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Re: Summary, Coil voltage/missfiring. by Sam Watson
Post New Message The jumper wire and the vacuum disconnect tested two things. The vacuum disconnect was to test, more or less, if the problem was caused by too much change in the pickup-reluctor air gap as the pivoted mounting plate was pulled around by the vacuum "can". The jumper wire proved that your problem is ChryCo's somewhat enemic ignition system, something we, (meaning the guys in the shop), had to contend with when we were converting our fleet to dual-fuel operation in the late '70's. In our case, the altenate fuel was compressed--3,200 PSI--natural gas. "Dry gas" puts a terrible demand on an ignition system as there is no conductivity to it, as in a "wet" fuel. Even running gaps of.020" or less, the Dodges wouldn't ignite the fuel charge. As the oscilliscope showed, the ChryCo solid state ignition was putting out between 17,000 to 20,000 volts on open circuit. Compare that to the old point type system that it replaced which could make 32,000 open circuit voltage. Two things caused this, one being that the coil is "on", or has current flowing through it most of the time---it's really only "off" for about 3 degrees of dwell--this really keeps the coil very hot, which equals resistance. The coil is the other problem, ChryCo just used the same coil as their old system used, other mfgr's used a different design coil for their solid state ignition. So let's take your resister-type spark plug wires at 1,000 ohm resistance per inch, more or less, and run what little current comes out the end through a resister spark plug which contains a 10,000 ohm carbon resister. By this time there isn't much "juice" left in old sparky to make it across the gap. What we found was a trick that the off-road racer guys used. That was to use non-resister plugs, gapped at.032", move the coil to where it gets good air flow---even seen them mounted in the cold air intake duct-- and buy a ballast resister for the old point set ignition, mount it near your dual one, and run jumper wires between both ends of the coil feed side of your dual resister over to both ends of the new single resister so that you have these resisters parallel, which halves the resistance. We never had any problems with the coils after doing this, scope tests showed the ignition system was now making 26,000-28,000 open circuit voltage and firing the plugs nicely.You most likely were getting shocks from the key due to the fact that there is a connection betwwen the primary and secondary windings in the coil. Most likely, when the current voltage couldn't "push" across all that resistance, it discharged through whatever path it could find, though I've never heard of it "zapping" the key, but why not?
All Messages in ThreadAuthorDate
Post New MessageSummary, Coil voltage/missfiring. Ralph 8-1-02  
  Reply to MessageRe: Summary, Coil voltage/missfiring. Ralph 8-2-02  
  Reply to MessageRe: Summary, Coil voltage/missfiring. Joe 8-1-02  
    Reply to MessageRe: Summary, Coil voltage/missfiring. Bob 8-1-02  
    Reply to MessageRe: Summary, Coil voltage/missfiring. Ralph 8-2-02  
      Reply to MessageRe: Summary, Coil voltage/missfiring. Sam Watson 8-2-02  
        Reply to MessageRe: Summary, Coil voltage/missfiring. Ralph 8-3-02  
          Reply to MessageRe: Summary, Coil voltage/missfiring. Sam Watson 8-4-02  
            Reply to MessageRe: Summary, Coil voltage/missfiring. ralph 8-4-02  
              Reply to MessageRe: Summary, Coil voltage/missfiring. Ray 8-4-02  
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