Help, No Spark!

Elfer · 12-06-2003, 10:23 AM

Ok, I recently installed a 3L engine on my SC but the harness was cut so I had to re-wire the whole thing. I hooked up the 6pin harness to the CD, and wired the harness back to the rest of the engine harness. 1. Red - (Hot) 2. White - (+) on coil, 3. Brown/White (-) on coil 4. Brown (ground) 5. Black/Violet - (tach) 6. Green (distributor optical trigger). Am I missing something here? If all wires are connected properly, I should get a spark.
The CD box whines when the car is on.
Anyone have any input?
Thanks.

emcon5 · emcon5's Garage

The green wire to the dizzy is coax, and splits to 2 terminals on the CDI.

Look at the wiring diagram here:
http://www.pelicanparts.com/911/911_Parts/Electrical/911_electrical_82SC_Part1-2.jpg

There should be a picture on the side of the Bosch box showing which terminal is which.

Tom

Leland Pate · 12-06-2003, 11:10 AM

Check your pulse generator wire.
If you're getting current from the hot terminal, you know the coil and box are good, then I'd suspect the little green coaxial cable that runs from the dist to the 6 pin harness.

You can use a voltmeter to check for a pulse while the car is cranking.

Elfer · 12:06 PM

Which one is the pulse generator wire? How do I check if the coil is good? When the ignition is on, where should I be checking if either the coil and the CD is good? Engine electrics is one of my weaker points and would just like to isolate the problem. Thanks guys.

emcon5 · emcon5's Garage

The green wire is the trigger from the distributor, aka pulse generator. From your description, it sounds like you have this coax (2 part) wire going to only one terminal on your CDI. It should go to 2 terminals, "31d" (outside) and "7" (center).

Seriousely, look at the wiring diagram. It shows exactly where everything needs to go.

Good luck,

Tom

Elfer · 12-07-2003, 09:25 PM

Thanks Tom. Well I triple checked the wiring connections and the green wire have both connections to the CD box properly conncected per diagram. I have the 6-pin harness to the CD so everything seems to be wired correctly but.....still no spark!

I am really stumped as I dont know where to move next as far as diagnosing the problem. The dizzy was never touched and the motor was running fine from the donor vehicle before it was taken out. So I know the motor is good and all electrics should be good as well. Just dont know what to do next. Please help if anyone wants to chime in. Thanks.

Superman · 12-07-2003, 09:32 PM

When you crank the engine, there should be a faint pulse coming across that green wire to the CD box. Very faint. A fraction of a volt.

We could just tell you that you probably have a bad CD box or something, but the simplest (cheapest) thing that might be wrong is that green wire. If you have the stuff, you could make a couple of single-conductor wires, with female "gaston" connectors at one end, and the very tiny connector at the other end (distributor end). The wire does not need to be coax, and if a good couple of wires makes the car run, then you found the problem. But, you'd need to have some of those teeny tiny distributor-end connectors, which are unusually small.

If your CD is getting the pulse signal, then keep checking various connections, including grounds. If a pulse is present, and the connections are good, then you can start suspecting your CD box and/or coil.

RoninLB · 12-08-2003, 02:59 AM

does anybody know if the 6pin/dizzy system spark can be triggered somehow like the points system does by removing the single dizzy wire and touching ground ?

Elfer · 12-08-2003, 11:47 AM

Ok, Ive got my tester, but where should I be putting the probes?
I told you guys that electrics is my weak point.

Shipibo · 12-08-2003, 01:28 PM

Do you have an alarm system that needs deactivating? Chuck

Elfer · 12-08-2003, 05:19 PM

Hi all. I have confirmed that there's an electrical pulse from the coaxial wires. The reading fluctuates as the motor is turned. I did notice that the coil has a small amount of fluid that oozed out of the connector and to the wire.
A couple of questions: Is the electrical pulse generated by the coil to the CD, or the opposite direction? Are there any tests that can be performed in order to find out if the CD and/or coil are defective.
Thanks.

filou · 12-09-2003, 04:04 PM

Before anything guys, let put me 2 cents !!!
Be extremely careful with that that CD box, don't try to pock around disconnecting and connecting wires because you have high voltage out of those wires and you can directly dommage that CD box if you put at wrong place. Get a diagram and check everything that way, first !!!
i don't mean to be a smart one here but don't fool around with Porsche equipment (if you don't mind beaucoup $$$ and wasted time).
take it easy,
truly, Phil.

Early_S_Man · 12-09-2003, 05:05 PM

Elf ...

The 600 Ohm pickup coil in the distributor generates the AC waveform as the 'star' [reluctor] passes by in close proximity.

Here is a thread where failure modes of the Bosch CDI unit are described:

What goes wrong with OEM CDI units?

If your car has the factory alarm system ... please read the following thread:

'82 SC Won't run

The following diagram may be of use:

Superman · 12-09-2003, 06:13 PM

Efficient. Complete. Elegant.

Elfer · 12-09-2003, 10:14 PM

Nice...Very Nice... Thanks for the diagram Warren, and thanks to everyone here on the board for helping out. Im going to try to sort this out this weekend. Ive been poking around the engine bay the last few days but its just too damn dim in my garage even with some pretty adequate lighting after 5:30 PM. I didnt even think about an alarm system, and dont even know if my car has one. Well, Ill post what my findings are when I figure all this out. Thanks again everyone!