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On 31 Jul 2001, at 9:19, Mark Fuhriman wrote: > What can cause a fairly new (~3yrs old) Bosch "blue" ignition coil to > fail? Did the blue coil supersede the OE coil? Can I keep that old > Borg Warner coil on my car or am I better off with another Bosch blue > coil? Or can I get an OE "black" coil anywhere? Nice goin! You must still be carrying that rabbit's foot. ;-) It's very unusual for a coil of any kind to fail. I've never seen a bad one, but I know that it does happen. I'd be interested to know whether your primary and secondary still measure with good continuity or not. The coil you have on there now is probably not a good choice to leave in place. Chances are that it was designed to have a series resistor with it, which was something that VW never did. With this in mind, it's possible that Bosch makes more than one kind of Blue Coil, and that you need the right one to work correctly (and live a long life) on a VW. I have several old, good OE black coils here, as well as a couple of VW Blue coils. I seem to recall looking at the part # stamped on the base of some of these and noticing that some of the OE coils had the same part # as the blue coils, just not the blue paint. I'd have to check that again to be sure that I'm correct on that. BTW, I worked up a MathCAD program a few years ago to look at the spark energy in the OE coil vs. that in the Blue coil. The Blue coil has an advantage, but only above 6000 rpm, IIRC. At 6000 rpm both coils still have about 10x the spark energy available that Bosch claims is needed to reliably set off cumbustion, so this really isn't something that any street car can use to advantage. - Jim Adney jadney@vwtype3.org Madison, WI 53711-3054 USA ------------------------------------------------------------------- Too much? Digest! mailto:type3-d-request@vwtype3.org Subj=subscribe