octane number is higher than the motor octane number. Technicain B states that the octane rating posted on fuel pumps is an average of the two ratings. Who is correct?

Both Tech A and B

Technician a states that spark knock, ping, and detonation are different names for abnormal combustion. Technician B states that any abnormal combustion raises the temperature and pressure inside the combustion chamber and can cause severe engine damage. Who is correct?

Both Tech A and B

Another name for a dual cell sensor is?

Current Pumping sensor

Adding propane to a vehicle is used for what purpose during oxygen sensor diagnosis?

Driving the sensor rich

Which type of port fuel injection system uses a fuel temperature and/or fuel pressure sensor?

Electronic Return less systems

A dirty Mass Air Flow sensor will cause positive fuel trim numbers at idle and negative fuel trim at higher speeds.

False

A vehicle powered with propane will have a higher fuel economy than the same vehicle powered with gasoline.

False

If the voltage of the heater switching circuit is measure at the sensor and it is toggling up to 8v and then back to zero this indicates a problem with the circuit.

False

If there is a vacuum leak fuel trim will be + ten or greater at idle and be normal at higher engine speeds.

False

Methanol has a higher heat content than gasoline.

False

The purpose of the trimming resistor is to compensate for sensor wear.

False

The snap throttle O2 test is done when the sensor voltage is as high as possible.

False

Toyota air/fuel ratio sensors reported a voltage of 0 to 1 on generic scan tools this made it easier for technicians to interpret the O2 signal.

False

Using E85 as a fuel increases fuel economy.

False

When the PCM is trying to overcome a rich condition fuel trim will display a positive number

False

If a vehicle has separate fuel control for each bank it must have how many oxygen sensors.

Four Total

The author recommends using what tool to diagnose oxygen sensors?

Lab Scope

Which alcohol is dangerous (toxic)? Methanol or Ethanol?

Methanol

Methynol is also called...

Methyl alchohol Wodd alcohol Methyl hydrate

A vehicle comes in with the MIL illuminated. The tech finds a code for an oxygen sensor malfunction Bank 2 sensor 1. Where is this sensor located?

On the bank opposite the #1 cylinder before the catalytic converter

The coworker blaimed what component at faulty?

PCM

What would the result be of using 87 octane fuel in a computer controlled vehicle that requires 91 octane fuel

Performance may suffer

Liquefied petrleum gas (LPG) is also called ________.

Propane

Dampeners are used on some fuel rails to _____________.

Reduce Noise

Why are some fuel rails rectangular in shape?

Reduces noise

Which fuel-injection system uses the MAP sensor as the primary sensor to determine the base pulse width?

Speed density

What type of device is used in a typical idle air control?

Stepper Motor

Ethanol can be produced from what products?

Switchgrass Sugarcane Corn

Which sensor has the greatest influence on injector pulse width besides the MAF sensor?

TP

Technician A states that the port fuel injection injectors operate using 5 volts from the computer. Technician B states that sequential fuel injectors all use a different wire color on the injectors. Who is correct?

Tech B

There was no current flow but the article mentions dynamic resistance of the heater element was too high. This indicates what type of fault.

The heater element was too high

When refueling a CNG vehicle, why is it recommended that the tank be filled to high pressure?

The range of the vehicle is increased

A faulty oxygen sensor may cause the vehciel to fail NOx emission test.

True

A good oxygen sensor should consistently and repeatedly cycle from rich to lean at 2000 RPM.

True

A good oxygen sensor should switch states when the throlttle is floored in less than .1 seconds.

True

A heater malfunciton code will set if the current is tool high or low.

True

A leaking injector will have a greater impact on fuel trim at idle than at higher engine speeds.

True

A rich condition could be caused by a faulty EGR valve.

True

A snap throttle O2 test is done to see how quickly the sensor responds to a quick change in air/fuel ratio.

True

According to the article fuel trim is a window that allows you to see what the computer is doing to controlfuel delivery and determine how the PCMS's adaptive strategy is working.

True

According to the article the best way to diagnose a Air/Fuel ratio sensor is with a scan tool.

True

An injector balance test can be performed on a vehicle without a fuel pressure gauge and an injector firing box.

True

Fuel pressure regulators may have a filter screen inside of regulator housing.

True

Gasoline has a shelf live of ninety days.

True

The PCM will increase and decrease current flow to the pump cell to maintain .45 volts in dual cell sensors.

True

Using ethanol-enhanced or reformulated gasoline can reduce fuel economy.

True

When a vehicle is first started short term fuel trim is at __________.

Zero

According to the artile a P0131 indicates the oxygen sensor is ___________.

failed low

Accoriding to the article when did the sensor fail?

fast idle

The best way to test an oxygen sensor is to _____________.

get it hot

What can be used to measure the alcohol content in gasoline?

graduated cylinder electronic tester

Winter-blend gasoline____________.

has a higher RVP can cause engine drivability problems if used during warm weather none of the responses are correct vaporizes more easily the summer-blend gasoline

Explain the purpose of eaach wire on a four wire zirconia oxygen sensor.

heater power, heater ground, sensor signal, sensor ground

The article mentions a third option for checking the sensor signal that is very different than normal testing, what was the test?

in series measuring mA with a DMM

Avoid topping off the fuel tank because ___________.

it can saturate the charcoal canister

When the front O2 sensor goes rich, how will the short term fuel trim react to this condition?

short term fuel trim will go lean

Operating the vehicle with less than a 1/4 of tank of fuel all the time will result in which of the following conditions

the fuel tank to rust the fuel pump life to be shortened by overheating water to build up in the tank

Why is a vacuum line attached to a fuel pressure regulator on many port fuel injected engines?

to create an equal pressure drop across the injectors