Misfire in 1256 engine

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Misfire in 1256 engine

Postby vivapete3 » Tue May 30, 2017 12:56 am

Help! Having tried to fit an Accu spark electronic ignition system to my 1975 HC 1256 Viva,trying to start the car once the system was installed was impossible, so after getting the unit tested by Accuspark and finding no fault, I decided to revert to the traditional points system, now ever since the car starts but has a misfire particularly when the engine is under pressure up hill, a classic symptom of points gap incorrect, since then having replaced, points, rotor-arm, dizzy cap, coil, plug leads, + cleaning and checking gaps on all 4 .plugs, the car still has a misfire, only misfired since I tried electronic ignition my question is , could the the fitting of the accuspark ignition damage the cars electrics? all help / advice gratefully received, cheers,vivapete3
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Re: Misfire in 1256 engine

Postby droopsnoot » Tue May 30, 2017 10:05 am

I can't picture how it could specifically do damage, though I haven't seen the Accuspark system. Is it possible that what's happened is that, while removing and replacing the distributor a few times to fit, remove, re-fit and remove the Accuspark unit, something that was marginal is now worse?

I'm thinking in particular the low tension wire to the negative side of the coil - is it possible the wire was cracked, or coming away from a terminal at one end, and the movement has made it worse? Or any of the other wires, I guess.
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Re: Misfire in 1256 engine

Postby 1972nail » Tue May 30, 2017 11:08 am

I agree with Mike, check all the connections and wires thoroughly. Did you bypass the resistance wire? If you did and didn't swap the coil then the coil is being overrun and will eventually break down.
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Re: Misfire in 1256 engine

Postby rattlyolddt » Tue May 30, 2017 2:12 pm

Without wanting to hijack too much, I am having very similar problems. And thought it best to ask here and keep it together?

I currently have a powerspark elec ignition fitted.

Can anyone tell me how it earths? I have one wire going to the LT negative coil connection, and that's to the module In the dizzy.

So far I've had new plugs, leads, coil, rotor and cap. The ignition system was existing.

Nothing has made the misfire any better.

It hesitates and misses under any load.

Then dies and struggles to restart.

Any help for me or Pete much appreciated
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Re: Misfire in 1256 engine

Postby 1972nail » Tue May 30, 2017 5:00 pm

Are you sure it's an ignition problem? Could be fuel.....

Electronic ignition systems don't like the resistance wire setup or the existing coil of the standard Viva. Have a read at this topic.

viewtopic.php?f=12&t=22328
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Re: Misfire in 1256 engine

Postby vivapete3 » Wed May 31, 2017 1:00 am

droopsnoot wrote:I can't picture how it could specifically do damage, though I haven't seen the Accuspark system. Is it possible that what's happened is that, while removing and replacing the distributor a few times to fit, remove, re-fit and remove the Accuspark unit, something that was marginal is now worse?

I'm thinking in particular the low tension wire to the negative side of the coil - is it possible the wire was cracked, or coming away from a terminal at one end, and the movement has made it worse? Or any of the other wires, I guess.

Thanx for tips, not checked the wiring closely, thanx for your response, cheers,Pete.
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Re: Misfire in 1256 engine

Postby vivapete3 » Wed May 31, 2017 1:06 am

1972nail wrote:I agree with Mike, check all the connections and wires thoroughly. Did you bypass the resistance wire? If you did and didn't swap the coil then the coil is being overrun and will eventually break down.

Hi thanx for advice, no did 'nt bypass resistance wire, but did fit a coil to suit the accuspark system, since reverting back to the points system i refitted the original coil, thanx again for your thoughts, cheers, Pete.
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Re: Misfire in 1256 engine

Postby vivapete3 » Wed May 31, 2017 1:15 am

rattlyolddt wrote:Without wanting to hijack too much, I am having very similar problems. And thought it best to ask here and keep it together?

I currently have a powerspark elec ignition fitted.

Can anyone tell me how it earths? I have one wire going to the LT negative coil connection, and that's to the module In the dizzy.

So far I've had new plugs, leads, coil, rotor and cap. The ignition system was existing.

Nothing has made the misfire any better.

It hesitates and misses under any load.

Then dies and struggles to restart.

Any help for me or Pete much appreciated

Your issues sounds very similar to mine , I've had all misfire symptoms you describe, as I fitted new original coil, new dizzy cap, new points &a new condenser the misfire gradually reduced in intensity, but it's still misfiring, have now run out of ideas, so have approached auto electrician, so I'll let you know the results, thanx for your views, cheers, Pete.
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Re: Misfire in 1256 engine

Postby rattlyolddt » Wed May 31, 2017 2:51 pm

Hi Pete

I as you started down the line of electrical fault finding, as initially the misfire was very violent.

Having fiddled and replaced bits gradually, it has improved, much like you.

I am still unsure if my LT side of things is earthed correctly though.

Good luck!
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Re: Misfire in 1256 engine

Postby ADRIAN » Wed May 31, 2017 9:33 pm

Check the dizzy cap. ALL new caps that you can buy are slightly faulty in that they do not fit snuggly onto the top of the distributor. The locating ring moulded on the underside is too wide, and needs careful filling down, all way round to fit correctly onto the top of the dizzy (preferably with a little bit of play.) If used straight out of box, the cap fits VERY tightly or even sits skewiffy, and the two strong side spring clips can break the plastic, a hairline crack in the plastic thats very difficult to see. Look with magnifying glass. But this crack will produce a misfire when the engine warms up .
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