Ignition Coil 3.9 V8

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Originally Posted by BigJon

Thanks to everyone for their input.

I haven't yet checked to see if the balancer has spun, this Rangie is very much a fill in, in between type of job.

It does idle OK at the 12+ degrees of ignition advance, but only for a short while. Then it surges a little and dies. During the surging it won't react to the throttle (ie, it won't rev up and it will die, nothing can be done to prevent it).

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Fuel pressure, or lack therof can cause similar symptons, it out there, but always pays to eliminate, have you actually looked at the spark, with block out touching the block, is it strong?? If these come up trumps, its time to look at fault codes etc.

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Originally Posted by HangOver

so it looks like I'll be getting a ballast resistor before I drive it again.

I'm guessing that I fit the resistor on the + side of the coil between the ingnition unit and the coil?

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It's not as simple as that.

During cranking, the ballast resistor (or resistive wire) is bypassed so that the coil receives full battery voltage (which could be as low as 9 volts).

After the key is released, the ballast is switched back into circuit to reduce the voltage to 9 volts.

Note that the ballast resistor, in theory, has to be a specific value to suit the coil if it is to drop the battery voltage to the right value for the coil. In practice, it may not be too critical as there are a number of other vasriables, e.g. state of charge of the battery, battery voltage owing to age, alternator charge voltage/current, etc.

Ron (not a mechanic or auto elec)

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Originally Posted by p38arover

It's not as simple as that.

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now your just trying to confuse things ! :D

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Originally Posted by HangOver

now your just trying to confuse things ! :D

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I do my best.

Ron