4826 off car

TPS Sensor Type 

This is a Throttle Position Sensor which has four pins rather than 3 pins like on the Switch type Throttle Position Sensor. Vcc  pin which is the supply voltage, VTA (Voltage Throttle Angle) pin which is an output to the ECU. Also an IDL (Idle) pin which is a switch that only closed at idle and a E2 pin which is earth.

The TPS sensor type works by having a 5 volt input, coming through Vcc and out to earth. Depending on where the throttle butterfly is eg. idle, cruise or full throttle, the output voltage at pin (VTA) will change. At idle there will be low voltage, telling the ECU that little fuel is needed because there is less air coming into the engine. At full throttle the there will be high voltage, telling the ECU to more fuel in because there is more air coming into the engine. It changes the voltage with a potentiometer, so when the throttle butterfly moves open or closed the potentiometer varies its voltage. When i tested it, the voltage read 0.424 volts at idle and 3.89 volts at wide open throttle.

TPS Switch Type

A TPS Switch type has 3 wires, PSW (Power Switch), E  (Earth) and IDL (Idle circuit).  Unlike the TPS Sensor type, it measures signal voltage at idle and wide open throttle (WOT), not in between. 

Manifold Absolute Pressure 

A Map Sensor also called a vacuum sensor measures the amount of vacuum pressure in the intake manifold, .  This helps the ECU calculate the correct amount of fuel to inject into the engine (Air/Flow Mixture). How it works is inside of the sensor is a silicon chip, that is effected by air pressure or vacuum.  As vacuum increases resistance also increases and vice versa. The map senor i tested was within manufacture specifications.

Mass Air Flow Sensor 

The Mass Air Flow sensor (MAF) measures the amount of air coming into the intake manifold. As air passes the NTC (negative Temperature coefficient) it cools which reduces the resistance, this heats up the PTC and sends the signal to the ECU. When i tested the MAF sensor i got a reading of 1.1 volts, this is with no air passing through. When air passed through, the voltage went up to around 4.5 volts. This is within manufactures specifications.

Vane Air Flow Sensor

A vane, or paddle, projects into the engine’s intake air stream on a spring-loaded arm. The vane moves in proportion to the airflow, and a voltage is generated in proportion to the distance the vane moves, or the movement of the vane directly regulates the amount of fuel injected.

Thermistor 

I tested a NTC thermistor, as the temperature rises  the resistance of the wire inside lowers sending a signal back to the ECU. 

Fan Switch

As the heat changes in the fan switch, the resistance gos up or down depending on temperature. When i tested the fan switch by heating it up in a bowl of water the resistance increased as the water got hotter. When the temperature got to 90 degrees celsius the fan swicth turned on, (the resistance went to OL on Ohmmeter)     

Knock Sensor 

When the crystals inside of the sensor are knocked, its creates an AC voltage which can be seen very nicely on the oscilloscope. In the picture below there are two knocks, a smaller knock followed by a bigger knock.

Inductive, Hall, Optical Distributer

Hall uses a chopper plate to block the magnetic field to the hall chip, this turns it on and off. Optical does the same thing but blocks the light between 2 diodes. Inductive uses a magnet to pass windings to induce a current, this is similar to hall effect.

Each degree turned will be on or of. If there is 360 angles of switching, we can determine the position of the crack.

Testing Ignition Coils 

Coil Specs - CIC31

Voltage      - 12V

Primary      - 3 to 4 Ohms

Secondary  - 7.5 to 9 K Ohms     

Results 

Primary     - 3 Ohms

Secondary - 9.5 K Ohms

Wasted Spark Coil Pack

Primary      - 7.2 K Ohms

Secondary  - 7.2 K Ohms

Primary      - 1.2 Ohms

Secondary  - 1.2 Ohms

Measuring Current Draw and Voltage Drop

When i measured current draw and voltage drop over the circuit, which is a ballast resistor and coil pack in series, the measurements were almost the same as my calculations. I did a voltage drop over the wires and found found there was a higher voltage on the earth lead than there should have been. I replaced the wire with a better one and the readings were more accurate.