Ignition problem

[ChrisR]

I've just fitted an electronic conversion kit to my 1978 1.3 Marina. Along with new cap, plugs & leads. Now it starts first time, every time and revs nice and clean. But, after a minute or two of running, it refuses to rev and just sits there, barely at an idle. If I turn it off and wait a minute or so, it will start and rev normally again. After a minute or so, it does it again. I tried setting the timing and noticed that with the engine at 1000rpm, the strobe was perfect. But then, it would start to misfire and eventually drop to a lumpy tick over with the strobe light flashing very intermitantly. I'm sure it's an ignition fault. The kit I used states that you don't need to change your coil but perhaps I do. Any idea's would be much appreciated.
Thanks, Chris.

This is what I bought:

http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... 0328947595

[MarinaCoupe]

If you search back through the Technical Section, you'll find other people have reported similar problems, including me. I ended up reverting to points.

But I have formed some theories, which I have yet to prove and would value others views.

The magnetic type of triggers rely on magnets on the rotor head passing the sensor (Aldon etc.) which has a little coil inside which produces a voltage, which then fires the ignition coil.

Theory 1 - As the engine warms up, the distributor warms up, if the metal base plate of the trigger expands with the heat it moves it further away from the magnets. As the distance grows it reduces the effect on the coil within the sensor, which stops it from triggering the ignition coil.

The fix would be to adjust the sensor closer to the magnets to start with and perhaps mounting it on a non expanding medium, say plastic or circuit board material.

Theory 2 - As the engine warms up, the distributor warms up, if the base plate of the trigger absorbs the heat, the insulation of the coil inside the trigger breaks down and doesn't fire the ignition coil. You could test this by putting a voltmeter across the output leads from the sensor, where they connect to the ignition coil, if it's working properly the voltage should be pretty constant, if it isn't triggering properly then the voltage should only read when and if the trigger fires. Even better if you have access to an osciloscope you can watch the wave form and measure the voltage change to see whether it is sufficient to trigger the ignition coil.

The fix could be the similar to Theory 1, insulate the trigger from the baseplate in the distributor either by putting say waxed paper or plastic between the distributor baseplate and the mounting plate for the trigger, or ideally remounting the trigger on a non conducting medium.

Alternatively Theory 2 can be tested quite easily with some gasket paper or plastic sheet sandwiched between the trigger and the disributor baseplate.

Thoughts anyone?

[marinajohn]

I have had electronic ignition fitted to car since I owned it (over 2 years) and have no problems. I did fit a Lucus sports coil though.

[jiversteve]

From first reading I was thinking fuel starvation or airlock vapourisation but if the fuel system has not been changed.....

Electronic ignitions do put a greater load on the coil as the electrical switching is far more consistant than points. It may just be that your coil is marginal, check that it is OK and not overheating. Around 3 ohms should be fine.

Chris is right about some of the heat issues, worth noting that the ebay seller did say *Applying a high quality silicon compound (e.g. Dow Corning MS4) to the base of the module and metal plate is advised prior to fitting within the distributor* This will help with thermal conductivity, but if an insulating compound is used may compromise earthing.

I have used such a system in my Marlin, Marina 1.8 powered, that is notoriously prone to overheating due to small radiators and tight engine bay, with no problems.

Some of the problems reported have been due to poor earthing through the distributor.

From another web site: -
Make sure there is a good and proper earth between the Ignitor pick-up and the block - so that includes no dirt/grease between the pick-up and base plate, no thread-lock compound on the pick-up to base plate screw, a good earth between the sliding plates where a vacuum advance is used, a proper fixing where a vacuum unit is removed to fix the two plates together, clean base plate to dizzy body screws, clean dizzy clamp to retaining bolts fixing, and clean retaining bolts to block fixings. Apparently these units are very sensitive to poor earthing.

Have you consulted the ebay seller, he might have a solution.

[Number 63]

From my sketchy memories of working on points systems, they are voltage limited to prevent burning of the contacts to around 10 volts. This is done either by a high resistance feed wire or the ballast resistor. To aid starting, the points are fed with 12 volts for a minute or so until the resistive wire heats up and knocks the voltage down to 10 volts. The ballast resistor works in the same way. If you have either of these devices in the modified circuit, it could be reducing the voltage after a minute or so and giving a weak signal to the coil...

[ChrisR]

Thanks to all who have made suggestions. I will have another look at it in the morning and check all the earth wires are good.

[Kilroy]

Chris
There is another angle.
Do you have any form of suppression fitted.?
Either suppressor leads, or caps, or 'R' type plugs.?
Some electronic ignitions require at least one form of suppression. Without it, the RF interference given off by the unsuppressed spark can confuse the chip, and cause it to shut down. A restart usually has everything back to normal, until reaching the same point again.
Failing that I would suggest changing coils first - because it is simple, and noting that if you have a ballast resistor in circuit, then you need a 6 volt coil - sometimes labelled as 12 volt with ballast resistor - if you are now running without a ballast resistor (or never had one), then you definitely need a true 12 volt coil.

Kil

[stuthegasman]

do these work for itals as well ??

[ice man]

I have bought the same kit for my car, and also a Lucas DLB105 sports coil ...

Actually mine came with a new improved module ...

http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... %26ps%3D42

My kit said 'now with high quality silicone compound and has a small sachet of white 'stuff' with it. and is supposed to be more heat resistant and more reliable.

I plan to fit the module first, then when it is all running and I've done a few miles, change the coil and open the plugs up to 0.035"

I have to agree with all of the above, maybe the coil is on its way, as these electronic ignitions are supposed to allow the coil to deliver twice the energy than when points are fitted...

Also there may be a heat issue, although if it is based on time rather than temperature then the coil losing charge faster than it can be replaced sounds plausable.

I'll post how my test drive goes after I fit mine on the weekend.

It might be worth buying the later module for the cheap price, or better still get a proper Magnetronic, Pertronix or Aldon kit instead, 4x the price but much higher quality confidence...

[ChrisR]

Still the same. I ran it for about 5mins in the drive to warm up and then took it down the road for a trail. Within a mile or so it came to a halt. It just barely keeps a tickover but will not rev. Turn it off and wait two mins and off it goes - for about 100 yards. I'm going to change the coil.

[stuthegasman]

sounds like fuel starvation to me uses up what's in the float chamber then runs dry I would check the condition of the fuel pipes and check the filter on the end of the sender in the tank, I had the same problem with my 1800 coupe when I first got it after it was off the road 15 yrs, it would run all day at idle but take it down the road it would run ok for a minute or so then start spluttering if I pulled over and let it tick over I could set off again, sometimes it used to cut out all together if I waited 5 mins it would start and run again and repeat the problems again, a new fuel hose and I removed the sender from the tank and cleaned the filter and it's been ok ever since, one way you could prove if it's fuel starvation is to carefully secure a petrol can somewhere under the bonnet or on the passenger floor and run a piece of hose and connect it to the fuel pump give it a run and see what happens, just a thought

[ice man]

I installed my electronic ignition (newer type with a red pick up) and I couldn't beleive how easy it was.

Anyhow, on the original coil it was fine so I put in a Lucas Sport DLB105 coil and that too was fine, retarded it back a touch and there have been no problems all day. starts on the first compression stroke every time now, no more cranking...

Could be fuel but i doubt it, especially if it re starts fisrt turn. if it were fuel starvation a fair few engine cranks would be required to refill the float chamber, unless you have an electric fuel pump? Plus you say the strobe starts to flash intermittently...

Try either putting the points back in or a new coil...

[ChrisR]

Latest update: I replaced the electronic unit with some new points, condensor and rotor and now the motor runs like a sewing machine! The unit I had must have been faulty??

Thanks to all who offered their help.

Chris.

[jiversteve]

Thats good.
I wonder what the prob was with the electronic gismo. Its a shame because so many people have found them to be excellent.
Did you get back in touch with the ebay seller?

[ChrisR]

Not yet but I will do.