INPUTS
Inputs are signals from sensors all around the engine that the ECU relies on to keep the engine efficiently and smoothly.
The first sensor tested was the TPS (throttle position sensor) this test is done with engine off but ignition on, first the throttle was tested when it was closed or at the idle position, it gave a reading of 0.5 volts then the throttle was opened up fully and the sensor gave a reading of 3.9 volts. The TPS sends the voltage to the ECU (electronic control unit) as a signal this allows the ECU to calculate how much air could be going into the motor and adjust the fuel injected into the combustion chamber correspondently to keep the air/fuel ratio at stoichiometric mixture which is 14.7:1 or 14.7 parts of air to one part of fuel. Stoichiometric must be kept as this is usually the most efficient ratio for the motor to run on. The greater voltage or signal that the ECU receives the more fuel the ECU keeps the fuel injectors open to keep the correct air/fuel ratio. If the TPS is faulty i.e. there is flat spot where bad contact is being made and the TPS tells the ECU that the throttle is open less than what it actually is this could cause a power lag as the air/fuel mixture would be to lean because not enough fuel is being injected into the combustion chamber and the engine would be down on power for a brief moment.
The next was done when the engine was running but this is done immediately when it is cold so that it can compared with when the engine was warm. This test was on the coolant temperature sensor, when the engine or coolant is cold the sensor sends 2.5 volts to the ECU and when the engine has warmed up, the sensor sends 0.5 volts to the ECU the greater voltage is sent to the ECU when the engine is cold so that the ECU knows what temperature the engine is and therefore whether the engine needs a rich air/fuel mixture when it is cold. The engine needs a rich air/fuel mixture when it is cold as fuel condenses on the cold surfaces of the combustion chamber and the fuel loses its explosive abilities a rich air/fuel mixture would be 12:1 or less. So more fuel is injected so that there is still enough fuel to keep the engine running when it is cold. Once the engine has warmed up the coolant temperature sends less voltage to the ECU this is so that the ECU knows that the engine has warmed up and not as much fuel needs to be injected now because the fuel cannot condense on the hot combustion chamber walls and now less fuel is required to keep the engine running as none of it is condensing and all of it can combust. If there is something wrong with the coolant temp. sensor then the ECU does not know whether the engine is cold or warm and cannot give the correct air/fuel ratio this could cause the engine to run rough as it the engine could run to lean and fuel won't be as combustible. A lean air/fuel mixture would be 17:1 or more. If the coolant temperature sensor is not working properly then the engnie does not know what temperature the engine is running at and it the ECU does not know whether to run the air/fuel ratio rich or lean for the engine temperature and this could make the engine very inefficient as it is running a rich mixture and a lot more fuel is being used but the engine power will increase with this. But the engine could run roughly as it could run the engine to lean and fuel might lose its ability to be explosive causing a miss fire.
The next test was to check the crank shaft and cam shaft sensors otherwise known as an RPM sensor as these sensors are usually located in the distributor of cars that have ECU's but do not have coil over plug arrangements, these sensors are usually tested by setting the multimeter to ACV (alternating current voltage) then checking both the crank shaft sensor and the cam shaft sensor whilst the engine is running. Then check the Hz (hertz) for the two sensors by setting the multimeter to Hz. The crankshaft and camshaft sensors purpose to let the engine ECU know at what point the engine is so that it knows when to fire the spark plugs and the fuel injectors. At idle the crankshaft sensor should read about 0.8v(ac) and the camshaft 0.25v (ac), and the Hz should be about 37Hz for the crankshaft sensor at idle and 80Hz at 2500RPM and at idle the camshaft sensor should be 20Hz it shouldn't increase to much more when the engine is at revs. If either the crankshaft sensor or the camshaft sensor fail then the engine will not run because these sensors tell the engine where the crankshaft is located or piston position, and the camshaft sensor tells the ECU what stroke the cylinder is on whether it be intake, compression, power or exhaust. This sensor lets the ECU know when to inject fuel and when to fire the spark plugs if the arrangement is coil over plug.
The next sensor to be tested was the MAP (Manifold Absolute Pressure) sensor, this measures the vacuum in the intake manifold, when the engine is at idle the voltage from the MAP sensor should be quite low as air pressure in the manifold is low but vacuum should be very high. The voltage should increase as the throttle opens up more and air pressure in the intake manifold increases or as vacuum decreases. The MAP sensor tells the ECU how much air is going into the engine and it can then control how much fuel is injected into the combustion chamber to keep the correct air/fuel ratio.
The last sensor to be checked was the air temperature sensor, first it must be checked when the engine is cold which should be around 2.5 volts or more if the outside air is relatively warm and decrease to 2.3 volts or less when the engine has warmed up. The purpose of the air temp. sensor is to let the ECU know the temperature of the air going into the engine, this is because during cold conditions air is much more dense and therefore more fuel is required to keep the correct air/fuel ratio, however in hot conditions air is less dense and there is less of it so less fuel is required to be injected to keep the correct air/fuel ratio.
OUTPUTS
Outputs are what the ECU controls based on what it recieves from its input sensors.
The next test was to measure the fuel injector cycle which is an output from the ECU, this is done by setting the multimeter to duty cycle % and setting it to the negative voltage, with the engine and at idle the reading should about 5%, that is the fuel injector is only 5% of the time as only a small amount of fuel is required to keep the engine running, however when the engine is under acceleration the injectors on time should increase to about 15% depending on how much acceleration is required as more fuel is required to help the engine accelerate and increase its revs. The percentage is the on time of the injector compared to its off time.
The last test was the Idle Air Control sensor, the idle air control sensor regulates the engines idle speed by adjusting how much air is allowed passed the closed throttle valve, the ECU can control the idle speed by signals from other sensors. Like when the engine is cold and it needs to rev a bit higher more air is allowed passed the closed throttle valve to let the engine rev more so that it does not stall. The idle air control sensor can be checked by setting the multimeter to duty cycle % and setting it to negative voltage the meter should read about 35% when the engine is idling.
Another output from the ECU that can be tested but didn't show in the sheet is testing coils. This can only be done on coil over plug motors, to test this set the multimeter to duty cycle % and set it to positive voltage as this measures when it sparks. The reading at idle should be about 3% on time compared to off time, this number should not change when the engine is revving as spark duration does not need to change to effectively ignite the air/fuel mixture in the combustion chamber. The reason that manufacturers went to coil over plug arrangements is that now one coil controls one cylinder where as before one coil controlled multiple cylinders. This means that coil gets more time to charge up and create a strong magnetic field so that when the magnetic field collapses a stronger spark is created. When there was just one coil it could not effectively create a strong spark at higher revs because the coil could not charge up enough to create a strong spark, so the main benefit of coil over plug is that strong sparks can still be created at high rpm and engines will not lose any power.
Sensors.
Throttle position sensor
A throttle position sensor (TPS) is a sensor used to monitor the position of the throttle in an internal combustion engine. The sensor is usually located on the butterfly spindle so that it can directly monitor the position of the throttle valve butterfly.
The sensor is usually a potentiometer, and therefore provides a variable resistance dependent upon the position of the valve (and hence throttle position).
The sensor signal is used by the engine control unit (ECU) as an input to its control system. The ignition timing and fuel injection timing (and potentially other parameters) are altered depending upon the position of the throttle, and also depending on the rate of change of that position. For example, in fuel injected engines, in order to avoid stalling, extra fuel may be injected if the throttle is opened rapidly (mimicking the accelerator pump of carburetor systems).
Air temp sensor
An air temperature sensor is used on fuel injected engines. The purpose of an air temperature sensor is to help the computer calculate air density. A change in temperature changes the resistance in the sensor. Simply stated, the higher the air temperature gets the less dense the air becomes. As the air becomes less dense the computer knows that it needs to lessen the fuel flow. If the fuel flow was not changed the engine would become rich, possibly losing power and consuming more fuel. The temp sender is generally located in the air inlet tube or the air box. The wire running to the sensor can be disconnected then the sensor can be unscrewed and replaced. Some aftermarket companies trick this sensor with a resistor (false temp reading) to make the engine run richer. If a engine has been tuned lean this trickery can show mild power gains.
Oxygen sensor
An oxygen sensor, or lambda sensor, is an electronic device that measures the proportion of oxygen (O2) in the gas or liquid being analyzed. The most common application is to measure the exhaust gas concentration of oxygen for internal combustion engines in automobiles and other vehicles. Divers also use a similar device to measure the partial pressure of oxygen in their breathing gas.
Crankshaft position sensor
The Crankshaft position sensor also known as the crank position sensor is an electronic device used in an engine to record the rate at which the crankshaft is spinning.
This information is used by the ECU to control ignition and fuel injection. The sensor system consists of a rotating part, typically a disc, as well as a static part, the actual sensor. Typically a Hall Effect sensor is used as the static part requiring a magnet to be mounted somewhere in the periphery of the rotating disc, but other detection principles can also be employed i.e. optical or inductive.
The functional objective for the crankshaft position sensor is to determine the position and rotational speed (RPM) of the crank. Engine management systems use the information transmitted by the sensor to control things such as ignition timing and fuel injection timing. The sensor output can also be related to other sensor data including the cam position to derive the current combustion cycle. While there are several competing objectives in the fuel injection system it was primarily designed for controlling and improving.
MAP sensor
The map sensor uses a relative vacuum measurement and has a different range. The map is important for many reasons and usually every fuel injected vehicle will have one of these. The baro sensor is used as a secondary system so that even slight atmospheric changes can be monitered by the engine. Air density changes, as the pressure increases the engine will go lean. The sensor tells the ecu, which adds fuel to correct the lean condition. If your map sensor seems to be malfunctioning you can test it. First check for a loose plug or a bad vacuum hose.
MAF sensor
The mass air flow sensor (MAF) is used to monitor the amount of air going into the engine while running. Mass air flow sensors work in conjunction with the oxygen sensor and the engine control system to maximize performance and economy. A vehicles mass air flow sensor delivers a signal to the PCM computer ( power train control module) telling the amount of air coming into the engine. This is compared with oxygen levels in the exhaust to determine the efficiency of the engine. It is usually difficult to detect when a mass air flow sensor fails, the "check engine light" or engine symbol will probably not be illuminated. your car , truck or SUV may have a poor idle quality, stall, low or all three. Your PCM may have no trouble codes because the PCM cannot detect a problem since the sensor is working but is out of range.
WES General Lab Scope Tests
Signal Name throttle Position Sensor
Volts/Division/range: 2
Time /division/range: 500 ms
Explain the operation of the sensor or device using the graph:
At position one the throttle position sensor are at 0.407v and as the was open the voltage then it rose to 3.796v as position 2 includes .
At position 3 the voltage remained the at 3.796 and as the throttle close and decreased back to 0.407v as position 4 includes.
WES General Lab Scope Tests
Signal Name Vacuum sensor
Volts/Division/range: 1
Time /division/range:
Explain the operation of the sensor or device using the graph:
Up until position 1 the engine is idle and the vacuum is going of stable reading 1.415v
As the engine is reduced you see at position 2 the voltage from the sensor has resin to 3.431
this is due to lower vacuum which creates less resistance on the sensor.
As the engine deaccerelate until position 3 we can see voltage drop lower then what it was when it was idling this is due to the throttle body being closed and engine shall deceleration which creates a lower pressure and higher vacuum . At point 5 we can see the vacuum stablising back to its original voltage.
WES General Lab Scope Tests
Signal Name Air temp sensor
Volts/Division/range: 1v
Time /division/range: 5
Explain the operation of the sensor or device using the graph:
At position one the air temp sensor was showing voltage of 1.014v at this point the we used a heat gun to begin to hot air into the air box, this resulted gradual decrease in voltage .
At position 2 the heat gun was then removed and we had a reading of 0.832v .
After the heat gun was removes the voltage gradualy increased as the temp decreased and at point 3 the air temp sensor had gone back to its normal temp.
WS2 Flash Codes
Warning: Be careful working around engines and exercise caution to avoid injury.
Note: The engine check light must be working.
If you have problems with the task, see you lecturer for help.
1. Flash/Blink Codes
1.1 Find a engine/vehicle that you have the workshop manual with the correct procedure and codes to diagnose the flash codes
1.2 Have your tutor create a fault in the EFI system
1.3 Using the workshop manual follow the procedure to extract the codes, explain briefly what is the procedure
To get a fault code on car you first need to trun the engine off,then trun the key ,off,on,off,on without starting the engine .
The codes will begin to flas on the check engine light .
The light will blink numbers og first digit, pause and blink the number second digit.
All codes are 2 digit numbers.The code 55 indicates the end of the massage .
As an example a stord code of 23 would flash 2 time pause, first 3 times,pause, flash 5 times and flsh 5 times.
To get rid of these codes you can disconnect main engine fuse or you can also unplug the negative battery termainl for 30 second or more.
once you done that the flash codes should be gone..trun the engine on and check engine light will continuly flash once you see that this means the fault codes has gone and its all clear.
1 Trouble Codes or Fault Codes
1.1 Find where the Codes are listed
1.2 Record any codes, and what system and condition they describe in the chart below (Example: might be code number 21, for Throttle Position Sensor, signal voltage too low)
Code number | System affected | Condition described |
22 | Water temp sensor | engine runs rough low voltage |
41 | TPS circuit | enigne runs rough no voltage |
31 | Vacuum sensor | low voltage engine runs rough |
24 | Intake air temp | miss fires |
3 Visual Inspection to find fault
3.1 Do a visual inspection under the bonnet to find where the problem is. Use information from the code to know where to look for the problem and what type of problem to look for.
3.2 Describe the problem(s) you found:
when i doing my visual inspection i found the water tem circuit , TPS circuit,
vacuum sensor and also the intake air temp circuit were disconnectd .
3 Repair fault
3.1 Plug back in the connector, or repair problem found
Describe what you did:
I recheck all the faults again and the plug them back in and then i disconnect
the negative battery termainl for 30 second and put it back on and trund the
engine on and the check engine light was flashing that means the codes
were all cleard.
5 Clear Codes
Describe what you did to clear the codes:
i made the disconnection of the negative battery terminal for 30 senonds or more
or you can also disconnet the main engine fuse for 30 seconds once you done
that the codes should be all cleard.
6 Recheck for codes and record codes in system now:
I recheck the codes and there were no codes which means the
codes were all cleard.
7 How could the faults found affect the engine performance?
The engine wouldnt run propley which means low engine performace
and it could also create other problems if its not fixed .
8 Discuss what other tests you should be doing once you have found the fault codes:
After i done all that i check the voltages unsing multimeter to see if the
voltage is wthin its manufacture spection on all the sensor that were all
faulty.
WS8 Primary & Secondary Ignition Patterns
Warning: Ignition coils create high voltage. It can be dangerous, so avoid getting too close to ignition parts when engine is running. Make your connections when the engine is off, and then keep your distance when the engine is running. Even some primary voltage is high enough to stop a “Pacemaker”.
Also: Do not run engines with secondary ignition HT leads “open circuit”. Make sure they are grounded to engine through a spark plug, grounding wire, or spark tester.
If you have problems with the task, see you lecturer for help.
1.0 Primary Voltage Patterns
1.1 Set up a lab scope or ignition oscilloscope to view the primary ignition pattern (in parade or display mode) on your lab scope, with the engine warmed up and idling.
1.2 Record the average Firing Voltage (or “Step Up voltage) for each cylinder in the chart below. Some variation is normal, just pick the average. If you don’t understand what this is, review the resource information available.
1.3 Record the average Burn Voltage for each cylinder in the chart below.
1.4 Record the average Burn Time in milliseconds for each cylinder in the chart below.
1.5 Record the average Dwell Time for each of the cylinders in the chart below. What unit of measurement are you using to measure the dwell time?
1.6 Are all these primary ignition voltage readings normal? (Yes) Please discuss what is normal or abnormal about this pattern and what causes it?
The voltage reading were normal and dwell time looked good as it allowed the coil to change properly to create a stonge magnetic field.
When the field collapsed over the second winding high voltage wa indvced creating a voltage spike which is normal. then trun time was measured which is time to spark is created.
Cyl 1 | Cyl 2 | Cyl 3 | Cyl 4 | Cyl 5 | Cyl 6 | Primary Ignition |
NA | NA | Firing Voltage | ||||
Burn Voltage | ||||||
NA | Burn Time | |||||
NA | Dwell Time |
1.7 Draw or photograph the Primary Ignition oscilloscope parade pattern from your scope into the box below. Do it carefully and show the detail you need to see for diagnosis. Record voltage and time scales.
the Dwell part of the pattern. This is where the coil is actually turned on by the vehicle's control module. The coil is building up a strong magnetic field to spark the spark plug during this part of the pattern.
3 is the part of the pattern where the spark is actually firing. The initial spark uses the most voltage, as the spark is generated less voltage is needed to maintain the spark and the voltage drops. The amount of time the spark stays active and the amount of voltage needed to keep the spark going can give you clues as to what's going on inside the cylinder. A low starting spark line could indicate that that the spark plug could be oil fouled, that a short in the spark plug wire is present, or that the cylinder compression is low.
3 is the part of the pattern where the spark is actually firing. The initial spark uses the most voltage, as the spark is generated less voltage is needed to maintain the spark and the voltage drops. The amount of time the spark stays active and the amount of voltage needed to keep the spark going can give you clues as to what's going on inside the cylinder. A low starting spark line could indicate that that the spark plug could be oil fouled, that a short in the spark plug wire is present, or that the cylinder compression is low.
5 to 6 is the part where the coil is turned off and the magnecit field that the coil has generated is now collapsing. You can get an idea what shape your coil is in by watching the osolations just after the spark plug is done firing. If there are fewer than four osolations at this part of the pattern then there could be some shorting in the coil.
1.10 Some scopes have the facility to use raster or stacked display. How could this help you to diagnose a fault. What can you see more clearly?
I can control the size of voltage and time and the waveform can be bigger, so I can see more clearly with detail information.
2.0 Secondary Voltage Patterns
2.1 Set up your ignition oscilloscope or lab scope to view the secondary ignition patterns on your lab scope, with the engine warmed up and idling. (Use parade mode or individual mode on each different cylinder, depending on scope available.)
2.2 Record the average Firing Voltage (or “Step Up voltage) for each cylinder in the chart below. Some variation is normal, just pick the average. If you don’t understand what this is, review the resource information at the back of this worksheet.
2.3 Record the average Burn Time for each cylinder in the chart below.
Are all these secondary ignition voltage readings normal? Yes Discuss what is happening in the pattern and what it is telling you about the ignition system.
From the secondary ignition pattern, firing voltages were at 2 to 5 kv in cylinders and burn times were at 1.5ms in three cylinders and #4 cyl was at 1.7ms. As a result, secondary ignition pattern is slightly differnt but these patterns are normal with correct values.and we showed it to our
teacher to see if you got the right reading or not.
2.5 Do a Snap Acceleration (don’t damage the engine by revving too high or for too long) and record in the chart below how high the Firing Voltage (KV) went under Snap Acceleration.
Cyl 1 | Cyl 2 | Cyl 3 | Cyl 4 | Cyl 5 | Cyl 6 | Secondary Ignition |
Firing Voltage (KV) | ||||||
Burn Time (ms) | ||||||
Snap Acceleration |
2.6 Are all these Snap Acceleration secondary ignition voltage readings normal? Yes Discuss what is happening and what the pattern is telling you.
When we were doing the snap acceleration is added, the firing voltage slightly increased. This means that higher rpm needs higher firing voltage with short burn time.This was also checked by our teacher to make sure we got it correct.
2.7 Draw or photograph the Secondary Ignition lab scope pattern while idling from your scope into the box below. Do it carefully and show the detail you need to see for diagnosis.
2.8 If you can safely do this, (with the engine stopped), gently disconnect one spark plug wire, and short to the engine with a jumper wire. Which cylinder number did you short? 3
2.9 Start the engine and let it idle (for only a short time.) Record the new Firing Voltage and Burn Time for all the cylinders in the chart below.
Cyl 1 | Cyl 2 | Cyl 3 | Cyl 4 | Cyl 5 | Cyl 6 | Secondary Ignition (one cylinder grounded) |
4kv | Firing Voltage (KV) | |||||
1.5 ms | Burn Time (ms) |
2.10 Draw or photograph the shorted Secondary Ignition waveform you see now on your scope.
2.15 Stop the engine, remove the spark tester (be gentle), replace the spark plug wire, and run the engine to clear the spark plug. The engine should be back to normal now. If not, tell your lecturer.
2.16 Discuss what happens to the ignition waveform when the spark tester is attached to the spark plug wire. What does it tell you about the ignition system.
2.16 Discuss what happens to the ignition waveform when the spark tester is attached to the spark plug wire. What does it tell you about the ignition system.
When the spark tester is located at 20 kv (bigger spark gap) in #4 cyl , the firing voltage increases to 6 kv and the burn time decreases to 1.3ms because there was a bigger spark gap.
As a result, the firing voltage and burn time are related to the spark gap. If spark gap is small the firing voltage will decrease and the burn time will increase. On the other hand, if spark gap is big the firing voltage will go up and the burn time will drop.
2.17 Remove the spark tester carefully, and put everything back together on the engine. Engine runs fine? yes. If any problems with vehicle, please tell your instructor.
WS6 Oxygen Sensors on Vehicle
Make FORD Model KA
1.0 Locate Oxygen Sensor
1.1 Locate an oxygen sensor on your vehicle. Describe where it is located:
The oxygen sensor is located the top of the exhaust manifold in front of the engine.
1.2 How many wires for this oxygen sensor? 4
1.3 Record the colours 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 O2 sensor signal, Grey may be the sensor ground. Heater power and ground are often white. But there may be other colours. You may have to consult a wiring diagram.
1.3 Record the colours 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 O2 sensor signal, Grey may be the sensor ground. Heater power and ground are often white. But there may be other colours. You may have to consult a wiring diagram.
Colour Use or Purpose
White heater +
White heater +
White heater -
Black signal positive
Grey signal ground
1.4 What type of Oxygen Sensor is this? (tick one)
Zirconia switching sensor? …√….
Titania switching sensor? …….
Broadband Air Fuel Ratio sensor? (one cell) …….
Broadband Air Fuel Ratio sensor? (two cell) …….
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 with a pin and connect to an oscilloscope. If you need help using the oscilloscope see your 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 ……√…….
3.0 Watch and Record Oxygen Signal pattern at 2500 rpm. Let 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 next to the graph.
3.2 How high does the voltage go? 0.908 v
3.3 How low does the voltage go? 0.107 v
3.3 How low does the voltage go? 0.107 v
3.4 What is the average voltage? (Some oscilloscopes have functions that will calculate the average for you. If not, just guess.) 0.500 v
3.5 How many “Cross Counts” does the signal have in 10 seconds? (One cross count is when it goes from high to low, or from low to high.) List here: 14
3.6 If the signal is not cycling normally, describe what the signal does:
OK
if it wasn't ok it could be misfiring or it could also have injector problems.
4.1 Freeze your pattern and draw or photograph it onto the graph below: Note the voltage and time per division or scale next to the graph.
4.0 Watch and Record Oxygen Signal pattern at Idle rpm. Let 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. 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 next to the graph.
4.2 How high does the voltage go? 0.857 v
4.3 How low does the voltage go? 0.167 v
4.4 What is the average voltage? (Some oscilloscopes have functions that will calculate the average for you. If not, just guess.) 0.450 v
4.5 How many “Cross Counts” does the signal have in 10 seconds? (One cross count is when it goes from high to low, or from low to high.) List here: 6
4.6 If the signal is not cycling normally, describe what the signal does:
its cycling normally so there is nothing wrong with at all.
OK
5.0 Make this Oxygen Sensor go rich by accelerating once or twice. (The fuel system should normally make the system go rich when you do a sudden acceleration.) Push on the accelerator quickly but don’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? 0.859 v
5.3 If this signal is not going high normally, describe what the signal does:
OK
6.0 Make this Oxygen Sensor go lean by doing a sudden 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? 0.131 v
6.2 If this signal is not going low normally, describe what the signal does:
OK
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 to the graph.
4.3 How low does the voltage go? 0.167 v
4.4 What is the average voltage? (Some oscilloscopes have functions that will calculate the average for you. If not, just guess.) 0.450 v
4.5 How many “Cross Counts” does the signal have in 10 seconds? (One cross count is when it goes from high to low, or from low to high.) List here: 6
4.6 If the signal is not cycling normally, describe what the signal does:
its cycling normally so there is nothing wrong with at all.
OK
5.0 Make this Oxygen Sensor go rich by accelerating once or twice. (The fuel system should normally make the system go rich when you do a sudden acceleration.) Push on the accelerator quickly but don’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? 0.859 v
5.3 If this signal is not going high normally, describe what the signal does:
OK
6.0 Make this Oxygen Sensor go lean by doing a sudden 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? 0.131 v
6.2 If this signal is not going low normally, describe what the signal does:
OK
7.0 Measure the Response Time of the sensor. You want to know 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 to the 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: 100ms
8.0 Discuss how a normal Zirconium oxygen sensor works: draw a picture below to help show how it works?
Switching voltage. the voltage goes up and down and it doesnt stay normal
it shows which condition the car is running lean or rich if it goes up it means
that its rich and if it goes down its more leaner .
The zirconium dioxide, or zirconia, lambda sensor is based on a solid-state electrochemical fuel cell called the Nernst cell. Its two electrodes provide an output voltage corresponding to the quantity of oxygen in the exhaust relative to that in the atmosphere. An output voltage of 0.2 V (200 mV) DC represents a "lean mixture" of fuel and oxygen, where the amount of oxygen entering the cylinder is sufficient to fully oxidize the carbon monoxide(CO), produced in burning the air and fuel, into CO2. An output voltage of 0.8 V (800 mV) DC represents a "rich mixture", one which is high in unburned fuel and low in remaining oxygen. The ideal setpoint is approximately 0.45 V (450 mV) DC. This is where the quantities of air and fuel are in the optimum ratio, which is ~0.5% lean of the stoichiometricpoint, such that the exhaust output contains minimal carbon monoxide.
The voltage produced by the sensor is nonlinear with respect to oxygen concentration. The sensor is most sensitive near the stoichiometric point and less sensitive when either very lean or very rich.
9.0 Discuss how good or bad this Oxygen Sensor is. What about it functions well or is faulty? Use detail and specific voltages in your discussion. Can it accurately tell the ECU how rich or lean the exhaust is?
Over all the oxygen sensor was in good condition we didnt find anything wrong with it
i mean there was no faults or what so ever and this was also check by the teacher
to make sure we got it correct.
When I made a rich or lean suddely, sometimes, the voltage move out between 0.2 and 0.8voltage. but It is not normal and might be Okay. The signal is cycling normaly and average is 0.5V. It means the sensor send accurate signal to ECU and control the mixture well.
When I made a rich or lean suddely, sometimes, the voltage move out between 0.2 and 0.8voltage. but It is not normal and might be Okay. The signal is cycling normaly and average is 0.5V. It means the sensor send accurate signal to ECU and control the mixture well.
