I wonder if anyone can give me a bit of advice please?
I have a 1990 8v GTi and there's an intermittent fault with the ignition.Every so often when you try to start the car there will be no power getting to the coil,if you feed a live straight from the battery to the coil the car starts up fine then after running for brief period you remove the wire and the car works fine for a while,then without warning,you come to start it again another time and it just sits there turning over but no life at the coil again.
Any advice would be gratefully appreciated.
Many thanks.....Jon
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Is it old enough to have "conventional" ignition, fitted with a ballast resistor? Use to supply 7-9 volts the the coil when running, but 12v while the starter was cranked?
Not sure about VW, but didn't some Fords use a section of resistor wire instead of a discrete resistor
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No it's got electronic ignition and the digifant fuel injection system but thanks anyway Dave.
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I don't know the car, but if it has a single ignition coil, plus distributer, it seems to me you will have already done the main part of diagnoses. The electronics will most likely (to me) be to the other side of the coil, not the one you are puttng the lead on, as a sort of electronic equivalent of the contact breaker.
Be that as it may, somewhere the feed wire to the coil has an intermittent connection. The problem is to trace the wire going back towards the battery far enough to get back past the break. Then bridge or mend the break. Of course, if it is a switch contact problem, that will have to be repaired or replaced.
You don't really need a test meter for diagnosing this job. In fact test meters can be too sensitive so as to lead to error readings. I would rather use a pair of long leads connected to a 12 volt 5 watt or so bulb. Take one lead to the car body metalwork and the other then becomes a test lead. Thus if you clip that lead on the coil (where your battery lead works) it should light when the car is working and go out when not. Also go out when the ignition is turned off. You can even keep the bulb in the cab, if you wish, so that you can watch it. But be careful, once the lead is connected, not to catch the live lead or live side of the bulb on the bodywork as that constitutes a short on the battery.
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