Gary Lewis Posted June 7, 2020 Share Posted June 7, 2020 Good morning Jesse. 1.2 Ohms seems a little high (1.05-1.15 is spec) but that could be down to a little oxidation in a connector or even the leads of your meter. Remember, you're not testing by putting any kind of real load on the system. But you have proven that the resistance is there. Yes, you've proven the resistance wire is in place. And the difference between 1.1 and 1.2 ohms could be the leads, as Jim suggested, or just the difference in meters. Low resistance like that is really hard to measure accurately. As for the 10.5 volts you are measuring while the engine is running, I think it is a red herring. The ringing will vary by the coil that you have and whether or not you have a condensor/capacitor snubbing it. And different meters will probably give different readings because the chip in them computes the DC reading differently. But I think you've answered your question - the resistance is there and your system is working correctly. Link to comment Share on other sites More sharing options...
Jesse3877 Posted June 7, 2020 Author Share Posted June 7, 2020 Good morning Jesse.1.2 Ohms seems a little high (1.05-1.15 is spec) but that could be down to a little oxidation in a connector or even the leads of your meter.Remember, you're not testing by putting any kind of real load on the system.But you have proven that the resistance is there.Jim, Yes meter was a little back and forth between 1.1 and 1.2 (after I adjusted for meter lead resistance) Before I close the case on this, I would like to know the best way to measure the resistance of the full circuit ignition circuit with key in run position. I’d like to do some ohms law and try to figure out how much amps is in the circuit and then contact pertronix to see how many my flamethrower coil can handle. I will say that as my engine rpms increase so does my input voltage at coil. I know the test is not going to be perfect but surely it will give me an idea and I would enjoy the exercise. So in your opinion, what two points should I use to make my resistance test measurement? Main battery ground and coil (+)? Thank you,Jesse Link to comment Share on other sites More sharing options...
Jesse3877 Posted June 7, 2020 Author Share Posted June 7, 2020 Sorry Gary, You responded to me while I was typing my response to Jim. Thank you for your reaffirming I’m out as it is most valuable. Warm Regards,Jesse Link to comment Share on other sites More sharing options...
Gary Lewis Posted June 7, 2020 Share Posted June 7, 2020 You can check by tapping the distributor with a screwdriver handle. That should be enough to trigger the module. In fact this is the Ford diagnostic procedure. You are absolutely right! I'd not ever seen that. The EVTM says: Link to comment Share on other sites More sharing options...
Jesse3877 Posted June 7, 2020 Author Share Posted June 7, 2020 *reaffirming input Jesse Link to comment Share on other sites More sharing options...
Gary Lewis Posted June 7, 2020 Share Posted June 7, 2020 You can measure the current if your meter has a 10 amp or larger scale. Just put it in series between the positive of the coil and the red/light green wire and turn the key on. E=IR so I=E/R. If battery voltage is 12.6, the resistance is 1.1 and the coil is 1.5, then 12.6/2.6 = 4.9 amps. But, I don't think you'll measure that 'cause the DS-II module has a voltage drop across it. Assuming it is the standard .7v for a transistor then voltage = 11.9 and the current may be more like 4.6 amps. Link to comment Share on other sites More sharing options...
Jesse3877 Posted June 7, 2020 Author Share Posted June 7, 2020 You can measure the current if your meter has a 10 amp or larger scale. Just put it in series between the positive of the coil and the red/light green wire and turn the key on. E=IR so I=E/R. If battery voltage is 12.6, the resistance is 1.1 and the coil is 1.5, then 12.6/2.6 = 4.9 amps.But, I don't think you'll measure that 'cause the DS-II module has a voltage drop across it. Assuming it is the standard .7v for a transistor then voltage = 11.9 and the current may be more like 4.6 amps.Gary, Thanks for your response. I’ll probably try using one of my Meters as they both can handle up to 10A. Jesse Link to comment Share on other sites More sharing options...
Gary Lewis Posted June 7, 2020 Share Posted June 7, 2020 Let us know what you find, please. Link to comment Share on other sites More sharing options...
Jesse3877 Posted June 7, 2020 Author Share Posted June 7, 2020 Let us know what you find, please. Hello, reporting back my amperage results. With key RUN and engine OFF= 3.7AWhile normal cranking= 5AEngine running @700 rpms= 2.7AEngine running @2000 rpms= around the same, no more than 3A. My baby went down for a nap and could feel my wife’s eyes burning through the back of my head so had to quickly stop making noise. I saw something online that peak amps for my new PerTronix flamethrower coil is 7.2A however that’s from a third party website. It’s replacing an old dirty Mallory 1.4 ohm coil. I need to go for a long drive and see how it starts when hot. The old Mallory struggled to fire when hot. Thanks again for your help Jim & Gary!Jesse Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted June 7, 2020 Share Posted June 7, 2020 I'm very glad to hear things are working. You've done some good diagnosis and now have a better understanding of how your ignition system works. You even surprised me with the 25 Ohm reading, but my '87 is wired a bit different. If your power while cranking is running from the (I) terminal I see how that makes sense. Link to comment Share on other sites More sharing options...
Recommended Posts