Technical Tips > Electrical-Electronics-Air-Lighting-Guages-Security-Vacuum

Spark and coil lead resistance readings

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Vettech:
Well Well Well, yes! not a simple system. Each item can give a lot of problems.

1. With high energy systems crossfire can be a real issue, on cap, plugs, but also where leads cross or touch earths, look for holes/damage.
2. Solid wire are not an issue if,
    a- large earth braid is used to earth the radio case. To a SOLID EARTH thats a clean earth - no paint.
    b- capacitor/condensor is connected near radio - from (radio)  power +12v to earth. (2uf 50volt working or greater)

If miss is at idle, pulling leads is great on 4 and 6's, but harder on 8's, but sometimes works.

Coils -  you may need to defer to the maker, normally low primary and much higher secondary (spark side).

But your electronics could be breaking down, also points - be they Optical or "Hall Effect" (magnetic) could also breakdown.
Had a car once where the reluctor pick up was loose in the dissy.
You can also use a Laser Temp gauge pointed at each Exh port looking for one with a lower temp.(not firing as much).
This only works if the miss is in one cylinder only.


BOB = "Best Of Brittish"

bfit:
Did I read this car has a 6al that will put out 530 volts and 135mJ of spark energy
I'd be careful  when pulling leads

Vettech:
Yes Bfit is correct, and of course this is only the Primary side.
However you should not be able to come into contact with this.

BUT!...

The Secondary side is around 45,000Volts and this will be at the plug.

Contact with this could be lethal especially if you have health issues.
The main issue with this type of cct design is that it will continue to pump out the volts and constant current even into your now limp body.

Be wary,

bfit:
Health problem
Like holding on to the spark plug lead.
And that sucker will jump a long way
 And deliver full voltage for 20 deg crank

Matt G:
Ha, ha. So using my tongue (like on a 9v battery) isn't a good idea.....
Pulled my plugs today, and measured the resistance on all leads. #6 plug was bad, all others were good, which was strange because I'm sure that #2 was less than finger tight (still not sure how, but I'm glad that I found it).   Leads were all good for resistance and in sync with lead length (ranging from 1.15 to 1.97 kOhms) however I did notice that my lead on #6 had 3 different arc points and burning within about 3" of the und of the spark plug boot.  I cut the lead down past the last burn/crack, and re-crimped an end on.
I should now have plugs, leads, and distributor cap all good. Will go for a test run next weekend to see if I need to keep working on options for errors.
Thank again for the feedback!,

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