Guys I'm having problems with this unit with the earth eyelet on one of the mounting bolts.
it is loose but when I try to tighten it the motor cuts out and won't start until I loosen and wiggle it around.
The wire doesn't appear to go anywhere. The other 2 wires in the same loom go to the distributor Pick-up ring. But the earth wire doesn't come out the other end, only the eyelet end with the mountains bolt.
My questions are. What is the unit, where should that earth lead go to and can it be earthed to another location?
Cheers
It is mounted on the front top in front of the radiator.

 

Ok after doing some research iv found that the mystery unit (to me) is the ignition amplifier.
the lead and earth eyelet I am having issues with from what I can gather is a shielded loop. I don't quite understand how it all works but does it make a difference whether the eyelet is grounded on the existing bolt through the amplifier or can I make a nice new clean ground for it on the front radiator mounting? Is there a possibility that this shielded loop is damaged and is there a way to rectify it? I have read a few posts by Grant who states that the shielded co- axial goes to the ECU in the boot but I cant see the wire going further than the 2 wire connector going to the distributor Pick-up ring. Mine is the straight six 3.6 model so may differ from the V12?
Cheers

 

It might be that the bolt IS the ground for the body of the ignition amp and when you loosen it while the car is running, interrupting the ground, it's shutting things down...?

It might also be that the wire and eyelet was someone in there before you, jumping a piggy back ride on that bolt as ground source? I'm just throwing these ideas out there as I can't see the stuff in the pic so well...

 

It's the other way round. The eyelet is loose and car runs. It's when I tighten the bolt the car shuts off which I find bizzare. Ide like to make a fresh ground but not sure if it can only be grounded on the amplifier housing.

 

You know what (as if ya haven't already),,,,

scratch everything I typed/said - I don't think it makes NO sense, lol... I don't know enough about this system and more, didn't read what ya wrote carefully enough...

 

It doesn't matter. It's the suggestion that matters. All input is very welcome. A learning curve for all.

 

Well, on that note, lol...

How about this. There is something corrupting the ground? Could it be that somehow there is a very small amount of voltage coming into the shield somehow somewhere?

 

Could be a possibility. I'll check if there's voltage on the shield and the eyelet. Maybe tightening the bolt down is pressing the case against a voltage source inside the case.....easy to verify.

 

The eyelet is probably just a shield wire to protect the two other signal wires picking up electrical noise from the high voltage on the 6 plugs.
Normally you connect the shield wire to an earth point on one end only, via the eyelet.
If it is not connected to an earth point the ignition system will still work but be vulnerable to noise.
If your engine stops running when you earth the eyelet that suggests one of the signal wires is touching the shield somewhere.
So when you earth the eyelet you also earth a signal wire and that stops the ignition system working.

 

I totally understand your logic and agree with you.
What's confusing is that the shield wire is earthed to the amplifier casing but tightened to a point that with a little bit of of a push it will move. And the car starts and runs at that. But if I tighten the bolt half a millimeter the car shuts off and won't start until I loosen to a similar setting. So I might try earthing to a separate location. And if that doesn't resolve the issue then I'll strip back the outer wire and look for a short in the signal wires. What would be the best shielding to use if I redo the wiring? TV coaxial shielding?

 

That does sound odd.
Without being there to investigate further I have no answer.
TV coax is not the best answer because you need two wires for the ignition.
If you can find an electronics hobby shop, or maybe a shop that repairs TVs etc., you can find twin shielded wire which is ideal.
Bear in mind it is about 99% certain the wire is made in China and made at the cheapest price. It might not stand up to heat in the long term but should be OK for a few years.

 

You said it better than I ever could... Cool
I think there's a possibility that somewhere in the loom/harness - as Richard suggested - the signal wires are chaffed and touching... Might have to open it up and investigate.