Firing Voltage 45V Burn Voltage 12V Burn Time 1.4ms Dwell time 4ms
This picture of the primary waveform is very important. It tells you many things. For example it can show you that one cylinder has a high resistance, by having a very high firing voltage. It can tell you other information such as the burn time. This will show you how long it takes to burn the fuel while its in the cylinder.
This video shows the engine doing a snap acceleration. The oscilliscope is measuring the secondary pattern. Using a spark tester on the 1st cylinder I increased the gap so that it would require more voltage to jump the gap. As you can see in the picture, the voltage went off the chart. This shows you that the slightest resistance in any wire will ultimately effect your ignition in the cylinder.
With the gas analyser sensing normal air, the gas readings are C0 0.001% HC 15 Co2 0.01% 02 21.23% These readings show the air around us, without much contamination.
With the engine idling while cold you get these readings: CO 1.038 HC 156 Co2 14.42 O2 0.82% As the catalytic converter has not warmed up yet, the car is emitting a lot of CO.
3.The engine has warmed up now and the readings are:
CO.727
HC181
CO213.49
O21.9
This shows that the catalytic converter has started to work to reduce emissions.
4. The engine is warmed up and running at 2500 RPM the readings are:
CO5.5
HC419
CO211.14
O20.29
As the engine is at a faster speed, it obviously must produce more emissions.
5. At idle with a richened fuel/air mix the readings are:
CO.707
HC100
CO214.08
O20.45
I don’t think I made the mixture rich enough as the readings were the same as the engine warmed up.
6. At idle with a lean mixture the readings are:
CO0.129
HC66
CO2 13.92
O22.54
As there is an air leak, the O2 reading is high.
7. Under acceleration the readings are:
CO.676
HC198
CO28.03
O2.192
As the mixture gets richer with acceleration, the CO reading will get higher.
8. Disconnected spark plug wire grounded by a jumper wire, and the readings are:
CO2.3
HC3978
CO29.06
O28.27
As one cylinder is not having its fuel/air mix burnt all the readings will skyrocket.
Disconnected one injector, the readings are:
CO 737
HC 270
CO28.82
O28.6
Showing that the injector is open, as there is more fuel being unburnt.
The readings on a car without a catalytic converter would show that there is an excessive amount of CO,HC and CO2 that is being put into the atmosphere. As the ‘cc’s job is to reduce these emissions.
A car with a cc would have far less emissions once the cc has warmed up to operating temperature. The cc then converts CO and HC into CO2 and H2o.
I put this scan tool onto my Mzada capella 98. I used the correct plug and put it into the diagnosis plug on the car.
I got these readings off the cars live data. There were no fault codes. I unplugged some sensors and rediagnosed the car. There was three fault codes now. p0100 MAF sensor malfunction P0100 IAT Circuit malfunction P0505 Idle control system Malfunction
The IAT was the one we noticed still gave us a reading, even though it was unplugged. The ECU obviously has a preset IAT reading if the IAT is not working, in this case it was at 19*C. The MAF gave me no reading at all, and the Idle control circuit just stayed off.
I repaired the faults and all the fault codes were cleared via the scan tool. I then rediagnosed the car and no fault codes came up.
Live data is a great way of fault finding, as it is 'live'. So you can see the problem first hand. This can save a lot of time when working in a workshop.
The fire extinguishers can be found in the corner of the class. The fuel pressure spec on the toyota A4-fe is 265-304KPa.
To install the pressure gauge, you must relieve the pressure in the system first. You can do this by removing the fuel pump fuse and then cranking the engine. The gauge was properly installed and there was no fuel leaks. The gauge read 200 KPa. At idle the gauge read 25o KPa. Maximum pressure of 400 KPa. WOT of 300KPa. The Residual pressure was 250KPa. The flow is 2.2L per min.
I then uninstalled the gauge. I refitted the hoses, double checked them. I cranked the engine to check for leaks before starting it. It ran fine. It is important to know how the fuel system works, as it can help to find leakages and/or blockages.
Symptoms of a vehicle with these problems: Low fuel pressure: It would be unable to idle.
Low fuel flow: The car would run lean as there is not enough fuel being injected.
High fuel pressure: The car would run rich as the injectors would be forced to stay open longer than necesscary.
Faulty fuel regulator: Car would be jerking, or just not run at all as it starves for fuel.
We created 3 fault codes on the toyota 4a-fe engine. To make the flash codes come up on the dash, you must use a jumper wire across terminals TE1 and E1 in the diagnosis plug. The flash codes came up as 12, 22, 31 and 41.
12 was G-NE signal circuit which we found to be the distributor clearance was to big. This was a real fault on the engine. 22 was the ECT unplugged. 31 was the MAP unplugged. 41 was the TPS unplugged.
To clear these codes, we disconnected the negative terminal on the battery. On a new car this would not be acceptable, you would have to remove the appropriate fuse.
We rechecked the codes, and got a constant flashing light. This means everything is ok.
As we unplugged some critical sensors, the ECU would've have insufficient information to run the car at its optimum.
When everything is returned to its original place, turn the engine on and rev it to double check all is ok.
Back probing is used to test electrical circuits without disconnecting or damaging terminals. You can do this by inserting a pin down the wire at the terminal to get a reading. Using a multimeter set to ohms you must touch the ohm meter together to get the ohmmeter resistance, which was 2 ohms. I measured a wire by back-probing at each terminal. I got a reading of 2.5 ohms. I then minus the 2 ohms, to get the wires resistance of 0.5 ohms.
This shows that I had connectivity by back-probing as I didn't get an infinite reading.
The air flap is connected to a potentiometre which then effects the output volatage as the air flow changes. This Vane Flow Sensor does not meet specifications. I think there is extra resistance in the potentiometer as at idle the voltage does not even reach 4V.
Firing Voltage 45V
Using a spark tester on the 1st cylinder I increased the gap so that it would require more voltage to jump the gap. As you can see in the picture, the voltage went off the chart. This shows you that the slightest resistance in any wire will ultimately effect your ignition in the cylinder.
