Help me please
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Junior User
Joined: Apr 2015
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That can't be right, the coil would be isolated with no way to complete a circuit. You could not measure any resistance. I did try it for you but the whole time I kept telling myself, you are trying to measure the resistance of air and as expected the meter did not move.
Lead Driver
Joined: Jul 2009
Posts: 6,477
Likes: 19
From: Sheffield, AL
Hello, peka!
well I could have gone thru it all for you here but it is 3 pages long, and I thought that you might get more out of it if you read it. It takes about 15sec to do the search. But I'm sorry for causing so much hardship. I will copy it all and post it here if that's what you want. It was determined by the moderator and others at the time I did not need to add a resistor because the resistor wire was working and my coil was within limits.
Each member's time is equally valuable and each of us should want to do whatever we can to provide the pertinent information as quickly as possible. I believe that is what ctubutis was asking for. You have been receiving assistance from some "heavy hitters" within our forum family. They have a wealth of knowledge and are willing to share it with those of us needing help.
I hope this makes sense and that you do not mind me in my attempt to keep our happy family happy! Have a good day and I will be following your progress.
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Junior User
Joined: Apr 2015
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As it turns out both coil and ICM were bad. I replaced them with Echlin parts. I have some concerns regarding the measurements taken. Coil primary was 1.2 corrected, voltage to coil + engine off key in run was 7.2v, after driving to warm it up I checked coil + with engine running and it was 10.5v, I checked battery it was being charged at 13.7v( I'm not sure this matters but maybe it does) Does this sound like I need an external resistor and bypass wire?
Cargo Master
Joined: Mar 2008
Posts: 2,573
Likes: 207
From: Washington
As it turns out both coil and ICM were bad. I replaced them with Echlin parts. I have some concerns regarding the measurements taken. Coil primary was 1.2 corrected, voltage to coil + engine off key in run was 7.2v, after driving to warm it up I checked coil + with engine running and it was 10.5v, I checked battery it was being charged at 13.7v( I'm not sure this matters but maybe it does) Does this sound like I need an external resistor and bypass wire?
Coil primary of 1.2 ohms is fine.
Things the 7.2 volts reading tells you are...
The resistor wire is dropping 5.3 volts, coil is dropping 5.9 volts and the last item in the circuit is the DS2 module is dropping 1.3 volts ... which all adds up to the applied voltage of 12.5 volts. The calculated value of your resistor wire is 1.08 ohms, base on the above numbers.
The reads / numbers are all in the safe range.
At idle, 10.5 volts coil positive with 13.7 volts supplied ...
The DS2 1.3 volts drop is a fixed. The resistor wire and coil combo drop the remaining 12.4 volts at a 47% / 53% proportional split ... so the resistor wire is dropping 5.87 volts at idle. 13.7v - 5.87v = 7.82 volts which is the lowest the voltage ever is at the coil postive.
The voltage at the coil positive is really a square wave with a 50% duty cycle (based on a dwell of 30deg) with the top of the square wave being 13.7 volts and the bottom of the square wave being 7.82 volts. The meter is trying to average the square wave and thus you read 10.5 volts.
My mathematical analysis yields 10.75 volts for this example but I guessed on the 50% duty cycle, it could be 45/55 split.
So I think it is fine as is, nothing else is needed.
Jim
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Junior User
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Wow I'm impressed at your math skills. Thank you for your expertise. And thanks to all you other experts who have helped me with this problem. I'm sure we will be chatting again, oh yea I have another, ah new thread time.
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