Sensor testing part 1

Sensor testing

Crank Sensor

The crank-angle sensor is located in the distributor. It detects both engine rpm and crank angle, which is the angular position of the crankshaft. With the way it is arranged a perforated disc is used, together with a light-emitting diode (LED) as a light source and photodiode as a light sensor.

                        

The dis is rotated between the diodes, and light from the LED passes through the holes in the disc onto the photodiode which acts as a light sensor. The frequency of the light passing through the holes in the disc is used as a means of sensing speed. It can also be used to sense the angular position of the disc.

Testing

We tested the crank sensor with a Multimeter set on Ac voltz, we placed the first probe on the crank and the negative probe on a good earth. We tested it under two conditions: The first condition was at Idle RPM and we got a reading of 0.80v which is a good reading for this condition. The second condition was at 2500 RPM, the reading I got was 1.57v which is a good reading for the specified condition.

MAP Sensor

The manifold absolute pressure sensor measures the absolute pressure in the intake manifold; it is also referred to as manifold vacuum. The sensor is responsive to manifold vacuum and also to barometric pressure. The air/fuel ratio, the ignition timing and the idle speed can all be modified by the control unit as a result of the MAP sensor.

Testing

With a multimeter we connected the probes output connection on the circuit bourd and the earth to a good ground. We tested the first reading at idle vacuum which read 1.10v, this is a good reading because all air pressure is drawn out at idle. The next reading was at key on engine off condition the reading was 3.73v, this is a good reading because at no vacuum manifold pressure is full.

Coolant Temperature Sensor

The coolant temperature sensor is fitted into the water jackets of the engine. It senses coolant temperature and signals this to the control unit, which can adjust the fuel mixture and ignition to suit a hot or cold engine.

Testing

We connected the positive probe to the THW connection and the earth probe to a good ground, the first condition is with the engine cold and the second condition is with the engine warmed up.  The reading we got when the engine was running cold was 3.50v and the second reading we got with engine warm was 1.8v voltz.