Persistent misfire.

[DJT]

Could be the 3-wire connector as suggested above. Replace with a waterproof connector; plenty available on eBay and elsewhere.

Also suggest retard the ignition to 12 or 14 degrees. 20 is too far advanced.

[Ian Osprey]

I've thrown my multimeter out the pram!!

Timing set at 12 degrees. Still misfiring
Wires disconnected from Coil Ignition on
Yellow wire from starter measures 12v when engine turned over 0 otherwise
?? Yellow/Pink wire (resistor) measures 12v between the wire and earth
Brown to Luminition 0v
White/slate to rev counter 0v
Wires connected to Coil Ignition on
+ Terminal(Yellow and Yellow/Pink) measures 6v between the post and earth
- Terminal (Brown and White/slate) measures 1v between the post and earth
Engine running
+ Terminal(Yellow and Yellow/Pink) measures 9.5v between the post and earth

Think I need a new meter

[marshman]

I think I am correct in saying that the Lumenition systems uses an optical sensor and "chopper" in the distributor. If this is the case then have you checked that the "chopper" wheel is OK?, and also that the optical sensor is clean? Just a suggestion as the voltages you are reading around the coil seem OK - if they were the problem I think you would have more than a misfire. Also did you check the 3 pin connector between the distributor and the Lumenition as suggested by Davidf in post #13? Quite a few people have found this to be the cause of elusive ignition problems.

Roger

[Ian Osprey]

Yes Rodger, optical with chopper. There's no immediately obvious problem with the IR kit or the interruptor.
I have ordered a modern 3 pin auto connector to replace the original. It's a taped up mess at the moment. It'll be easier to rewire if I remove the module from the distributor, at which point I'll look more closely at what you suggest

[wilf]

All 8 blades on the "chopper" still there? They have been known to fracture with age and lose one or two.

[davidf]

"It's a taped up mess at the moment"

That could be a good clue as to where to look first!!!

[v8ken]

These might be useful-

https://rimmerbros.com/ItemFiles/Manuals/CEM_installation.pdf

https://www.merlinmotorsport.co.uk/f...tronicinst.pdf
Although my problem was a faulty(quite new)coil,but fault finding info' was useful,after also replacing my faulty multimeter.
Good luck ,Ken.

[Ritchie6]

I think I am correct in saying that the Lumenition systems uses an optical sensor and "chopper" in the distributor. If this is the case then have you checked that the "chopper" wheel is OK?, and also that the optical sensor is clean?

Roger

Just a quick related question if I may ask impose. Does the Lumenition system require any maintenance or cleaning? My Stag was fitted with one by the previous owner a good few years ago and unlike the old points which could be inspected for wear I sometimes wonder if it will just suddenly pack up one day.

Richard

[DJT]

Not really, Richard. It is still necessary to remove the distributor cap occasionally to check for wear, etc. so using a cotton bud to wipe the optical sensor clean whilst in there makes sense. Also check the 3-wire connector as mentioned above as these can cause problems. Other than that, forget about it. They last for many years without trouble. Having the power module mounted inside the car, away from engine heat, may extend the life.

[Ritchie6]

Not really, Richard. It is still necessary to remove the distributor cap occasionally to check for wear, etc. so using a cotton bud to wipe the optical sensor clean whilst in there makes sense. Also check the 3-wire connector as mentioned above as these can cause problems. Other than that, forget about it. They last for many years without trouble. Having the power module mounted inside the car, away from engine heat, may extend the life.

Many thanks for the info DJT. I'll cast an eye over it next time it's out of the garage. I was brought up old school with points and condensers.

Richard

[Lingen]

Richard.
It may not be necessary to do much to the Lumenition kit, but it is still advisable to take the rotor arm off occasionally, and put a few drops of thin oil under it to lubricate the mechanical advance/retard assembly. This was usually a job to do when checking the points, but when you haven't got any......
Mike.

[Ritchie6]

I always use to put a tiny dab of grease on the heel of the rotor arm as well. I bought one of LD parts green rotor arms as a spare when I bought the car because a mate of mine said the old ones can be troublesome as they get older due to a change in the plastic which makes them conduct the power away to earth (or something like that).

Thanks for the info and apologies for hijacking this thread but it seemed to be relevant and might help others.

Richard

[Ian Osprey]

I got a response from technical support at Autocar Electrical,the people behind Lumenition products.
The +1V on the -ve side of the coil during the equivalent of points open, is correct and required by the system.
I was also sent a PDF of a technical bulletin which list some diagnostic techniques if you think your system is on the blink. I was asked to acknowledge their copyright, and to provide a link to their website.

http://autocar-electrical.co.uk

TB17-Optronic-Ignition-Check-V1.pdf

[Ian Osprey]

I also need to say that the car is now running much better, still running way too rich, but I was able to take the car out for a run for the first time in many weeks.
Deciding to start afresh, I took all your suggestions, listed them in order of time and cost to do, went out to the garage and started.
No1 - Check plug leads are in the correct firing order
oh dear #3 and #5 were transposed.

I will be replacing the connections to the Lumenition as a matter of course once the new plugs arrive.

Many thanks for all your help and suggestions.

[Ian F]

Glad you’re getting it sorted Ian, enjoy!

ian F