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The dreaded green wire
So I am suspicious about the green wire on the dizzy for my 930 - no spark at the coil. Swapped coil and CDI from working units, same result.
Wanting to test the wire. Not sure how. My wiring diagram shows a 2 pin connector on that circuit between the dizzy and the CDI. I don't recall seeing one previously and my book does not tell me where it is located. Any one got any clues on the 2 pin connector, and how to test the green wire? Thanks Alan
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83 SC, 82 930 (track) - Stock except for RarlyL8 race headers, RarlyL8 Zork, K27-7006, 22/28 T bars, 007 Fuel head, short 3&4 gears, NGK AFR, Greddy EBC (on the slippery slope), Wevo engine mounts, ERP rear camber adjust and mono balls, Tarret front monoball camber adjust, Elgin cams, 38mm ported heads, 964 IC. 380rwhp @ 0.8bar Apart from above, bone stock:-) |
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01-06-2024, 07:32 PM
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Do a search for testing that wire, should get many threads on the topic
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01-07-2024, 09:22 AM
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Right, so I have hunted round and come up with the following.
It seems you shouyld get 600 ohms on terminals 31d and 7 on the CDI box. This is assumed to be an in spec green wire. I have now pulled the green wire 'out'. I got 600 ohms intitally and the car fired up and then died a minute or two later. I checked the ohms again and got like 900. Weird. I checked it over the next hr or so and got up to 4k ohms. This would sugest the green wire is at fault. So I pulled it. Now I can link to each terminal end on it (the CDI terminal and the dizzy terminal)- and get 0 ohms on each leg of the wire. So no broken wire here. That suggests the resistance is inside the dizzy that the wire plugs in to. It is basically a simple 2 pin coax cable linking the trigger unit in the dizzy. This would suggest the unit in the dizzy is at fault? Not sure what that bit is, haven't pulled the dizzy down yet. Anyone have any clues what the bit in the dizzy is that the green wire links too? Thanks Alan
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83 SC, 82 930 (track) - Stock except for RarlyL8 race headers, RarlyL8 Zork, K27-7006, 22/28 T bars, 007 Fuel head, short 3&4 gears, NGK AFR, Greddy EBC (on the slippery slope), Wevo engine mounts, ERP rear camber adjust and mono balls, Tarret front monoball camber adjust, Elgin cams, 38mm ported heads, 964 IC. 380rwhp @ 0.8bar Apart from above, bone stock:-) |
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01-07-2024, 12:41 PM
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OK, found the problem - the dreaded green wire - right at the connector end in the dizzy. Something not right in there - erratic ohm readings.
So the green wire is just a simple coax wire linking to the two terminals in the dizzy. These terminals atre the ends of a very large fine wire coil in the body of the dizzy. They provide the 600ohm. Now to find a spare green plug off a dead Merc. No time to order one right now. Regards Alan
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83 SC, 82 930 (track) - Stock except for RarlyL8 race headers, RarlyL8 Zork, K27-7006, 22/28 T bars, 007 Fuel head, short 3&4 gears, NGK AFR, Greddy EBC (on the slippery slope), Wevo engine mounts, ERP rear camber adjust and mono balls, Tarret front monoball camber adjust, Elgin cams, 38mm ported heads, 964 IC. 380rwhp @ 0.8bar Apart from above, bone stock:-) |
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01-07-2024, 01:49 PM
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Join Date: Jul 2013
Location: Brisbane, Australia.
Posts: 2,582
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Always learning. www.aircooledporsches.com.au See me bumble my way through my first EFI and TURBO conversion! https://youtu.be/bpPWLH1hhgo?si=GufVhpk_80N4K4RP |
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01-08-2024, 02:06 AM
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You will need to remove the distributor to unplug the wire, so make sure you set it at TDC with #1 cylinder firing before you remove it to make life easy. No big deal if you lose the timing you'll just have to set the timing from scratch; it can be tricky to know whether the engine is firing on #1 or #4 when at TDC. Various ways of doing it; I remove a valve cover and check the valves.
Roy
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1959 Bristol 406 (bought in 1972; sold in 1977) 1966 Porsche 2.0 coupe (bought in 1977; sold 1981) 1978 Porsche SC coupe (bought in 1993) |
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01-08-2024, 05:40 AM
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Thanks for the tip - I had set it to #1 - but had forgotten the #1/4 bit.
Will have to check. The wire had broken inside the entry to the plug - impossible to see. Thanks Alan 
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83 SC, 82 930 (track) - Stock except for RarlyL8 race headers, RarlyL8 Zork, K27-7006, 22/28 T bars, 007 Fuel head, short 3&4 gears, NGK AFR, Greddy EBC (on the slippery slope), Wevo engine mounts, ERP rear camber adjust and mono balls, Tarret front monoball camber adjust, Elgin cams, 38mm ported heads, 964 IC. 380rwhp @ 0.8bar Apart from above, bone stock:-) |
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01-08-2024, 08:36 AM
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So I managed to salvage the old dizzy plug, chopped out the broken bit of wire and put back together, with a 2 pin connector for when I source another green dizzy plug. Checks out ohm wise.
I did set the rotor to the #1 firing mark on the dizzy body before pulling it, so it should be easy to fit back. Didn't pay attention to the Z1 mark - just the dizzy rotor. I have a mark on the rotor that needs to line up with the groove on the dizzy body. If I am out by a tooth, I will definitely know it. Regards Alan 
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83 SC, 82 930 (track) - Stock except for RarlyL8 race headers, RarlyL8 Zork, K27-7006, 22/28 T bars, 007 Fuel head, short 3&4 gears, NGK AFR, Greddy EBC (on the slippery slope), Wevo engine mounts, ERP rear camber adjust and mono balls, Tarret front monoball camber adjust, Elgin cams, 38mm ported heads, 964 IC. 380rwhp @ 0.8bar Apart from above, bone stock:-) |
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01-08-2024, 01:50 PM
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Porsche
Porsche
