[DeTomaso] more evidence I'm a not much of a mechanic...

[Asa Jay Laughton]

Well no, that's the problem.  The spark seeks a ground by jumping the 
gap in the plug from the center electrode to the outside threaded 
portion which grounds against the block.  If you pull the spark plug 
wire off the plug, there is no route to ground via the wire.  That means 
the spark will try to "seek" a new ground, possibly through any circuit 
boards in your MSD, or possibly to another spark plug wire in the cap.

I don't know MSD ignition, so I really don't know the dangers here.  But 
after seeing how many folks have toasted an MSD just by welding on the 
car, even after disconnecting the battery, I'd be shy of doing this.

Asa Jay

Asa Jay Laughton, MSgt, USAFR, Retired
& Shelley Marie
Spokane, WA
******************************     
http://www.asajay.com   ***   http://www.teampanteraracing.com
  



Christopher Kimball wrote:
> That's exactly right--I don't want to pull the plugs since that's such 
> a royal pain in the rear.  If I did pull a plug, it would be no 
> problem, since then the ground would be easy; the plug casing grounded 
> with the wire still hooked up would simply let me see the spark plug 
> sparking its little heart out...
>
> The problem with the signal sensor you mention is that it only shows 
> the power, not whether or not the plug is firing.  I'm pretty sure the 
> electronic ignition is not the problem.  Once I figure out which 
> cylinder it is, then I can pull the corresponding plug and see what it 
> looks like.
>
> It seems as if I just take off a plug wire and make sure it doesn't 
> touch anything, that shouldn't hurt anything, should it?
>
> Thanks,
>
> Chris
>
>
>
> Sincerely,
>
> Chris
>
> > Date: Fri, 19 Feb 2010 20:30:02 -0800
> > From: asajay at asajay.com
> > To: detomaso at realbig.com
> > Subject: Re: [DeTomaso] more evidence I'm a not much of a mechanic...
> >
> > Jack, the trouble is he doesn't want to pull the -plug-, just the
> > wire. I'm not sure how I'd do that with an MSD.
> >
> > My dad used to have this cool little gizmo. It looked like a pen but
> > was actually a spark detector. You held it next to the plug wire and it
> > would flash in time with the energy going to the plug. Something like
> > this would at least tell you there is spark going to each plug.
> >
> > Have you tired pulling the plugs to inspect them? Sometimes just
> > looking at the plugs will tell you what's going on.
> >
> > Asa Jay
> >
> > Asa Jay Laughton, MSgt, USAFR, Retired
> > & Shelley Marie
> > Spokane, WA
> > ******************************
> > http://www.asajay.com *** http://www.teampanteraracing.com
> >
> >
> >
> >
> > JDeRyke at aol.com wrote:
> > > In a message dated 2/19/10 6:28:19 PM, chrisvkimball at msn.com writes:
> > >
> > >
> > >> when you say I should run the spark plug wire to ground, do you 
> mean that
> > >> once I remove the wire from the plug I should actually run the 
> spark plug
> > >> wire directly to ground, and that won't damage anything?
> > >>
> > >>
> > > Attach a ground wire with an alligator clip to the ground lug on 
> the plug
> > > base so the plug works normally but is outside the engine. 
> Otherwise, the
> > > built-up energy in the MSD and coil will have no place to go .... 
> until it
> > > punches a hole in a circuit board to ground inside the box. Good 
> luck- J DeRyke
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