APPT 5110 16/03/2011

Today i had my second class of COMM, Health and safety and problem solving. I learned what is required to pass this class. Half the marks are for a group presentation and a group portfolio. The other 40% is from two written assignments on various topics. The last %10 is for completing this blog every week after class. These requirements should be fairly easy.I started my group portfolio today on the topic what is the biggest problem in your industry. In my group is Haroon, Jono, Kevin and myself. We disused alot of problems for the automotive industry including lack of fuels, emission and safety problems and alternate fuels and energy's to run a car. My group works well together we generally agreed on what topics were do-able and which ones weren't. It was a good start for our group. We should work well for future group activity's.

OFF car wasnt showing up

Wasted Spark.

Coil primary
1= 0.7 Ohm
2=0.8 Ohms
3=0.6 Ohms

Coil secondary
1=12.2K ohms
2=12.3K ohms
3=12.3K ohms

Testing Ballast resistors
Part no: BR1
Resistance= 1.2 Ohms.

Standard Single tower coil




1. Wire up a ballast resistor in series with your coil primary winding values as shown in
the following diagram.
2. Connect an ammeter in series and note the current draw.
3. Measure and note the voltage drop across the ballast resistor.
4. Measure and note the voltage drop across the coil primary.

Current draw was 3.1A
Coil calculated voltage drop=6.51V
Coil measured voltage drop=10.6V
Ballast resistor calculated voltage drop=3.72
Ballast resistor measured voltage drop=1.3V

WS7 Exhaust Gas Analysis

In the AIR

CO: 0%
HC: 0 ppm
CO2: 0.033%
O2: 21%

Start the engine measure when engine is cold.
CO: 0.07%
HC: 129 ppm
CO2: 15.11 %
O2: 0.33%

With the engine warming up
CO: 0.5%
HC: 100 ppm
CO2: 14.3%
O2: 0.48%

With engine at 2500 rpm
CO: 0.01%
HC: 17ppm
CO2: 15.18%
O2: 0.38%

Run the engine rich with propane and measure the results
CO: .011%
HC: 5 ppm
CO2: 15.16%
O2: 0.08

Make a vacuum leak and record the engine while running lean
CO: .004%
HC: 10ppm
CO2: 14.57
O2: 1.12%

The Lambda value was 1.053

Record the readings when accelerating.
CO: 0.039%
HC: 6ppm
CO2: 14.8%
O2: 0.52%

We were unable to complete experiment as power died.

WS3B Dual Pattern

Using a dual trace (two channels A/B) oscilloscope capture the following
components and plot them against each other
The following sensors are used for WS3B:
MAP (analogue voltage) against Injectors (petrol)
RPM (Hall digital crank or distributor) against Injectors (petrol)
Oxygen sensor against Injectors (petrol)
Ignition primary against Injectors (petrol)
Ignition primary voltage against Ignition primary current

MAP (analogue voltage) against Injectors (petrol)

Signal Name: MAP Sensor vs Injectors

Volt/division: 10V

Time/division: 5ms


This waveform is comparing injector to the MAP sensor. This waveform was taken at idle so the MAP sensor voltage did not change. The injector waveform is normal. If more throttle is applied then there will be more voltage at the MAP sensor and the injectors will be opening and closing faster than at idle.If the MAP voltage did not change then the injection speed would not change so the engine wouldn't run at optimal performance.

RPM (Hall digital crank or distributor) against Injectors (petrol)

Signal Time: RPM Sensor vs Injectors

Volt/division: 10V

Time/division: 10ms

The injector is just the normal waveform with charging voltage, PWM time, Back EMF then back to charging voltage. The CKP sensor is fluctuating at idle producing AC voltage. As the CKP voltage increasing and the amplitude this means the engine is rotating faster. So the injectors will open and close quicker.

Oxygen sensor against Injectors (petrol)



We were unable to have the waveforms on the same screen because of the digital oscilloscope .The injector is just the normal waveform with charging voltage, PWM time, Back EMF then back to charging voltage. The oxygen sensor is fluctuating from rich to lean.

Ignition primary against Injectors (petrol)


We were unable to have the waveforms on the same screen because of the digital oscilloscope .The injector is just the normal waveform with charging voltage, PWM time, Back EMF then back to charging voltage. The beginning of the ignition waveform is charging voltage. The Voltage then drops to 0V by the ECU/ Igniter. Next a Back EMF is caused which is 40V. Which is when the spark is created. Next is spark duration and coil oscillations and back to charging voltage.

These two compare because when there is fuel being injected , you need a spark to complete combustion and create any form of power. As injectors spray quicker a spark needs to be created quicker. If there was no spark or injection the engine would not run. Unless it was just no spark or injection on 1 cylinder or 2 cylinders for some engines.

We were unable to get a waveform using current as it wasn't supported by the oscilloscope.

WS3 Ocilloscope Patterns

These sensors and actuators are used for the general lab worksheet WS3:
You need to capture at least 7 patterns from the lists below:
Sensors
MAP (digital)
MAF (digital)
TPS (switch type)
RPM (ac magnetic crank or distributor)
RPM (cam or distributor)
RPM (Hall digital crank or distributor)
Oxygen sensor
Actuators:
Injectors (petrol)
Injectors (diesel)
Idle air (digital 2 wire)
Idle air (digital 3 wire, both channels)
Ignition timing control (digital or analogue)
Ignition primary
Ground noise
Alternator ripple

Alternator Ripple

Signal Name: Alternator Ripple

Volt/division: 188mV

Time/division: 2.1ms

This above waveforms show the alternator ripple for idle and under load. With headlights , Air con, Radio ect on. The Alternator produces AC voltage and current . The battery requires DC voltage and current to charge properly. Diodes located within the alternator rectify the AC to DC. However, a small amount of AC can still be present and no harm is done. Problems can develop when alternator diode faults permit unacceptable amounts of AC to pass into the electrical systems.

Ignition Primary

Signal Name: Ignition Primary.

Volt/division: 20V

Time/division: 2ms


The beginning of the waveform is charging voltage. The Voltage then drops to 0V by the ECU/ Igniter. Next a Back EMF is caused which is 40V. Which is when the spark is created. Next is spark duration and coil oscillations and back to charging voltage.

Ground Circuit.

Signal Name: Ground Circuit

Volt/division: 0.5V

Time/division: 2ms

This shows a low amount of voltage in the earth circuit which in term means low resistance. Our voltage from the waveform was 0.006V which is very small. This is acceptable from the manufacturers specifications. Anything above 0.050V is considered excessive.

MAF sensor

Signal Name: MAF sensor

Volt/division: 2V

Time/division: 50ms

This waveform is showing MAF voltage when accelerator was pressed and released slowly to create this waveform. This shows as more air enters the engine there is a larger voltage produced.

MAP sensor

Signal Name: MAP Sensor

Volt/division: 2V

Time/division: 100ms

The beginning of this waveform was the MAP at idling voltage. When accelerator was pressed and released this waveform was created. This shows voltage is increased as more throttle is applied. The Map sensor produces a voltage created from the vacuum inside the intake manifold.The data 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. At the end of the waveform it is back to idling voltage.
Secondary ignition pattern

Signal Name: Secondary Ignition

Volts/division: 4KV

Time/division: 3.4ms

This waveform is from the secondary ignition off a b16A integra.

The ignition secondary picture shown above in the waveform is a typical picture from an engine fitted with electronic ignition. The waveform is an individual secondary High Tension (HT) picture that can be observed one cylinder at a time.

The secondary waveform shows the voltage required to jump the plug's electrode (A), and (B) the length of time that the HT is flowing across the spark plug's electrode after its initial voltage to jump the plug gap. This time is referred to as either the ‘burn time’ or the ‘spark duration’.

In the illustration shown, it can be seen that the horizontal voltage line in the centre of the oscilloscope (C) is at fairly constant voltage of approximately 3 kV. This voltage is referred to as the Sparkline kV. This voltage is the voltage required to maintain the spark flow across the plug's electrode, and is determined primarily by the secondary resistance within the HT circuit. From the 0 ms point on the scope to point D is the spark duration, in this case around 1.0 milliseconds. The waveform is then seen to drop sharply into what is referred to as the ‘coil oscillation’ (E). The coil oscillation should display a minimum number of peaks (both upper and lower) and at least of 4 - 5 peaks should be seen. A loss of peaks on this oscillation shows that the coil needs substituting. An example of a faulty coil and the subsequent loss of oscillations can be seen in Fig 1.2. The oscillation seen at point (F) is called the ‘polarity peak’; this voltage will be of the opposite polarity to the plug firing voltage as this is created when the magnetic flux is initially built, or at the start of the dwell period.

http://www.pc-oscilloscopes.com/primary-vs-secondary.html

Magnetic Distributor.

Signal Name: RPM (Magnetic, Distributor)

Volt/division: 10V

Time/division: 10ms


This is the voltage created at idle. As frequency increases so does voltage and amplitude. If the engine RPM was increased voltage and amplitude would also be increased. This is AC voltage.This works with a magnet and a pick up coil. As the air gap/ distance from the magnet gets further away voltage gets lower and when it gets closer voltage gets higher. The engine will die if the ECU does not receive this signal.

WS3A Ocilloscope Patterns

MAP Sensor

This waveform was taken during a sharp acceleration. The voltage increases when more throttle is applied. Where the waveform starts is point A that is idling voltage. where it increases is when more throttle is applied and the end on the waveform is idling voltage again.

A fault to stop the MAP sensor working could be a broken connection, it could be open circuit inside the MAP sensor. Could have excessive resistance in the wiring loom. There could be a wiring fault when it was connected.

MAF sensor



The beginning for the waveform point (A) is the MAF at idle. at point B when it is increasing this is when the throttle was applied and more air was allowed into the engine.At point C it would be back to idle voltage.An electrical fault could be the wire not heating up and resistance doesnt change so voltage would always be the same.In this situation the voltage would always be 1.7V and would not change. The effect of this would be the car would run in limp home mode and idle will fluctuate. The graph would look like a straight line with no movement from idle voltage.

TPS .



We didnt have a linear type so we used a potentiometer type. point A is 0.5V whcih is idle voltage. It slowly increases as more throttle is applied this is because resistance decreases as more throttle is applied. This is a variable resistor. The problem could be excessive resistance in the earth wire. So there would be less voltage at the TPS. So the ECU would not know how much the throttle was applied. So the engine would run rich.

ECT

This graph shows what happens to the ECT. It would be difficult to get a waveform showing the voltage changing. The ECT is a NTC thermistor. This means as temprature increasing resitance decreases. A problem again could be excessive resistance so the ECU would not recieve the correct voltage and would not know if the engine is hot or cold. If the ECT voltage didnt change stayed at 5V the engine would be constantly rich.

IAT



This graph shows that the IAT is NTC thermistor. resistance decreases with TEmprature. It would be difficult to get a waveform showing the voltage changing. Again the problem could be excessive ressistance within the circuit. This would mean the ECU would get incorrect signal voltage. This is how the ECU knows it is a cold start by comparing voltage to the ECT. if there was excessive ressitance the voltage would be lower.

WS5 Scan Tool Diagnostics

Scan Tool readings.

Engine Load MAP 0.9 V
Engine RPM RPM 750 RPM
Throttle angle TPS 9 percent
Engine coolant ECT 85 Degrees celcious
Intake air temperature IAT 56 Degrees celcious
Fuel Injection opening pulse PWM 1.5 MS
Vehicle Speed VSS 0 KM/H
Oxygen sensor(s) 02 0.8V
Idle control IACV 265 mA

There were no faults as the car has no problems.

Create Faults

3 MAP Voltage to high

6 ECT Voltage to high

7 TPS Voltage to low.

The problem was the MAP,ECT and TPS were all unplugged.

To repair I plugged the connectors back in.

Recheck

ECT 85 Degrees

MAP 0.9V

TPS 9 %

To clear the codes i disconnected the battery.

There where no error codes after disconnecting the battery.

Live data is usefull for finding intermitant faults.

Scan tool aids fault finding because it will tell you which sensor / circuit has a problem then you can diagnose it yourself. It saves checking multiple things just have to check the one with a problem.