<E30> No Spark

[Adrian North <anorth@xxxxxxxxxxxxxx>]

Might seem like a stupid question:
What can cause there to be no spark? The starter turns but the engine
won't catch.

For more info - The car's an '85 316 (carb engine) with 110,000 miles
(ish).
I've checked:
Spark plugs (were rather knackered, but changed them)
Plug leads & Coil Lead (replaced)
Distributor cap & Rotor arm (replaced)
I've checked primary & 2ndary resistance on the coil. Slightly out
compared to specs (1.1 ohm primary instead of 0.82 ohm, 1.8K instead of
2K secondary), but I'd guess that's okay! (?)
Impulse generator circuit seems to be working - Checked as in the Haynes
manual and all checks pass.
There's power from the coil to the distributor - checked there's a
voltage.
The carb control relay seems to work, but the voltages don't tie up
completely with what the Haynes manual says (terminal 20).
The same with the ECU connections - Terminal 20 is supposed to give 0.5
volts with the ignition on, but it gives 12 volts with ignition on or
off. Terminal 5 is supposed to do the same, but gives nothing. Other
terminals to check in the Haynes manual (Can't remember if it's the Carb
Manual or the 3-series manual) were okay.
Seems that there's something wrong with terminal 20!?

I've made sure the plug leads are in the correct order (1,3,4,2) and
tried them in all the positions around the distributor.

Anyway, just before this trouble, I'd taken the dashboard out the check
the SI Board batteries, as the Inspection light comes on within a week
of resetting. Would this cause any trouble? I wouldn't expect it to, but
I'm paranoid!

I'm (hoping to) getting it towed to a Friend's garage (300 miles away),
but he's a Porsche specialist, so any ideas would be VERY useful!!

Thanks!
Adrian
'85 316
Basingstoke, UK

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