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MG Midget and Sprite Technical - Optronic Problems

Hello All,

I've had ignition problems over the last week, with the engine running perfectly for a while and then cutting out suddenly. Sometimes it starts again straight away, runs for a couple more minutes and then cuts out. Sometimes it needs to be left a few minutes and then starts. It will run for 5 or 6 miles when cold before this behaviour starts, but once this faulty condition's arisen, your guess is as good as mine as to how long she'll run for.

During the 'won't start' episodes there's no spark, as proven by my strobe, but a solid 13V to the coil even at the point it dies.

I've put in new plugs and a spare coil I had lying around and that's not made it any better. I don't have a set of points lying around so I've ordered them, which will prove whether it's the optronic at fault.

Does anyone have any insight into this problem, and/or does anyone have any experience of repairing Optronic modules, or know of anyone I could send it to for a seeing to?

Thanks
Mark
MarkH1

Here's a test for ignition systems, this is for points, but your module should test the same because it is after all an electronic points replacement (if that makes any sense?)

Do the test when it quits & you have no spark...

http://www.midgetregister.com/index.php?option=com_content&view=article&id=73&Itemid=66

Good Luck

Dave :)

Dave Rhine ('78 1500)

Great link Dave
Robert (Bob) Midget Turbo

connect the timing light to the ht lead from the dizzy to the coil and check if you lose spark there as well.

I have more or less the same with my crane fireball ign. Not sure if my trouble isn't / wasn't caused by the rotorarm. Keep us posted!
a.o. arnold

Yes, Robert, it is good...forgot where I how found it now, but lots of good info.

There've been a lot of defective NEW rotor arms floating around lately, especially here in the States...got one last Summer & the little beast wouldn't run right after a fresh tune up...electrickery!

Dave

;)
Dave Rhine ('78 1500)

Thanks for the link Dave, there's loads of good info there. I'm running one of the Distributor Doctor's red rotor arms, and just to be sure have tried a spare with no change,
Arnold there is no spark at the king lead either.

I've just found Lumenition's helpful ignition testing bulletin:

http://www.newtronic.co.uk/new/support/lumign/optron/TB17OptronicIgnitionCheck.pdf

Here's the bit that applies to me:

"There is a possibility that the optical switch is failing. If it is there will be a very definite pattern to the
intermittency which will be as follows:
· The ignition system works perfectly when the engine is cold but misfires or stalls as the
optical switch is heated by the rising engine temperature. If the engine is stopped and left to
cool for a few minutes (also cooling the optical switch) the engine will start and run perfectly
but fail again a few minutes later when the distributor re-heats the optical switch – and so on."

Which absolutely accurately describes what I'm experiencing. So there's little doubt in my mind that the optical sensor is at fault.
Points arrived today, so I'll put them back in and fully expect everything to run beautifully.

anyone have a spare optronic optical switch for sale?

Mark
MarkH1

Friend's TR-6 had the 'bulb' fail suddenly on his Luminition system. Looked very complicated to me, with bulb/sensor/wheel and separate unit, compared with Ignitor.

Also - the bottom plate was a Luminition design, so not easy to switch back to points as PO did not include original plate with the car.

All-in-all... not a system I'd want in my car.

A
Anthony Cutler

I have had very good experiences with Lumenition Optronic.

One thing to check is that the three way plug is connecting properly - it may even be worth re-making the connections before condemning the whole system.
Dave O'Neill 2

Mark, I use the Crane XR700 (also optical), in my case the car started missing after 15 minutes, but didn't stall, unless I went on driving. Car runs on 3 and later on on only 2 cylinders. In the end it would stop and leaving it for 10 minutes it would run on 3-4 cyl...

What about your case?
a.o. arnold


Arnold - the symptom I have is just a very sudden and complete cut out, from running perfectly to no spark at all. It's then a will-it, won't-it lottery as to whether it will run again and if it does for how long...

Ant - the swap back to points is very easy, the chopper just pulls off and the optical unit literally takes the place of the points held in by the same screw. It's a quick and easy swap. Will only take a couple of minutes to do.

Dave - I've tried 'adjusting' the three way plug to make the connections snugger (is that a word?) with no change, and I think the description in the bulletin so closely match my experience that there's little doubt in my mind...
MarkH1

>>Ant - the swap back to points is very easy, the chopper just pulls off and the optical unit literally takes the place of the points held in by the same screw. It's a quick and easy swap.

My friend's must have been an earlier one... def no way to retro-fit points (a strong consideration for any elec ign system...)

A
Anthony Cutler

Ok, so that is a bit different from my failure. I fitted a new cap (old one I could turn two of the connectors) and a new rotorarm (I had a very old one), drove around for 15-20 minutes, no real missing. In my case it is as if it is worse when it is warm outside..... and worse if I drive it hard(er).

a.o. arnold

I'd consider a Hall Effect trigger system, such as a pertronix unit.

Completely reliable...
Dave Rhine ('78 1500)

My Magnetronic just fried on me, now looking at a full accu spark dizzy.
mgdan2

Mark, any progress on your side?

I nenewed cap and rotor, have been driving for 20-25 minutes, no missing. But I am not fully sure it is solved yet.

In earlier events outside temperature also seemed to be relevant (warmer outside made everything a lot worse).

a.o. arnold

I switched back to points and re-timed on Saturday morning.

The complete task took me 55mins including my manlab 5min 'schoolboy error' penalty for forgetting to put the rotor arm back on the first time I tried to start her up. I test drove a 40 mile test drive, and have done 3 more trips of about 15 miles each since. Everything is working perfectly. So, it's the optical switch which is defunct. It's running well on points now, so I'll keep it that way while I decide whether to replace the optical switch or buy a SimonBBC hall-effect system and flog the power module.
So, Arnold it looks like I've solved my problem - good luck in solving yours.


PS. Modern cars are full of sensors, both optical and hall-effect. I wonder how many of them will start failing in 20yrs time???
MarkH1

Good to hear Mark

I am not convinced myself whether the new rotor arm and cap are the sollution. I have to take the car out for a linger trip to be sure.... to be continued

PS I've been stranded for several times now and fear the linger trips...no fun to stop in the middle of a fast lane.....
a.o. arnold

This thread was discussed between 07/11/2010 and 16/11/2010

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