voltage reading on coil
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From: panama city
voltage at coil
im having trouble getting my carbuerated 302 running right. when i take voltage reading at the positive side coil while running its showing 9 and 1/2, when i test negative side its showing about 4. should the neg side be showing anything? the battery is charged, its a new coil. could it be my ignition module. does my problem lie somewhere here or should i start looking elsewhere? thank for any help
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From: Virginia
Those readings sound good. There is a resistor in the coil + feed that reduces the voltage down to the 9.5 you are getting.
You are getting weird readings on the negative of the coil, because the - of the coil is not ground. The - of the coil is controlled by the ignition box (or points in and older vehicle) which ground and then un-ground the - of the coil.
What are your problems?
Hard to start?
Idles rough?
No power on hills?
Hesitates when you take off?
You are getting weird readings on the negative of the coil, because the - of the coil is not ground. The - of the coil is controlled by the ignition box (or points in and older vehicle) which ground and then un-ground the - of the coil.
What are your problems?
Hard to start?
Idles rough?
No power on hills?
Hesitates when you take off?
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From: panama city
idles rough, when i put in drive it really starts to run rough, when i gas its even worse.should i try another ignition module. there are two other wires going to my neg on coil. are there supposed to be two. i put this wire kit in myself for the first time. i had no experience. last week it was running good. it was the first time ive driven it since i got it running. do you think i fried the ignition in the time it was running good. how do i make sure my grounds are good.
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From: panama city
i put new ign module on, still getting positive voltage reading from the neg side of coil. does my ignition module need to be completly mounted to grouded area in order to get proper grounding. is the back side of the module the ground.{the frame casing which goes right up against the firewall where i am mounting}
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Junior User
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From: panama city
voltage reading on coil
could someone please tell me if i am supposed to have any positive voltage on the negative side of my coil? i keep getting a reading of 2 when key turned on and about 4 when engine running. when i run a ground wire straight from neg. on battery to it. it does eliminate reading, but the engine will not fire up. the ignition is a setup i bought from davis unified ignition {makers of the dui ignition}. my setup is not like those though, i have distributor and a separate module and a coil. i have found out that the ignition module they sell with my kit is actually a chrysler box with the 4 wires.
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Yes, it's normal. Whether you have points or an electronic ignition, both systems work by grounding and breaking the ground to the coil. When the coil is grounded, current flows through the primary winding and a magnetic field is created. When the ground connection is broken (points open) current stops flowing and the field collapses. The field collapses faster than it was built and that and the difference in coil windings stepps the voltage up and the plug is fired.
When you grounded the coil to the battery, you bypassed the points or electronic coil trigger circuit. Current flowed through the coil and the magnetic field built up. Then the current continued to flow and the magnetic field remained static, so the plug was never fired. Coils and transformers work on moving magnetic fields. If the field is not building or collapsing, then engery is not transferred through the coil.
When you grounded the coil to the battery, you bypassed the points or electronic coil trigger circuit. Current flowed through the coil and the magnetic field built up. Then the current continued to flow and the magnetic field remained static, so the plug was never fired. Coils and transformers work on moving magnetic fields. If the field is not building or collapsing, then engery is not transferred through the coil.
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From: Virginia
idles rough, when i put in drive it really starts to run rough, when i gas its even worse.
I am assuming you have a carb. What are you working on?
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From: panama city
ive got a 5.0 crate engine from ford,600 holley,aod,ford racing headers.nothing special on engine,its the 97 explorer 5.0 with the gt40p heads. i put it into my 1949 f1 pickup.i have purchased practically everything new on the truck but cannot get it running on the road. this is my first project ever and everything i do takes me five times as long with a whole lot of trial and error. the errors {or what i assume to be} are making me broke.
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From: Easton,Ks
Originally Posted by pageparsley
idles rough, when i put in drive it really starts to run rough, when i gas its even worse.should i try another ignition module. there are two other wires going to my neg on coil. are there supposed to be two. i put this wire kit in myself for the first time. i had no experience. last week it was running good. it was the first time ive driven it since i got it running. do you think i fried the ignition in the time it was running good. how do i make sure my grounds are good.
Here is the way it should be wired.
Last edited by subford; Nov 25, 2005 at 11:16 AM.
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