Stunned Monkey wrote:I have spare ignition amps but in my experience, they are extremely reliable - I've never seen or heard of one fail.
The ballast resistor will get extremely hot under normal operation - it's there as a current limiter to the coil which -is- essentially a short circuit. You're looking at another red herring there. It's definitely worth re-crimping and replacing connectors on the ballast reistor and coil.
HAVE YOU CHECKED THE DISTRIBUTOR PICKUP? It's an electronic ignitinon system and these are known for failing, or it could be a simple cruddy connector on the yellow 2-pin plug. The rev counter doesn't move when cranking so (on a DeLorean at least which drives the rev counter from coil -ve) that'd rule out the coil as being the problem.
Hi Martin
Thanks for your input and the offer of the ign unit. I agree with you that usually that unit is normally very robust. However I really would like to rule it out. Not too sure about resistor being a "limiter to the coil which is essentially a short cct" My understanding of these ballast resistors, is this. You start off with lets say a 10v coil, you put a resistor in series with it, which drops 2v across it when normal running current is passing through it. Now car is a 12v beast, so under normal running with the resistor in place, the coil has 10v across it for which it was deigned for.
Now if you look at the cct, you will see a wire coming from the starter to the coil essentially bypassing the resistor. When you go to start the car, due to the heavy current drain of the starter, the voltage at the coil will drop, now here you are wanting to get the best spark for the engin to fire and we lack a full voltage across the coil. Now as the coil produces the EHT voltage in proportion to the ratio between the low tension winding interwound to the high tension winding, we end up with a low spark voltage, which in this example would be about 20% in round figures. So what we want now to produce the best spark, is to put 10v across the 10v coil. Now the starter should have 12v across it but no it will be down due to the heavy current drain by the starter, could be around 10v, so lets feed that 10v direct to the coil, but only when the starter is turning. That is where the lead coming from the starter to the coil comes in. Even if it slightly higher than 10v, you will get a slightly enhanced Spark voltage, but as it is only for a few seconds at a time the coil wont mind, so hey presto we have our full EHT spark voltage
In this example the actual values on the car are most likely to be different, but the principle remains.
We have not checked the pick up lead you mentioned, though I would have thought the AA man would have, however I would be worth checking again. Over to you John, lead going to a connector into the body of the disrtibutor. This of course is turbobob,s suggestion as well so we must check.
One little piece of info here for those that dont know, sorry to those that do. No connections on the coil the EHT one or the other two, have any connection to the body of the coil. It is a series component, ie:- Volts in (yellow lead) The other screw terminal is trigger in, ie:- some form of AC voltage (transformers or coils cant work on a DC alone) and the final output is the EHT to distributor. One end of each of the coils are connected together and go to the trigger input connector. A coil will work dangling in mid air not attached to the body of the car (This was a piece of useless information for you) With regard to the last paragraph re the rev counter, sometimes when the key switch is in the start position, it breaks the 12v supply to the instrument panel to stop the instruments jumping around due to the fluctation of voltage as each compression occures. Modern electronics dont like that.
I hope John takes up the offer of the electronic unit from you, as it would either solve or eliminate it from our endeavors.
John
1990 GTA Atmo, 2003 Jaguar X type 2.5SE Auto, 2018 Kia Picanto GT-Line-S 1.25
But I was passing my friendly Renaul Garage earlier, coil for the GTA D500 (ours) are priced at £50.75, they think it will have to come from France though. If I remember rightly either you or Lee thought the one fitted now did not appear to be the original, if this is the case, might be the reason why it went. Personally I would fit the Alp one, but someone out there might know of another, possibly a R25 one, which might be a bit cheaper. My man at our garage thinks that coils are normally around £30. But lets see if anyone can throw some light on the sublect. Any offers out there 
