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Wed Nov 26, 2014 3:06 pm

I have a 12V Bosch Blue coil w/o internal resistor on my Single port 1600 Beetle. When I changed my oil cooler seals I didn't mark my wires very well and now I think I fried my ignition module (engine will not start & no spark). When my local shop tested the coil (to make sure it wasn't fried) they said I need a coil with an internal resistor or an external ballast resistor, but does not know which resistor I would need. Now the coil he has with the internal resistor is $94. I have seen external resistors for like $15 on the web. How would I figure out which external resistor I need so I can save some $$ or would it be easier/better in the long run just to get the coil with the internal resistor?

Thanks for all the help

Wed Nov 26, 2014 3:31 pm

:idea: Your in AZ so hopefully a Parts house would have a 12V coil for the bug. A VW engine will run with Any old style 12V coil with spade connections would work in a pinch....Bosch is not God when it comes to coils.

Did that when having problem returning from Mexico City. Stopped in Mazatlán....they did not have what I wanted but did have a coil which took me back to Calif. With all the BUgs in Mexico could not believe they did not have the right coil.

(VW Mechanic)

Wed Nov 26, 2014 5:03 pm

Welcome to The Samba.

If you have installed a points replacement module inside the distributor and hook up the +/- wires backwards you will instantly short out and destroy the module.

For your VW all you need is a standard black 12V Bosch replacement coil. The Bosch 12V blue coil (Made In Brazil) is higher voltage. A 3 ohm Pertronix flamethrower coil will also work.

http://vwparts.aircooled.net/12V-Bosch-Blue-Coil-with-Mounting-Bracket-00-012-p/00-012us.htm

http://vwparts.aircooled.net/Pertronix-Flamethrower-Ignition-Coil-Chrome-Oil-p/40501.htm

http://vwparts.aircooled.net/Pertronix-Flamethrower-Ignition-Coil-Black-Oil-p/40511.htm

Wed Nov 26, 2014 7:01 pm

Thanks for the replies. The wires that got mixed up were not the ones for the ignition module but the ones coming from the fire wall. I have been told that one is for the oil pressure light and the other is power for or from the ignition. Since I didn't mark them very well, I could get either the oil light to come on when I turned the ignition switch to on and not get the engine to start or no light and the engine would start. Who ever had the bug before me made both of those wires blue.
I forgot to turn the switch off when I was messing with the wires and heard a zap. Then it wouldn't start no matter what I did. Which makes me think the module is fried since I don't have spark at the plugs. I have looked at the Blue Bosch you linked and it looks identical to the one the shop showed me for almost half the price. The ignition module that is in the bug is one from EMPI. That's all the shop sells. Does it matter with which coil I get (as long as it has an internal resistor right) to work with the module I have? I don't want to fry any more parts and flush money down the drain.

Thanks again for all the help!

Wed Nov 26, 2014 7:29 pm

Having the polarity reversed will quickly destroy the points replacement module, but it will not harm the coil. Do not waste your money on a new coil, your existing one should still be fine.

Wed Nov 26, 2014 8:36 pm

Thanks Luft. My currrent coil does not have an internal resistor. I was told that if I dont have a resistor that the coil output will eventully fry the module.

Thu Nov 27, 2014 9:07 am

omegared11211 wrote: Thanks Luft. My currrent coil does not have an internal resistor. I was told that if I dont have a resistor that the coil output will eventully fry the module.

Lots of old wives tale about needing resister.... Believe there is only ONE model of Pertronics that requires a resistor.... I run Comupfire module direct on 12 volt "blue" coil (no external resistor) ... 12 years and still going.... Also on race car for the 6 years I had it.......

Some modules do state the minimum coils resistance (in ohms) they will work with without external resistor if coil meet spec......

Best you can do is go to website for ignition module and read their requirements... IF it requires a resistor use one, if it requires a coil of certain resistance then use one or add resistor to come up to their spec.... IF they do not state you need a resistor or coil of certain value, then its pretty safe no resistor or special coil value (ohms) is needed....

Dale

Thu Nov 27, 2014 7:31 pm

Thanks Dale. I have the Accu-Fire module and a Bosch 12V Coil without an internal resistor. Now I already have to buy a new module. To save money so I don't have to buy a new coil with a resistor (like the module maker recommends) how do I figure out which external resistor I need? .8 Ohms, 1.4, 1.6...?

Thu Nov 27, 2014 7:58 pm

Measure the resistance of the primary side of your coil. If it is 3.4 ohms or more you will not need an external resistor.

If it measures less than 3.4 ohms, subtracting that number from 3.4 will give you the value of the resistor that will be needed.

http://www.mamotorworks.com/VW/product/empi-accu-fire-electronic-ignition-kit

Thu Nov 27, 2014 7:59 pm

You want near three ohms.
resistance works by addition. for instance a 1.5 ohm coil plus a 1.5 ohm resistor equals 3

It is better to get the correct coil. They do not have "internal" resistors, they have smaller wire. it should cost about 30-40$

Fri Nov 28, 2014 11:11 am

Thanks for all the help. Guess I will just bite the bullet and get a new coil also. When I test my coil I get 2.7 ohms, when the shop tested it they got 5. Guess my walmart special meter is off.

thanks again for all the help.

Fri Nov 28, 2014 11:23 am

omegared11211 wrote: Thanks for all the help. Guess I will just bite the bullet and get a new coil also. When I test my coil I get 2.7 ohms, when the shop tested it they got 5. Guess my walmart special meter is off.

thanks again for all the help.

Did you "zero" meter before testing...

Dale

Fri Nov 28, 2014 12:19 pm

Did the shop zero their meter ?

The resistance of the coil you measured seems more accurate than the shop.

Not surprising, you care, the guy in the shop may well be wishing they were not there.

Sounds to me like the coil is OK and you fried the module.

Replace it or for now dig out the points and condensor you have in the spares kit in the glove box..