924Board.org

[maybeoneday]

This is what I did, mine is more like a amp neg cable. As long as it is shielded and at least as thick or even better thicker than what was there.

[img] http://s899.photobucket.com/user/adrianlamande/media/pic1_zpshbjqg7id.jpg.html [/img]
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1977 924 NA Auto

[Talby]

So I got back from work about an hour ago and did some thinking.

Realizing that I forgot to check the resistance on the lead from the coil to the rotor I immediately attacked it with the multimeter and found a resistance of 2.25kOhms. I'm not certain but is that too high? I measured the lead on my dad's triumph spitfire and got a reading of 680 Ohms but it uses a points system.

Can anyone check this resistance on their vehicle and give me the results? I would be grateful.
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"The phoenix asteroids..."

[maybeoneday]

just measured mine on a brand new lead and got 1.2k ohms, Top Gun leads, spiral core 7mm.
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1977 924 NA Auto

[Lefty]

I know, I bought a set of the top gun leads, they are crap, car ran rough. Bought a new set of Bosch leads, runs like a dream.
Just be sure you by the correct bosch leads there are a few different part number.
Cheers,
Lefty
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One less beige car

[fiat22turbo]

You can also use generic replacement leads and resistor plugs to avoid the extra costs associated with the Porsche leads with their built-in resistors.
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Stefan
1979 924 Carrera GTS (clone-ish)
1988 944 Turbo S (Silver Rose)

[Talby]

Well, I tried using a different lead from the coil to the distributor and I still cannot get any spark. As I said before when attaching a spark plug to the coil lead and a ground it will spark when turning the key from the 'on' position to 'off' but will not when actually turning over the engine at the 'start' position.

I am beginning to fear that the Transistorized Ignition Unit is to blame.

Heres a photo with the guts showing of my ignition control unit (left) and a spare I had laying around (right).






Obviously the left one has had some water damage and is fubar but is there a way to test its functionality directly? I could not find anyting in my shop manual but if there is a way i can test its output or something it would be nice since these run around 400 bucks new.

Any alternatives? MSD?
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"The phoenix asteroids..."

[maybeoneday]

From memory (I have seen a few Bosch boxes while looking for my ignition parts) they are not expensive. There are also other options of which MSD seems a bit like overkill on a road car. But do some research, I have only ever used the UK product called accuspark on a combi and 914, and my 924 appears to have a hotspark module installed but none of these cars have have a transistorised setup and I am thinking the hotspark may be the cause of my grief. Do some research surely there is a nice option not too expensive.
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1977 924 NA Auto

[musicalannette]

hi.
having no spark is a problem.
t
he melted wires near the exhaust manifold might cause you problems later on when up and running, maybe the wiring is less of a problem as your car is left hand drive? but when the car is working ok, i would replace the wired down to the starter and alternator(the thinner ones, not the very heavy current ones) with p.t.f.e. insulated wire.its not cheap, but it wont melt unless it rubs on the exhaust.

as for the no spark, the coil should have 12volts to the + of the coil, then to make a spark the - side of the coil is connected to ground/earth and then connection is broken to make the spark. this is probably whats happening with the key switch.

the box effectively connects the coil to ground then breaks it. yes you could test them, but you would need to make a test bench and tbh if you are struggling to make the spark work you will probably really struggle to set up a test rig.

what you have to remember is thet the box is making the - of the coil go from ground to open circuit. but only while the engine is running. if you measure with the meter while you crank it might read 5volts. this is because the internal sampling of the meter is a bit slow, it really might 10 then 0 then 10 then 0 and the meter comes out with 5. instead just crank a little and see if you can see the 12ish then 0 then 12ish then 0 but only bit by bit by letting the starter turn for a very small time.

if this is ok then just plug a spark lead and plug straight to the coil and you should get a spark, if you do see a spark the coil is good too.

then its through the cap and rotor arm in the dizzy.so there next to check.

a word on the boxes, unless you are lucky enough to have something burned out (it will look black and charred) then the only real way to check those boxes out is with a more complicated meter.there is a circiut diagram on here, but try taking the dizzy the coil and the box to a tv repair shop, along with the ht leads and a plug.

it really isnt easy to walk thru it on the board.
http://www.924board.org/viewtopic.php?t=36526&highlight=ignition

about ballast resistors, the coil should be fed battery volts whilst cranking then is fed thru the resistor when the engine is running. modern coills are either on the plug or sometimes are good enough they dont need them, if you leave it off the coil could get warm or hot and burn out. a v8 coil will probably be ok without it. i think the coil is a bosche, the usually have a orangeish colour on the top.

hope this helos.
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I KNEW white wall tyres were invented by Americans .....just not at Boeing.... to be fitted on the 737.....

[gti69]

Hi guys. Was there any update on this issue? I have exactly the same symptoms on my 1981 924 N/A. I have sourced two good transistorised units to check if this fixes it but this did not resolve the problem. I also have a spark at the turn of the key but none when cranking. Car was working fine before placed in storage 5 years ago.

I started looking into pick-up coil replacement. Maybe this is the culprit?

Cheers,
Tom
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Tom
VW SCIROCCO GT2 '92 - 95 BHP - LHD
VW SCIROCCO GTX '84 - 112BHP - RHD
VW SCIROCCO MK1 '78 - ??? BHP - LHD
PORSCHE 924 '81 - 125 BHP - LHD

RIP VW SCIROCCO Scala '91