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> Bosch Blue Coil Issues
kpfoten
post Dec 13 2009, 04:20 PM
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Hello--

I replaced my coil a few months ago--it was no good. The new one worked until just tonight when the car died in the driveway. I am getting no spark, no reading from my timing light hooked to the coil-dizzy.

My test numbers: 3.1 ohms + to - and 12.07 kohms from either to center post (this is lower than the 15-30 kohms that is the range of normal in my vw book).
Key on, I get around 11.9v or so to positive terminal on the coil.

Is the coil bad? Are there things that can cause the coil to fry?

Confused.
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ME733
post Dec 13 2009, 04:31 PM
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(IMG:style_emoticons/default/popcorn[1].gif) ...No Spark at all......SEE IF THE POINTS ARE CLOSED UP....if they ARE CLOSED... set them to .016 ths.......and replace the points and condenser if they havent been replaced in a while. (IMG:style_emoticons/default/popcorn[1].gif)
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jmill
post Dec 13 2009, 04:34 PM
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Wikipedia explains things better than I can: The points allow the coil to charge magnetically and then, when they are opened by a cam arrangement, the magnetic field collapses and a large (20 kV or greater) voltage is produced. The capacitor is used to absorb the back EMF from the magnetic field in the coil to minimize point contact burning and maximize point life.

I would change the points and condensor first.
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kpfoten
post Dec 13 2009, 04:54 PM
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Oops... I should've mentioned that I recently installed a hot-spark ignition module and it ran great up until now. Still, shouldn't I at least have some output from the coil center post?
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ME733
post Dec 13 2009, 05:05 PM
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(IMG:style_emoticons/default/popcorn[1].gif) ... Nope!...the hot spark module , whatever that is , may need resetting, has a broken wire connector, or is ...BURNED out...it happens.....try reinstalling a NEW normal set of points and condenser and see what happens....Oh yea by the way...you Do have the rotor installed ...don't ya?. (IMG:style_emoticons/default/popcorn[1].gif)
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kpfoten
post Dec 13 2009, 05:21 PM
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I thing the hot-spark module is burnt out. I ran resistance tests on it per the website and it's no good. It ran great and then died suddenly.

(And yes, the rotor is installed (IMG:style_emoticons/default/smile.gif) )
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jmill
post Dec 13 2009, 07:36 PM
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They have a 3 year warranty. Turn that puppy in for a new one.
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kpfoten
post Dec 13 2009, 07:43 PM
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Yep! Sending it back tomorrow. I'm wondering if other people have had problems with hot-spark units failing?
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ChrisFoley
post Dec 13 2009, 08:09 PM
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If its anything like a Pertronix, they will fail if you leave the ignition on without the engine running for any length of time.
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kpfoten
post Dec 13 2009, 09:17 PM
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Yeah, I definitely didn't keep the ignition on. I seriously only had the hot-spark installed for 2 days and had been idling the car in the driveway for a total of 5-10 minutes before they burned up. I've heard that other people have had issues with these things.

I'd put points back in but my braided ground-wire is shot. I suppose I can change the base-plate or solder a new wire in. Ugh.
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Scott S
post Dec 13 2009, 09:24 PM
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QUOTE(kpfoten @ Dec 13 2009, 08:17 PM) *

I'd put points back in but my braided ground-wire is shot. I suppose I can change the base-plate or solder a new wire in. Ugh.


That, my freind, is what fried the unit - ask me how I know. I replaced my compufire twice before we found the problem. Car would run fantastic - then just stop. Fixed the grounding issue and have been fine ever since (1997).
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kpfoten
post Dec 13 2009, 09:30 PM
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Dang--no kidding! Somebody told me it wouldn't matter if that braided wire was gone. Guess they were wrong! Anyone know where I can get a new points plate combo? I think AutoAtlanta has 'em. Otherwise I will pull the dizzy and solder some braided wire back into place.
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Johny Blackstain
post Dec 14 2009, 09:34 AM
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I've heard several horror stories regarding fried coils because of points replacement modules. Pertronix installation instructions specify the coil output/polarity/etc... & the Bosch blue does not meet those specs, so I bought the coil to go along w/ the Pertronix & have had smooth sailing ever since. Had to peel off the sticker & spray paint it black for "concours sake", (IMG:style_emoticons/default/headbang.gif) , but it looks & works fine.
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