Betty the Oval - Donovan D - ex-MINCE

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Donovan D
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Re: Betty the Oval - Donovan D - ex-MINCE

Post by Donovan D »

Dawie wrote: Mon May 31, 2021 10:16 am If feed to ign coil is indirect... (As via relay, ecu, etc).

This can happen. There is a tiny current via alt light which keeps relay or electronic switch energized. Normally if switched ign power directly feeds coil, this small current is inadequate to continue sparking.

Try a diode in series with blue wire to alternator. Marking on diode should face towards alternator side.

Correct, the feed to ecu is via relay.
Will give it a go. Will a 1N5821 also do the trick ? I do have them in the garage.

Thanks Dawie.


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Re: Betty the Oval - Donovan D - ex-MINCE

Post by Dawie »

That should also work.
Do'nt assume anything- (While doing fault-finding).
"Things should be as simple as possible, BUT NO SIMPLER THAN THAT."
"If something can go wrong, it will go wrong" (Murphy's law).
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Re: Betty the Oval - Donovan D - ex-MINCE

Post by Bugger »

This Project is nearing the goal Post :hangloose:
Adapterplates Available for Rotary in Beetle and others aswell
And Special Boxes built for Rotary Conversions and Scubies
Pierre
082 600 8663

CLick on Banner Below to be routed to the Web site

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Donovan D
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Re: Betty the Oval - Donovan D - ex-MINCE

Post by Donovan D »

Dawie wrote: Mon May 31, 2021 12:12 pm That should also work.
Thanks Dawie !!!
It appears that the diode did the trick, the engine shuts off with ignition and does not keep on running.
This was a real head scratcher
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Re: Betty the Oval - Donovan D - ex-MINCE

Post by acpaterson »

But, weird you needed to add this diode to make the car work how it should. Means there's something wrong somewhere else no?
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Donovan D
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Re: Betty the Oval - Donovan D - ex-MINCE

Post by Donovan D »

acpaterson wrote: Thu Jun 03, 2021 10:40 am But, weird you needed to add this diode to make the car work how it should. Means there's something wrong somewhere else no?
Yes, weird indeed as I have not heard anyone having to add this.
While fault finding I disconnected all other 'systems' and only had the ignition running and had the same results.
Also tested for parasitic draws from the battery and have none, which should hopefully mean that there is no faults elsewhere.
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Tony Z
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Re: Betty the Oval - Donovan D - ex-MINCE

Post by Tony Z »

acpaterson wrote: Thu Jun 03, 2021 10:40 am But, weird you needed to add this diode to make the car work how it should. Means there's something wrong somewhere else no?
After Dawie mentioned the diode, it rang a bell. I've seen drawings before with a diode preventing run-on, but unfortunately, I couldnt find any to help Donovan when he needed it. The drawing I'm looking for is probably at home somewhere

That said, it isnt a one-off. Not common, but not a one-off
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Re: Betty the Oval - Donovan D - ex-MINCE

Post by acpaterson »

Yo, Donovan,

here's your Bus in another lifetime bud.. ;-)

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Re: Betty the Oval - Donovan D - ex-MINCE

Post by Dawie »

Normally, after switching off a running engine... There is also a small current being fed from turning alternator via warning light to ignition.
Having medium resistance of warning light in series with low resistance of coil, the tiny voltage across coil is way too little to activate a spark.

If we remove the low resistance ignition coil from switched ignition wire, then replace this with a high resistance relay coil...
Alternator voltage to relay will overcome medium resistance of warning light. So there is still adequate voltage left across relay's coil to prevent it from unlatching.
Do'nt assume anything- (While doing fault-finding).
"Things should be as simple as possible, BUT NO SIMPLER THAN THAT."
"If something can go wrong, it will go wrong" (Murphy's law).
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Re: Betty the Oval - Donovan D - ex-MINCE

Post by Edmond »

Here is the drawing you are all looking for
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