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Groundwires to the coils

 
Old 02-20-2019, 06:40 PM
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Pboden
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Default Groundwires to the coils

Since I can not get my -87 running, with no sparks to the plugs, I am continuing checking the ignition system for some obvious fault. For ones - unscrewing the wire from the coils pole, I see there is no continuity from the coils negative wire to any of the cars ground points. Is that correct ? Where are these wires coming from ?

Thanks
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Old 02-21-2019, 06:07 AM
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The Forgotten On
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The ground wires should have continuity. They connect to the engine and the engine connects through a ground strap under the passenger's side to the body of the car.

Most likely your straps are corroded and need to be replaced. I recently replaced mine in my 89. Not too expensive for the Porsche parts but they could be easily replicated for 20% of the cost.
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Old 02-21-2019, 06:28 AM
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I discovered that my port-side ground wire had broken to the point of having just as strand or two - metal fatigue from engine movement. I made up a new, longer, loopier wire and connected it to a more distant bolt on the engine.
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Old 02-21-2019, 11:04 AM
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Any change from the people who have changed? These wires always seemed so stiff to me so I figured age, corrosion, etc. wouldn't help with grounding.
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Old 02-21-2019, 11:27 AM
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Yes I believe that is correct, but let's be sure your question is properly understood and vetted

It seems the guys that are responding about the coil ground wires are talking about the radio suppression grounds, not your question about pole.
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Old 02-21-2019, 11:51 AM
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skpyle
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To my understanding, the (-) wire on each coil is not to be grounded to chassis. They are pulled to ground by the ignition amplifiers.
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Old 02-21-2019, 01:10 PM
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I think we are discussing two different ground wires
OP please post a picture of the ground wire you want info about before you connect or do any testing
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Old 02-21-2019, 04:38 PM
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I see that my question may be interpreted differently, but I believe "skpyle" answered it. Thanks

When negative wire is dismantled/ unscrewed from the coil, there is no continuity from wire to ground on chassis. When connected back to the coil, I do have continuity.
I had to confirm this is correct. One point of my speculation list.
(On my old 911 the coil wire is connected directly to ground. )

Thanks
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Old 02-21-2019, 11:46 PM
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I suspect that your old 911 had an aftermarket CD (Capacitor-discharge) ignition system fitted. Popular retrofit to carburetor and some very early injection cars with points-and-condenser ignition originally fitted.
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