Off-CarPractical 2
Building a simplified ignition module
What difficulties did you encounter in building this circuit?
Finding the lowest possiblerange around 4.5ohms so the trigger can provide the current strongly to keep the circuit work and create good sparks in the secondary.
If you were going to build this circuit again what would you do differently?
It is necessary if this circuit can operate normally without resistors used and that depend on the type of trigger. One thing I would change is the resistance in the circuit. Goodadvance of the resistorcan create good sparks.
Sensors
TPS Throttle Position Sensor (potentiometer)
(It is critical that you follow the manufacturer’s set-up procedure) For example:
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.
Checking the Throttle Position Sensor
What type of TPS is this?
Potentiometer type sensors
Internal operation and why your voltage changes
At closed throttle the IDLE contact is held closed. This pull the IDLE signal circuit to ground, as the throttle open the IDLE contact break causing the digital IDLE signal voltage to go from low to high.
The operation is when the throttle is closed the full resistance value of the potentiometer is in series with the ECU reference voltage. This causes a large drop in the computer reference voltage and a low voltage signal is given. At wide open throttle, only a small amount of potentiometer resistance is in series with the ECU reference voltage, which causes only a small drop in the computer reference voltage so a higher signal is given to the ECU. Between these extremes of closed throttle and wide open throttle the magnitude of the voltage signal to the ECU will be proportional to the throttle valve angle.
The ECU, by monitoring the TPS voltage signals, can determine the fuel delivery required from the throttle valve angle.
NOTE: Always use a 5V supply
Throttle angle(In Degree) | Voltage output |
0c | 0.322v |
22.5c | 1.13v |
45c | 1.45v |
65.5c | 2.613v |
90c | 3.651v |
|
|
Graph
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. Note there is no switching at part throttle.
Throttle position switch detects throttle position at idle or full throttle by using switch contacts that are connected or disconnected as throttle position changes.
This type of switch can have two or three contact positions and is usually checked and adjusted using a multi-meter. Adjustment is made by loosening the mounting screws and rotating the switch assembly.
On - Off type throttle position switches can have:
Two position (three pin) or
Three position (four pin).
Testing the throttle position switch
,
PSW means power switch (WOT)
- IDL means idle circuit
- E means earth
Explain the internal operation of this sensor and why the resistance changes
As the IDE pass 1.5 degrees the IDE switch open this makes an open circuit at the IDE and when it gets to about 70 degrees it make the contact closed. This causes the change in the resistance.
Operation: In the voltage, the IDL signal voltage is high when the throttle is closed and goes low when the throttle exceeds about 1.5 degrees opening. PSW voltage is low until the throttle exceeds about a 70 degrees opening, then it goes high.
MAP (Manifold Absolute Pressure)
On this graph i recorded different voltage readings according to different vacuum. It shows that the MAP sensor load line is straight and for every vacuum reading its a specified voltage
Inspection Power Output of Vacuum Sensor
Applied Vacuum | 13.3 kPa 100 mmHg 3.94 in.Hg | 26.7 kPa 200 mmHg 7.87 in.Hg | 40 kPa 300 mmHg 11.81 in.Hg | 53.5 kPa 400 mmHg 15.75 in.Hg | 66.7 kPa 500 mmHg 19.69 in.Hg |
Voltage Drop |
0.3 – 0.5 |
0.7 – 0.9 |
1.1 – 1.3 |
1.5 – 1.7 |
1.9 – 2.1 |
| Vacuum Gauge | Voltage |
0 | 4.50v |
10 | 3.40v |
20 | 2.60v |
30 | 2.26v |
40 | 2.00v |
50 | 1.60v |
60 | 0.60v |
Graph
In this exacise the Vacuum's performance match the spec shows aboved.
Does a map sensor read vacuum or pressure?
Vacuum
Explain the internal operation of this sensor and why the output voltage changes
The test is react to the vacuum gauge as it induces the voltage decrease showing in the graph above. What happen is the map sensor measures the intake air volume by monitoring changes in the gauge this is the load,inside of the sensor is the silicon chip, when pressure in the intake manifold changes, the silicon chip flexes, causing a change in its resistance. With varying resistance of the sensor causes a change in signal voltage at the Pressure intake manifold terminal.
MAF Air flow/mass sensors
S4/SB/RS4 MAF Mapping
What voltage did you get when you first powered up the sensor without passing air over the sensor 5volts.
How did the voltage change when air was passed over the sensor?
When air passes through the air flow meter, it forces the measuring plate open and the volume of air entering the engine increases, the movable contact moves across the fixed resistor, causing a change in signal output voltage and gave the signal information back to the ECU. This signal voltage is now changing depends on the volume of air entering.
Operation
As the intake air passes through the sensor, the angle of the air flap will change according to the volume and velocity of the intake air demanded by the engine. The value of the potentiometer resistance that is sensed by the electronic control unit will be in proportion to the angle of the air flap.
A Mass airflow normally uses an energised resistance wire to detect airflow
Vane or flap air flow sensor/meter (AFM)
VANE ANGLE (In Degree) | VOLTAGE |
0c (close angle) | 2.270v |
22.5c | 4.50v |
45c | 7.80v |
65.5c | 8.50v |
90c | 9.30v |
Internal operation
The operation is reacting to the measuring plate. The voltage increases as the plate open. This cause by the resistor R2 connected in parallel with R1 allows the meter to continue to provide volts supply signal in the event that an open occur in the main potentiometer R1.
