Off Car

Throttle Position Sensor (potentiometer)

A throttle position sensor (TPS) is  used to monitor the position of the throttle inside the engine. The sensor is  located on the butterfly spindle so that it can directly monitor the position of the throttle valve butterfly and can move.
A potentiometer provides a variable resistance depending on the position of the valve.

Potentiometer type sensors are composed of variable resistors that have a slide contact

which changes its position as the throttle butterfly moves.

A voltage is supplied to the sensor by the ECU. As the throttle position changes, the

output voltage from the sensor changes, this in turn is recognised and a comparison made

by the ECU to its memory. These sensors are adjusted by loosening the sensor mounting

screws.

The idle position is recognised by the lowest voltage reading through the sensor but in

contrast, the maximum power signal is recognised by the highest reading at the full throttle

position of the sensor travel. It is important that both signals are correct.

 

Throttle Position Switch

There is an idle position signal that is used mainly for fuel cut-off control and ignition timing corrections. The power signal is created at full throttle and is used for increasing fuel injection volume which in turn increases engine power output.

 

What type of TPS is this?

We had a switch type TPS
Explain its internal operation and why your voltage changes

At idle the ECU knows that the  throttle is closed with certain resistance, when we accelerate and open the throttle fully  the ECU knows that the  throttle is open with certain resistance and the earth touchs PSW.When we leave the throttle to close the earth connects to IDL  

    

On the left Full Throttle , the middle is the voltage in and on the right is idle position



Manifold Absolute Pressure (MAP)

The Manifold Absolute Pressure sensor (MAP sensor) is one of the sensors used inside an internal combustion engine's electronic control system. Most Engines that use a MAP sensor are usaully fuel injected. The manifold absolute pressure sensor provides instantaneous manifold pressure information to the engine's electronic control unit (ECU). The data then is used to calculate air density and determine the engine's air mass flow rate, which in turn determines the required fuel metering for optimum combustion

We Wired up a map sensor (manifold absolute pressure) with a 5 V feed and earth. We Measured

the return voltage from the third wire.

Using a mity-vac apply vacuum to the map sensor.

Does the map sensor match the manufactures specifications, why or why not?Yes , because there were no faults found and the readings were within the specifications . If we did have a fault it would show on our graph, also the engine will idle rough and have problems accelerating 
Does a map sensor read vacuum or pressure?
Vacuum
Explain the internal operation of this sensor
The map sensor sends the ECU information about how much of intake air is coming in (manifold pressure), then the ECU controls fuel injection and ignition timing.                             
    
                               Vane or flap air flow sensor/meter (AFM)   
                          Air flow/mass sensors (MAF)

A Mass Air Flow sensor measures the amount of air coming inside the engine ,It is located  in the intake system, between the air filter and the throttle body of the car also it works on a DC (Direct Current).

2.8v

Explain the internal operation of this sensor

The MAF sensor sends out a voltage signal to the ECU depending on the amount of air coming inside the engine , the ECU then uses this information to calculate the engine load. This is important because it needs to determine how much fuel needs to be injected.

The Mass Airflow sensor is used to measure the amount of air going inside the engine by the hinged Flap. It sends out a signal to the  ECU of how much load is  placed on the engine by measuring the air intake volume. The hinged flab is connected to a potentiometer, the incoming air moves the flap and this moves the contact along the potentiometer. The different resistance is converted into a signal voltage and then sent to the ECU   

  

Closed: 2992 ohms

        Half: 2775 ohms   

                              Open: 3110 ohms           

  

Thermistor

Thermistors are temperature sensitive resistors, all the resistors vary with temperature, but thermistors are constructed of semiconductor material .A Thermistor is a temperature dependent resistor.  When temperature changes, the resistance of the thermistor changes . As the temperature of the sensor rises up, the voltage signal that it puts out decreases.

Testing the thermistor

                                                                   Knock Sensor

A knock sensor allows the engine to run with the ignition timing . The ECU will continue to advance the timing until the knock sensor detects pinging. At that point the computer retards the ignition timing just enough for the pinging to stop.

A knock sensor assures that you're getting as much power and fuel economy as is possible from your engine.

The knock sensor responds to spark knock caused by Pre-detonation of the Air/Fuel mixture. As the flame front moves out from the spark plug ignition point, pressure waves in the chamber crash into the piston or cylinder walls resulting in a sound known as a knock or ping. This is caused by using a fuel with a low octane rating, overheating, or over advanced timing

 http://wiki.answers.com/Q/What_does_a_knock_sensor_do#ixzz1YGsYyLfW

Knock Sensor we tested

Add caption

                                          Distrubutors
A distributor is a device in the ignition system of an internal combustion engine that routes high voltage from the ignition coil to the spark plugs in the correct firing order.

                                        Hall effect Sensor
The Hall effect sensor is a transducer that varies it's output voltage in response to a magnetic field. Hall sensors are used for proximity switching, positioning, speed detection.

                                              Injectors
Fuel injecters are used for mixing fuel with air inside the engine. It has become the primary fuel delivery system used in petrol engines, it has replaced carburetors . The Injectors spray the fuel inside the engine

Coils

A coil is a series of loops .

Testing ignition coils

Method

1 Obtain two different ignition coil configurations.

2 List all coil part numbers, voltage, internal resistance specifications where shown.

Coil Specifications

Coil#

Coil#  1

Coil# 1

Primary 1.3   Coil #2 Primary 1.5 Voltage 12v  Coil# 2 Voltage 12vCoil # 1
 Always check for meter error and deduct that value off your final reading

( most important when using the 0 - 200 ohm scale )

3. Obtain a multimeter.

4. Carry out tests and record your findings.

5. Turn the meter rotary switch to the 200 ohm position, touch the positive and negative

leads together and note your default error.

6. Carry out tests and record your findings

Coil Test Results

Coil #
Coil #1
Coil #1

Coil #2

Coil #2 Earth leakage test O.L

Spark Plugs on the right , Wasted Spark in the middle and on the left is a coil.

  

Wasted Spark Coil Pack

                                                               

Note: That if the coil you are testing is off a four cylinder engine you will only can check two secondary windings, also if the ignition module is incorporated within the coil you will not be able to test the primary windings

Coil 
Coil #2 Secondary 7000

Coil #1Primary 0.8

Coil #2 Primary 0.8

                                            Ballast Resistor

The ballast resistor Is an electrical resistor that is diverted into and out of the supply voltage to the ignition coil system. This ballast resistor actually lowers voltage after the engine is started to reduce or minimize wear on ignition components. It also helps the engine to fire much easier by effectively doubling the voltage provided to the ignition coil when the engine is being cranked. Not all car manufacturers used a ballast resistor in their ignition systems.
The ballast resistor is a resistance wire which is inserted in series in the primary circuit between the ignition switch and the positive terminal of the ignition coil.

Testing Ballast resistors

We Obtained 2 ballast resistors with different part numbers

Measured Resistance Values

Ballast resistor

No1 measured ohms 1.7 ohms Ballast resistor No 2 measured ohms 2.1 ohms

Measuring Current Draw and Voltage Drop

Standard Single tower coil

We Wired up a ballast resistor in series with our coil primary winding values as shown in the following diagram.

2. We Connected an ammeter in series and noted the current draw.

3.Next we Measure and note the voltage drop across the ballast resistor.

4. Measure and note the voltage drop across the coil primary.

Current draw 2.44amps
Coil calculated Voltage Drop V=IxR  V=2.44x3.2 = 7.808v
Coil measured Voltage Drop 7.88vd
Ballast resistor calculated voltage drop V=2.44x1.9=4.636v
Ballast resistor measured voltage drop 4.27v

This video shows the ignition system i wired up. We had 12v power supply going to the ballast resistor then to the coil which went to the spark plug and 12v to the positive on the ignition moddle , and the trigger wired to signal.


We Wired up an ignition module using a function generator to trigger the module.
and had a coil and spark plug in the circuit so the spark plug can fire.



I Wired up an ignition module using a distributor to trigger the module.

We Have used a coil and spark plug in the circuit so the spark plug can fire





We Wired up the coil over ignition system using the function generator to trigger the module

and used the coil and spark plug in the circuit so the spark plug can fire



Coil On Plug

Below is a video of the coil on plugs we wired up

Referance :

http://moodle.student.cnwl.ac.uk/moodledata_shared/cdx%20etextbook/dswmedia/electrical/ignition/conBreakComp/ballastresistor.html

http://www.google.com/

Wikipedia

Moodle / Work Books 

#1 Secondary 7050 ohmsPrimary 1.5 Earth leakage test 0.LSecondary 9300Coil #2 Secondary 14.49k

1 Primary 1.3 Secondary 8.5  Coil #2 Secondary 9.5

Remember

1 No CIT-118  Coil #2 No CB12500

What voltage did you get when you first powered up the sensor without passing air over the sensor?

0.32v , No air flow

How did the voltage change when air was passed over the sensor?