Engine suddenly cut off when idling

[jonwat]

3 hours ago, andydclements said:

a 12v coil is in reality a 6v coil. With a ballast (resistor) system the coil normally gets 6v and the ballast gets 6v by wiring in series, then when cranking the coil gets a supply directly from the supply which will drop to c10v so that the coil doesn't get too little supply. Non-ballast system just gets battery supply in either situation.

Thanks for that Andy, could you also drop a line to my father's mother detailing the extraction of the contents of an oval object laid by a female bird? 😂

[andydclements]

Well John, it was following a post that seemed to indicate that the part wasn't suitable, so seemed entirely necessary to correct that.

[Clive59]

I use this, works perfectly with ballast system. Mine is just an N/A 912

https://simonbbc.com/viper-dry-ignition-coil-sports-ballast/

 

[hspeck]

Thanks... 

I didn't know the 912 NA was a ballast system, as I could not find the ballast

I have a new coil from SJ. It is the Lucas Dlb198. That is also for a non ballast system.. Hence the confusion too... 

[ekwan]

You may never find it. It's part of the wiring. 😂

[hspeck]

I see ... so they use the wires to act as a ballast .... any idea which wire is that?

[ekwan]

Why does it matter which wire it is. Just use a coil meant for a ballasted system if you feel the need to swap the coil out. 

[hspeck]

1 hour ago, ekwan said:

Why does it matter which wire it is. Just use a coil meant for a ballasted system if you feel the need to swap the coil out. 

because it will be good to know, especially if we need to rewire the system in the future

[910Esprit]

If you have Lucas constant energy, I don't think its a ballasted system -  (clue may be in name of the 'CE' system).   DLB198 coil sounds correct to me.   NB my 84 turbo still has the yellow/white lead from the starter to bypass the ballast, but its not used.    Looking at the wiring diagram it was deleted after the move away from Lumrenition

[hspeck]

Thanks, I will still need to look through the wiring from the ignition to the coil and the ignition system as the fault is intermittent.

If the wires tested ok I will need to start replacing the components one at a time

[jonwat]

4 hours ago, hspeck said:

I see ... so they use the wires to act as a ballast .... any idea which wire is that?

It's normally a braided wire, not the usual plastic covered.

Lot's of people don't know about ballast ignitions & think a coil is a coil, not realising they need a 6 volt one. 

[ekwan]

1 hour ago, jonwat said:

It's normally a braided wire, not the usual plastic covered.

Lot's of people don't know about ballast ignitions & think a coil is a coil, not realising they need a 6 volt one. 

But the million dollar question still needs an answer.......ballast or no ballast. 😜

[hspeck]

According to the service manual, the coil does not require a ballast... 

Should remind myself to read more carefully in future 

[ekwan]

I could have told you that by asking you to check how many wires run between the distributor and ignition amplifier. But since you think I am a troll..........😎

[hspeck]

Well... You didn't did you? 

Anyway, it doesn't matter whether you did or did not, most important is now I know... 

[Clive59]

22 hours ago, hspeck said:

Thanks... 

I didn't know the 912 NA was a ballast system, as I could not find the ballast

I have a new coil from SJ. It is the Lucas Dlb198. That is also for a non ballast system.. Hence the confusion too... 

Umm, sorry, mine is an Elite S2.2 912, apologies for confusing things.

[hspeck]

7 hours ago, Clive59 said:

Umm, sorry, mine is an Elite S2.2 912, apologies for confusing things.

no worries... we are all learning  ... cheers

[hspeck]

An update to this.. 

So today I tried to trace the various wires from the harness, and it was really a mess. 

I tried to replicate the effect by 1st removing the fuel pump relay and fuel pump fuse but the engine did not die in both instances. I am not sure how pulling the relay and the fuse will affect the fuel pump function, and it apparent has no effect. 

I then removed the pick up wire from the amplifier to the distributor, and the engine died immediately, very much like what happened the few times when I encountered the engine dying. I remove the different connections at teh coil and the effect was the same. 

Does this mean it was an ignition issue? I am still unsure. 

I also opened up the amplifier and all the components seems fine, although I did realised that the actual amplifier was not a GM1178813, but another GM number. Unfortunately I forgot to take a photo of the amp. 

Whilst doing these, I noticed that there was some sort of oil on the coil, and there was an obvious patch on the surface of the ignition box. So I replaced the coil. 

I let the car run for about 20-25mins with the new coil, and tried to wiggle the various wires, but nothing I did kill the engine. 

I will need to drive the car for a few days, and hopefully will know if the coil was the culprit. 

Also, I am thinking to redo the wires from the harness to the relay sockets, as they are running over and across each other. 

Crossing my fingers it was a bad coil. 

[jonwat]

34 minutes ago, hspeck said:

I tried to replicate the effect by 1st removing the fuel pump relay and fuel pump fuse but the engine did not die in both instances. I am not sure how pulling the relay and the fuse will affect the fuel pump function, and it apparent has no effect. 

The engine would continue to run until the fuel in the float chambers was used up.

The oil on the coil does sound as if it was faulty but would not cause an instant stoppage, that would have been more like a bad connection. 

Sounds like you're getting there. 

[hspeck]

So it's been 1 week since I replaced the coil, and the car has yet to do on me.. Crossing my fingers somehow it was because of the eh coil, although I still do not understand how a leaky coil can have this effect... 

Thanks all for the many advises

[ekwan]

A leaking coil overheats. The oil is for cooling. 

[drdoom]

As observed by Eric the oil is for cooling. Perhaps with that gone heat could build to the point where internal wiring shorts it out?

[jonwat]

I'd have thought it would have been misfiring long before that, whenever I've hade a coil on the way out that's the first symptoms.

[Andyww]

If the coil was a type which required a ballast but there was not one fitted, it would have overheated. This results in oil seepage and the internal thermal cutout in the coil tripping out, until the coil cools down again. This causes intermittent sudden engine stops especially when stationary, no cooling air over the coil.

 

[ekwan]

9 hours ago, jonwat said:

I'd have thought it would have been misfiring long before that, whenever I've hade a coil on the way out that's the first symptoms.

Coil resistance builds up as the wiring heats up. That's why they (coil) work again as it cools down.