[Diy_efi] Bosch ignition coil

Rick McLeod dunvegan
Fri Mar 24 01:47:48 UTC 2006

This sounds like the ancient problem that is solved by the installation of the ballast resistor?
  Might give it a try, most coils will kick plenty but need the extra current due to drop of voltage at cranking.
  Just a thought, 

David Allen <davida1 at hiwaay.net> wrote:
  OK someone told me "1" is negative (to ignition module) and 15 is + (from
ignition key-switched power relay). Hope this is right.
I'm trying to find a coil that will hold up more then 6 months. I've had
terrible luck with the parts store knockoffs of the GM original coil - they
all "arc out" between the coil body and metal core frame. It gets a little
white spot there and after dark you can see it arcing. Then the car gets a
stalling issue.
I've relocated the coil to the fenderwall where it is cooler and tried
different brands and styles of coils and they all fail about the same. The
ignition module has been replaced with a factory Delco from the dealer.
This Bosch coil has the same primary DC resistance as the OEM coil but the
secondary has a little more DC resistance. Since there is more to a coil
than DC resistance, I'll have to see how it performs. It definately cranks
up easier than the old "arc'd out" coil.
Hopefully this Bosch unit will hold up better.

> Anyone know off top of your head which terminal is + and - on a Bosch coil
> from an 84 BMW 325.
> It's got "1" and "15"
> I looked breifly and can't find a diagram which shows the coil terminal
> numbers.
> Thanks,
> David

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