Well, my theory (and I know some don't believe that) is, that when an ignition wire is broken, the voltage rises so high till the spark can jump. The energy is stored in the coil and when you stop the current in the primary coil, the current still wants to flow. Now the primary circuit is open and the current can't flow anymore under regular circumstances. The magnetic field in the coil induces a higher voltage in the secondary winding (also in the primary, but the switch in the primary circuit (points or transistors) can handle this). The voltage rises until the field strenght lets the spark jump at the weakest point (ionized air...therefore there's a difference in the max voltage if you have different air/gas mixtures around the spark plug). This should be the spark plug (therefore when you make the gap wider you get a higher voltage). Now let's say your main wire is broken - you have a second gap where the spark must jump over. The result is that the induced voltage in the coil is higher than under regular circumstances. The high voltage is also induced in the primary winding and may jump in the primary circuit somewhere. These extra needles that the tacho will see let it jump/move like crazy. And the car sputters because the spark jumps somewhere else but where it should - at your spark plugs ! Elvis & 6548 > Rich A. > > Did the new coil wire fix your tach flickering? > > If so, can someone explain to me(us) how a bad coil wire could > cause, "...the tach flickers even when parked and idling." > > My tach flickers at idle too. I will replace my coil wire let you > all know. > > Dave and 6530 > > -- NEU : GMX Internet.FreeDSL Ab sofort DSL-Tarif ohne Grundgebühr: http://www.gmx.net/dsl To address comments privately to the moderating team, please address: moderators@xxxxxxxxxxx For more info on the list, tech articles, cars for sale see www.dmcnews.com To search the archives or view files, log in at http://groups.yahoo.com/group/dmcnews Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/dmcnews/ <*> To unsubscribe from this group, send an email to: dmcnews-unsubscribe@xxxxxxxxxxxxxxx <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/