Thread: Toasting Coils

............."Seems my ignition woes are being caused by the coil burning out"...

Without knowing what type of vehicle you have, I'll make a generic observation.

Older cars/4wd's have a 12 volt ignition system where the full battery voltage is applied to the coil whenever the ignition is turned on. This method (generally) was superseded in the early '70's with a setup where a resistor is wired in series with the coil so that the full 12 volts was not connected continuously to the coil when the ignition was turned on.

This (resistor/coil) setup allowed for full battery voltage to be connected to the coil when starting to give an improved spark. With the engine running the coil voltage is dropped to around 7 volts as the resistor reduces the operating voltage of the coil.

If you have an ignition coil designed for a resistor/coil setup and there is no resistor in circuit (or the resistor is short circuited) the coil will burn out as it is not designed to have 12 volts on it all the time.

This may be your problem.

Deano

Deano thanks for the reply. Vehicle is 1997 discovery so efi and coils being used are all for electronic ignition. As explained original coil was a bosch specifically for the d1 second was a fuel miser replacement third was a bosch transformer coil mec 723 even though advised not to use this style was out of options at the time. Next one was an original part number bosch and am currently running a second hand falcon unit.

I's why all of my electronic coil conversions use second hand coils from the wreckers. Australian made OEM coils from the 80's are tons more reliable than new "made in China" substitutes. Trouble is, the 80's are way back and wreckers tend to chuck stuff like that out. The D1 must have been one of the last vehicles on the planet to use oil filled single coils from new, everything now has one plastic coil per cylinder.

The Falcon coil should be fine but PM me if you want another second hand suitable coil, I have a few around at the moment.

Originally Posted by bee utey

I's why all of my electronic coil conversions use second hand coils from the wreckers. Australian made OEM coils from the 80's are tons more reliable than new "made in China" substitutes. Trouble is, the 80's are way back and wreckers tend to chuck stuff like that out. The D1 must have been one of the last vehicles on the planet to use oil filled single coils from new, everything now has one plastic coil per cylinder.

The Falcon coil should be fine but PM me if you want another second hand suitable coil, I have a few around at the moment.

You are an absolute legend bee utey. I may just do that for a back up. So you think it is just the build quality of the coils letting me down or another issue somewhere else?

MY sons XH ute had the same problems changed coil blew straight away.
Common problem on EFI fords. You need to change your ignition leads to good quality ones and your problem should go away.
I don't know how they cause the coil to fail. But it will do your head in trying to figure it out.
Mark

Originally Posted by DeanoH

............."Seems my ignition woes are being caused by the coil burning out"...

Without knowing what type of vehicle you have, I'll make a generic observation.

Older cars/4wd's have a 12 volt ignition system where the full battery voltage is applied to the coil whenever the ignition is turned on. This method (generally) was superseded in the early '70's with a setup where a resistor is wired in series with the coil so that the full 12 volts was not connected continuously to the coil when the ignition was turned on.

This (resistor/coil) setup allowed for full battery voltage to be connected to the coil when starting to give an improved spark. With the engine running the coil voltage is dropped to around 7 volts as the resistor reduces the operating voltage of the coil.

If you have an ignition coil designed for a resistor/coil setup and there is no resistor in circuit (or the resistor is short circuited) the coil will burn out as it is not designed to have 12 volts on it all the time.

This may be your problem.

Deano

I used a 6 volt coil on an EH Holden in Showroom Stock racing 1960's. EH's used a resistor so the standard coil normally ran on 9 volts and 12 volts in the starting circuit. The 6 volt coil gave a good bit more spark oomph and I can't recall ever burning one out even when used on a daily driver. One of the many little tricks used in Showroom Stock to make an EH149 with single Stromberg able to pull 6200 rpm down the straight at Lowood. No cheating at all, just the Smoky Yunick interpretation of the rule book.