914/6 Ignition Problems

[Stressless]

Over the last 10 years I have had a lot of problem with spark and the ignition electrical system. I had a factory race mechanic who worked on the 6's look at it in the past but he has since retired and moved away. We replaced the original Bosch CD with several Permatunes. I say several because the first one went bad. It ran for awhile and then the same problem, shut down just like someone tyrned off the key. Finally about 7 years ago we replaced the coil with a new Bosch and swapped the Marelli distributor for a Bosch. It has been working great until last year. Last spring the same problem returned. I unplugged the Permatune and hooked up the old Bosch CD unit and it ran great again but several weeks ago I drove to dinner and upon returning to the car it would not start. Finally after many attempts it did strart and got us home. After that it would start and run for about 2 minutes and shut down. I rehooked the Permatune but nothing. The Bosch unit gave out its' high pitch sound only occationally so I cleaned every connection throughout the engine bay including all grounds but still only got intermittent sound. I checked voltage at terminal B of the connector to the CD box and had battery voltage. I then checked the Bosch coil as per the factory manual and found 2.5 ohms between terminal 1 and 15 (spec is .4-.6) and 9,500 ohms between 1 and 4 (spec is 650-790). So I determine that the coil is bad and so is the CD box(es).

I really don't want to spend the $500 on a new Permatune CD and required new coil let alone the $1600+ for the Bosch set-up but I want it running. Is anyone else with me on the suspected problem or does anyone have another idea. I have been in contact with that factory mechanic but we are both baffeled as to why this keeps on happening. Do others have problems with these CD boxes like I do? It just runs so great when it will start! I hope this gets read and we can dust something off the forum. Thanks everyone! :D

[Loren]

Have you replaced the spark plug and coil wires?

Seems silly but my 76 S had a similar problem and I found that it would burn up the coil wire (inside). I would certainly check the resistance of each wire.

Might not hurt to check the engine ground strap too. Strange things happen when their is poor chassis ground on these cars.

[Stressless]

Thanks for the fast reply Loren :) All those wires were replaced with the expensive shielded type when we had all these problems to begin with but I will check them and the engine ground. Are you saying that the lack of high pitched sound from the Bosch CD box might be the cause of bad wires or it contributed to the demise of the box? The box should sound off even in a test bench condition, correct? Todd

[Loren]

Um... I am not sure I remember.

It may need a load for the high voltage.

[wvicary]

As Loren said check the ground from the transaxle to the frame. I know the 914/4 suffered from rubbish fuse blocks in the engine compartment, not sure about the 914/6 but it wouldn't hurt to check it out.

[70Sixter]

If under dash fuse block is the problem there is a new type fuse block available at 914club.com or 914World.com. Maybe both. Personally I'm trying to stay original.

The engine compartment block can suffer from corrosion and poor connections.

The ground sounds very plausible. Also check it in the dark for telltale shorts. I had that once and the blue arc was visible only in darkness.

[hanayaro]

What may be happening is that the system is receiving an invalid password from the Pass-Lock cylinder and the ECM will then shut off fuel. So what happens is that sometimes it will start and stall and other times it will just crank. Also check the distributor.