Note: POW means power switch (WOT)
IDL means idle circuit
IDL means idle circuit
E means earth
plot your findings on the graph
Throttle Valve Opening
Explain the internal operation of this sensor and why the resistance changes.
The TPS is usually mounted directly onto the throttle body measures the angle position of the throttle the resistance measures as the throttle opens because the styler is moving up the carbon strip measuring voltage.
Manifold Absolute Pressure (MAP)
Does the map sensor match the manufactures specifications why?
yes it does the lighter the vacuum the lower voltage or vice ureas
Does a map sensor read vacuum or pressure?
The map sensor is a key sensor because it senses engine load.The sensor generates a signal that is proportional to the amount of the vacuum in the intake manifold the engine computer then uses this information to adjust egnation timing and fuel enrichment.
Explain the internal operation of this sensor and why the output
voltage changes.
output generally changes about 0.7 to1.0 volts for every 5 inches MAP sensors voltage can also be read directly using and engine management system.
Air flow/mass sensors (MAF)
What voltage did you get when you first powered up the sensor without passing air over the sensor?
When i powered up the sensor without passing air over the sensor in that time the voltage was 1.03 volts.
How did the voltage change when air was passed over the sensor?
when the air was passed over the sensor the voltage is gone up from 1.03 volts to 3 volts. you can see from the picture above.
Are your results within the manufactures specifications, why or why not?
yes it is within the manufactures specification because it is 1.03 volts and specification is 3 volts
Explain the internal operation of this sensor?
Mass air flow sensor typically either send a voltage or frequency signal to the powertrain control module PCM. Hot wire sensors typically have an operating range of 0 to 5 volts with idle voltage being around .5 to .8 volts and full throttle application is normally between 4 and 5 volts.
Vane or flap air flow sensor/meter (AFM)
checking sensor operation.
VANE ANGLE | VOLTAGE OUT |
Closed | 0.51 v |
30 degrees | 1.4 v |
45 degrees | 1.8 v |
60 degrees | 2.70 v |
75 degrees | 3.14 v |
90 degrees | 3.58 v |
Are your results within the manufacturers specifications, why?
yes it matches manufacturers specifications.
vane angle: closed specification 1.6 volts _+ 0.5 volts
tested: 0.51 volts
at 90 degrees: spec 2 to 4 volts
test result: 3.58 volts
Explain its internal operation and why your voltage changes?
This sensor converts the air flow meter vane opening angle to a voltage and send it to ECU. This signal allows the ECU to determine the volume of air that is entering the engine.
CTS (coolant temperature sensor)
THw (Thermistor water)
ECT (engine coolant temperature)
Temperature Resistance
(deg C) ( ohms)
-10 7,000-12,000
20 2,000-3,000
50 700-1,000
80 200-400
85+ less than 200
THERMISTOR
WATER TEMPERATURE | RESISTANCE |
20 degrees Celsius | 2.2k ohms |
30 “ “ | 1.8k ohms |
35 “ “ | 1.5k ohms |
40 “ “ | 1.2k ohms |
50 “ “ | 0.8k ohms |
60 “ “ | 0.6k ohms |
70 “ “ | 0.4k ohms |
80 “ “ | 0.3k ohms |
85 “ “ | 0.3k ohms |
Does the sensor meet the manufacturers specifications, why?
yes it does meet the manufacturers specifications the resistance drops as the temperature increases for example it is clear from the graph at 20 degrees celsius the resistance is 2.2k ohms as the temperature increased the resistance is dropped. At 85 degrees celsius the resistance is 0.3k ohms
What type of thermistor is this?
coolant temperature sensor ( CTS)
Negative temperature coefficient (NTC)
Explain the internal operation of the sensor?
CTS thermistor that change resistance as temperature of cooland changes. The resistor is high when the engine is cold. As the engine is warmed up the internal resistance of the sensor drop untill it reaches a maximum valve when engine is normal operating.
Thermo fan switch
Does the fan switch meet the manufacturers specifications?
yes it is an open circuitswitch once it reaches to a certain degree ( temperatures) it closes and then starts to work.
Is this a thermistor?
No it is not, once the temperature increase to 90 degrees celsius it works (the fan works)
Explain the internal operation and why your resistance changes?
The higher the temp the lower the resistance. once the temperature gets so high the resistance drops because the switch is closed completing the circuit for the fan to operate.
ATS (Air temperature sensor)
THa (Thermostat air)
IAT (Intake air temperature)
TEMPERATURE | RESISTANCE |
20 degrees Celsius | 2.3 k |
30 degrees Celsius | 1.9 k |
40 degrees Celsius | 1.3 k |
50 degrees Celsius | 0.9 k |
60 degrees Celsius | 0.6 k |
70 degrees Celsius | 0.4 k |
Plot the resistance and temperature on the graph below
Does the sensor meet the manufactures specifications?
yes it does meet the manufactures sepicifications as the resistance drops and the temperature increases.
What type of thermistor is this?
Negative temperaturre coefficient (NTC)
What do you observe about your results of the air and coolant sensors?
The ECM needs to adjust a variety of system based on temperatures. The engine reach operating temperature and the temperature is accurately signal to ECM. For the proper amount of fuel to be injected the ECM must know correct engine temperature.
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