blog one off car

THROTTLE POSITION SENSOR

There is two types of tps sensors known as the potentiometer and switching type

first type i tested was the potentiometer:
this can also be caled a veriaing type or linere type.
It is a three terminal resistor the wiper movin part is usaly the midle terminal of the three.
I got this from wikipedia.org

I conected a power supply to the sensor and tested the voltage at different throttle angles
and got a result of:

throttle angle:                                                            voltage output
0                                                                                     336mv
25                                                                                     0.9v
45                                                                                      1.6v
60                                                                                      2.5v
75                                                                                      3.2v
90                                                                                      3.89v

all angle is in degrees and the voltage output readings is for main if it was for the idle it would of been 100mv at all the angles.

The picture above is of potentiometer

Next I tested the switching type
is either on or of unlike the potentiometer
it switches at 15degrees to O.L no continuity
It switches at 75degrees from O.L to 0.55v
This is at wide open throttle

Air flow/mass sensors(MAF)
Hot wire type
I measured voltage when i first powerd up the sensor without passing air over sensor
got result of 0.32v
when i pased air over it I got a result of 2.6v
This result was within manufacturer specs

Next was the vane type
Hooked up to a power supply and recorded the voltage change with the differint angles:

vane angle                                                  voltage out
0%                                                                0.84v
25%                                                              2.14v
45%                                                              3.40v
65%                                                              4.40v
85%                                                              5.20v
100%                                                            5.80v

I checked the part number used google typed it in and it came up with all the specs and I found it was within manufacturer specs

The mass airflow sensor converts the amount of air drawn into engine into a voltage signal.The vane airflow meter provides the ECM with an accurate mesurement of load placed on engine.
vane type consist of the following:

• measuring plate
• compensation plate
• return spring
• potentiometer
• bypass air passage
• idle adjusting screw
• fuel pump switch

        intake air temp sensor
got this info from http://www.autoshop101.com/forms/h34.pdf
If any of these components are broken or faulty the air flow meter wont be able to work as it should.


Thermistor:
i took a bole filled with water then put thermister in on piece of wire and heated water up and recorded recistance as water heats up.

WATER TEMPERATURE                                                    RESISTANCE
35                                                                                           1.53kohm
40                                                                                           1.46kohm
45                                                                                           1.02kohm
50                                                                                           0.89kohm
60                                                                                           0.70kohm
70                                                                                           0.52kohm
75                                                                                           0.41kohm
80                                                                                           0.34kohm

All the temperature was measure in degrees.A thermistor is a type of resitor and resistance changes alot with the change of temperature.As temp goes up the resistance goes down.This makes it a negative tempreture coefficent,If the resistance would of increased with the temprerature increasin it woud be called positive temprerature coefficent.

KNOCK SENSOR:

I conected a knock sensor to an oscolloscope and tapped the end to get a waveform

time was on 830.0us and voltage on 1200mv
The knock sensor has a crystal in it that when it gets tapped it jumps around and creates a voltage therefor wee do not need to ad a voltage supply to it.In this photo the middel is called the 0 line.I had some trouble to get the setting on the osciliscope right but with the tutors help i got it perfectly right and the photo shows the outcome i got.