×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Ignition coil; heat as evil or resistance as evil

Ignition coil; heat as evil or resistance as evil

Ignition coil; heat as evil or resistance as evil

(OP)
I'm tinkering again, I moved my ignition coil away from its stock position (and the heat of the engine), so now it's as cool as a cucumber. I measured the resistance in the new coil wire just to make sure I had good connections and was flabergasted at the reading. Where 1.000 is bad and .001 is good, my reading was .819. Then I measured other wires of shorter lengths and saw progressive improvement.

So the question is: will the cool coil's power overcome the increased resistance, or would the coil rather be hot with less resistance? Thanks for your feedback.
Dave

RE: Ignition coil; heat as evil or resistance as evil

Does it make that much difference?  It might matter with a stereo system. but surely the series resistance of the spark gap dominates everything.  After all, don't resistor wires for EMI suppression still work?

TTFN

RE: Ignition coil; heat as evil or resistance as evil

You've either got a wiring problem or a measurment problem.  16 ga. wire has a resistance of 0.004 Ohms/ft. (I'm assuming that we are talking about the wire to the coil primary).

RE: Ignition coil; heat as evil or resistance as evil

(OP)
IRstuff and sreid, thanks for the feedback.
  
IRstuff, as to the question, does it really make a difference...that's basically my question.  I take it that you don't think it makes a  big difference.  Right?

sreid, as to the point about wiring vs. a measurement problem, I believe I've used the wrong terminology...I should have said that I measured the continuity of the coil wire (the spark plug type wire that runs from the distributor cap to the coil).  In my case the new wire is much longer than the old one, and instead of continuity being .001 or very close, it was .819.  Sorry if I confused the issue.  Dave  

Dave

 

RE: Ignition coil; heat as evil or resistance as evil

Agreed.  The wire resistance should be irrelevant to the spark generation problem.

One note about resistance measurement.  There may not be anything wrong with the resistance of the wire.  My personal experience is that resistances less than 1 ohm generally require 4-point resistance measurements, as the contact resistance of the probes to the wire will tend to dominate the measurement.  

The basic 4-point measurement requires using 2 connections on either end, running a current through one set and measuring the IR drop through the other set.  This approach eliminates the contact resistance error in the voltage measurement.

TTFN

RE: Ignition coil; heat as evil or resistance as evil

(OP)
To IRstuff, thanks a lot for the links to those other websites, they are very helpful.
Dave

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources