WS6 Oxygen Sensor on Vehicle

WS6

Oxygen Sensors on Vehicle

Name ......................................... Date……………..

Make Toyota Model 1ZZ engine.Year ................

1.0 Locate Oxygen Sensor

1.1 Locate an oxygen sensor on your vehicle. Describe where it is

located:

In this engine the O2 sensor is located befor CAT on exhast cahamber

just where the exhast goes leave from the cylender.

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1.2 How many wires for this oxygen sensor? three wires

1.3 Record the colors for each of the wires at the sensor side of the

connector (not the ECU side of the connector). Then list the use

of the wires. Usually a black or blue wire will be the O

signal, Grey may be the sensor ground. Heater power and

ground are often white. But there may be other colors. You may

have to consult a wiring diagram.

Colour Use or Purpose

White …Power supplay

Whote ...Signal

Black … Ground

……….. ………………………

1.4 What type of Oxygen Sensor is this? (tick one)

Zirconia switching sensor? Zircnia sswitch sensor

Titania switching sensor? …….

Broadband Air Fuel Ratio sensor? (one cell) …….

Broadband Air Fuel Ratio sensor? (two cell) …….

This worksheet is designed for switching type sensors only. If

you have a broadband sensor, see your lecturer for another

worksheet.

2.0 Back probe the Oxygen Signal Wire

an oscilloscope.

lecturer or other help sources. Check that you are connected to the

Oxygen sensor signal: Run the engine and check that you are

seeing a signal. Connected OK? YES OK

with a pin and connect toIf you need help using the oscilloscope see your

3.0 Watch and Record Oxygen Signal pattern at 2500 rpm.

the engine warm up and enter closed loop so you see a normal

cycling pattern. You may have to hold the rpm about 2500 for half a

minute to go into closed loop.

3.1 Freeze your pattern and draw or photograph it onto the

graph below: Note the voltage and time per division or scale

3.2 How high does the voltage go?0.81 V0lts

3.3 How low does the voltage go? 0.38 volts

3.4 What is the average voltage? (Some oscilloscopes have

functions that will calculate the average for you. If not, just

guess.)up to 5 volts

3.5 How many

seconds? (One cross count is when it goes from high to low, or

from low to high.) List here:0.35 V -to 0.891 volts.

3.6 If the signal is not cycling normally, describe what the signal

does:
The cycling is normal.

4.0 Watch and Record Oxygen Signal pattern at Idle rpm.

engine warm up and enter closed loop so you see a normal cycling

pattern. You may have to hold the rpm about 2500 for half a minute

to go into closed loop. Then let the RPM come down to idle.

4.1 Freeze your pattern and draw or photograph it onto the

graph below: Note the voltage and time per division or scale

At 2500 rpm get the voltage 0.266 volts

4.2 How high does the voltage go?0.66 volts 

4.3 How low does the voltage go? 0.891 volts

4.4 What is the average voltage? (Some oscilloscopes have

functions that will calculate the average for you. If not, just

guess.) 0.5 volts

4.5 How many

seconds? (One cross count is when it goes from high to low, or

from low to high.) List here: 12

4.6 If the signal is not cycling normally, describe what the signal“Cross Counts” does the signal have in 10does.Cycling is normaly.

5.0 Make this Oxygen Sensor go rich

twice. (The fuel system should normally make the system go rich

when you do a sudden acceleration.) Push on the accelerator

quickly but

by accelerating once ordon’t let the rpm go high enough to hurt the engine.

(If you act like you will hurt the engine you will be asked to leave

lab.) The signal should go over 0.85V.

5.1 Freeze your pattern as it goes rich and draw or photograph

it onto the graph below: Note the voltage and time per division

or scale next to the graph.

5.2 How high does the Oxygen sensor voltage go? 784 volts

5.3 If this signal is not going high normally, describe what the signal

does:

It went high at once at the time of high acceleration of the engine and the but that when we let it free, the signal stayed average about 0.7 V for two seconds

6.0 Make this Oxygen Sensor go lean

deceleration. Gently run the rpm up to about 3,000, and let the

RPM drop suddenly. The fuel system should make the system

go lean on deceleration. The signal should go below 0.2V.

6.1 Freeze your pattern as it goes rich and draw or photograph

it onto the graph below: Note the voltage and time per division

or scale next to the graph

6.1 How low does the Oxygen sensor voltage go?0.037 volts

6.2 If this signal is not going low normally, describe what the signal
If this signal is not going high normally, describe what the signal does?

A. It was normal when the engine was Idle. Once we accelerate the engine, the voltage dramatically dropped down close to zero volt or we can say close to 0.1 V and stayed there for few second, about two seconds, before jumping up to.

7.0 Measure the Response Time

that the sensor can respond quickly to changes in the exhaust gas.

The best way is to do a sudden acceleration, freeze the pattern, and

measure how long it took the sensor to go from lean to rich.

7.1 Freeze your pattern as it goes suddenly rich from a lean

condition and draw it into the graph below: Normally you want

the voltage to go from below 0.2V to above 0.8V. in less than

100 ms. Note the voltage and time per division or scale next toof the sensor. You want to knowthe next graph

7.2 Measure how long the sensor took to go from lean to rich.

Use the cursers on the scope if necessary. Record how long

the sensor took here: 0.05 volts

8.0 Discuss how a normal Zirconium oxygen sensor works: draw a

picture below to help show how it works?

This type of oxygen sensor has been in service for longest time its made of zirconia ( ziconim oxide) platinium electrodes and a heate the O2 sensor generate a voltage signal based the amount of oxygen in the exhasust compeared to atomospheric oxygen.
The zicronia element has one side  to exahust strem the other side open to the atmospheric each side has platinuim electrode to zironic dioxide element.


Contamination or corossion of the platinium electrodes or zirconia element will reduce the voltage signal output.

 by doing a suddenLet the“Cross Counts” does the signal have in 10Let2 sensor