Wednesday 25 May 2011

Testing Ignition Systems


this practical required me to test components of an igntion system on a car,namely Toyota Cynos 1993. I removed the high tension leads and the spark plugs off the car for analysis. I also had to check the distributor on its condition aswell as setting the timing and testing the vacuum advance.


As required i did all the pre-proceedure tests i.e checking the oil levels through the dipstick located in the engine, the coolant level, the fuel(fuel gauge ofcourse) and the battery condition.


Battery test: Unloaded:12.33Volts.... Cranking:1.05 Volts.... Recovery:12.39 Volts




I carried out a continuity test on the High Tension leads.On inspection, two of the High Tension leads to spark plugs 1 and 3 had faults. Lead 1 had no reading when i did a continuity test on the leads,indicating a short and lead 3's wire had worn out, so they needed replacement to ensure efficiency.  The other two passed with resistances of 15KΩ and 14KΩ. this is crucial as the  secondary side of the ignition system carries a very high voltage.
The distributor check revealed that the contact points in the distrubutor cap had worn out and this was causing bad contact that resulted in misfiring in the engine. The rotor's contact effectively had worn out so i got a new distributor cap and rotor as replacements to fix the problem.


The following video is of me testing the king lead with a spark connected to it directly and measured with a multimeter set to volts,obtaining a reading of 11.58V. this cleared as in good working condition

I then removed the spark plugs with from the cylinder to check the condition visually.it is important to remember to the order in which they came out for when re-fitting them back.By inspecting the condition and colour of the electrodes of the spark plug, the condition of the combustion burning can be determined








the above link is to a chart similar to the one i used to cross reference the spark plugs condition and they were in good working condition so i refitted them as i had taken them out.

Checking The Timing
with help from my class mate,i used a timing light to check the intial timing,looking at the T.D.C timing marks. the light is clamped to spark plug number 1 lead and the battery, while engine is running.It is pointed to the crank pully,as the firing of sparkplug 1 and the crankshaftpulley timing marks are related.Gradually increasing the engines R.P.M's until the timing marks advance from the intial timing mark,till it reaches its maximum advance and return it to normal idle.the number of degrees it moves from initial to maximum is the degree of mechanical advance.if the timing off,to adjust you loosen the distributor clamp so you are able to move it.Turning the distributor clockwise retards the spark; turning it counterclockwise advances the spark. then increase the R.P.M's again then watch the marks on the crankshaft with strobe light.The markin should advance,then turn the distributor to the spec maximum degree advance.return the engine to idle and then shut the engine off and tighten the distributor,the timing should be adjusted after this proceedure.



OFF CAR IGNITION

i measure six high tension cables for their length and their resistance.
33
56.5
57.5
67
82
94
Length in CM’s






12Kohms
13Kohms
14Kohms
15Kohms
15Kohms


15Kohms
Measured Resistance




No faults
No faults
No faults
No faults
No faults
No faults
Visual Inspection

p
p
p
p
p
p
Pass or Fail










Next was to check the ignition coils.below is the results for the two coils i measured.following that is the video of the coil circuit with a switch and another one with the distributor connected. the last video simulates the events in the ignition system on car as the distributor passes on the charge to the spark plugs.





Coil Specifications:

1st Coil Part Number …f-088 2nd Coil Part Number 16c6..

1st Coil Voltage …12V.……………….. 2nd Coil Voltage …6V….………………..

1st Coil Primary Ω ….……………….. 2nd Coil Primary Ω ….…1.4Ω …..

1st Coil Secondary Ω ……………….. 2nd Coil Secondary Ω ……7.54KΩ








off car i tested an ignition coil with a ballast resistor and high tension lead with a spark plug connected.
the spark of the plug would indicate the coil working.


i also tested the ballasts' resistance and it was 1.4 Ω

VACUUM ADVANCE TEST
 the following videos are of the vacuum test i did off car.




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