Resister coil vs non resister coil

[larson24]

How does one determine if they have a resister or non resister coil if it is not written on the coil. I found out the hard way that my boat uses a resister after a shop sold me a non resister and it burned up. Thanks.

 

[Bondo]

Re: Resister coil vs non resister coil

Ayuh,.... What motor,..?? What drive,..?? What vintage,..??

 

[larson24]

Re: Resister coil vs non resister coil

This was a 99 5.0 volvo gl - pbyc, was sold a coil for external resister, and after 15 minutes or so running time, coil had too weak a spark to fire plugs.

 

[Don S]

Re: Resister coil vs non resister coil

I found out the hard way that my boat uses a resister after a shop sold me a non resister and it burned up. Thanks.

You have an electronic ignition (Prestolite BID ignition to be exact) you do not have a resistor wire or a ballast resistor. Nor is the coil built with an internal resistor.
Exactly what do you mean it burned up?
Have you considered getting the proper coil for your engine? The Volvo PN is 3852217. You can get aftermarket coils, just make sure the part number of your aftermarket coil crosses to the Volvo number.

 

[DonNZ]

Re: Resister coil vs non resister coil

Beg borrow or buy a ohm meter. Measure the resistance and compare it to your original coil.

Regards Don

 

[Mullin]

Re: Resister coil vs non resister coil

How does one determine if they have a resister or non resister coil if it is not written on the coil.

Measure the resistance between the positive and negative connections on the coil. An internally resisted coil should have 3 Ohms of resistance or more.

 

[Don S]

Re: Resister coil vs non resister coil

It doesn't really matter what your old coil measures, it doesn't work.
Here are the specs from the OEM service manual.

Operating Amperage @ 75? F ..................... 1.0 Maximum
Primary Resistance, in Ohms @ 75? F .......... 1.26 - 1.54
Secondary Resistance, in Ohms @ 75? F ...... 9400 - 1100

Coil must sustain 25-30 kv for 30 seconds

 

[DonNZ]

Re: Resister coil vs non resister coil

Why a resistor

The resistor is 99% externally wired as a down and dirty regulator that works quite well.
Usually either a white ceramic around the size of your favourite gum or it can be a special resistor wire in the loom.
It came about originally to allow a 6v coil to run on a 12 v system. If your older than 40 probably had a car that would fire once you let the key back from start.
This as a small improvement to starting by iincreasing the spark energy by automatically eliminating the resistor during cranking and also a small improvement at higher engine speeds.
The resistor was nessacary as the contacts / ignition points couldn't handle the extra current from running the 6 v coil on 12v, early electronic systems have also done this as a stop gap until electronic technology could handle the many times increase in current.

Sometimes a similar power resistor is used for more modern very powerful ignition systems to limit the maximum current, You probably have seen similar with some fuel injectors. This to contribute to very fast injector pintle accelleration.

Regards Don

 

[Don S]

Re: Resister coil vs non resister coil

Why a resistor ............................................

He does not have a resistor, or a resistor wire in his 1998 Volvo BID ignition system nor does it have a built in resistor in the coil.