Misfire

[arcturus]

A short time before my fire incident I changed to a 123 dizy as i was getting fed up with failing condensers.
On the last trip before my fire i had started to experience a misfire,occasional at first then more and more. eventually I was getting concerned about getting home but the fire intervened. Now I have the car back on the road and the misfire returned with a vengeance. I replaced the 123 with the old dizy and now the misfire has completely vanished. Contacted Amazon cars, who supplied the dizy and am returning 123 for examination.
My question is,are there any other causes of misfire other than ignition?
I might add that a new coil has been fitted and new wiring.

[Army]

In a spark ignition engine the expected source of ignition is the spark. Things however can go wrong see for example =>

https://en.wikipedia.org/wiki/Pre-ignition

To set the record straight - to help add a bit of clarity - you experienced a miss fire as in a missing of a heart beat? In other words the engine was lumpy and felt unbalanced?

[arcturus]

No, as in a hiccup. Not a back fire. As in ignition being momentarily switched off.Not as fuel supply being cut off.

[Ron Kwas]

arcturus;

"...are there any other causes of misfire other than ignition?" Sure...a "Misfire" is a very general term meaning one or more cylinders are not firing and contributing their power stroke to the crankshaft...it occurs due to loss, for ANY reason, of ANY of the vital components required in an Otto Cycle engine: Spark (at the right time), or (a reasonable) Air-Fuel Mixture or even Compression...so troubleshooting means narrowing the fault into one of these groups, then ever more specifically, until we can point to one root cause...

One valid and effective way of troubleshooting a misfire is component substitution, and you've already essentially established that 123 Ign Sys is somehow the cause...but since you've already sent much of the Ign Sys away, there's not much outside of the Ign Coil, (and HT wires, and Sp Plugs ?) left, and so not much left to troubleshoot...let's see what supplier says, bearing in mind that (I fear) they might not have a facility or the expertise for testing this equipment...

Cheers

[arcturus]

I'm now in contact with the makers in Holland with a view to having it returned there. Amazon cars emailed me just before I was leaving for the post office.

[arcturus]

hello again This is the reply that I received

How do you know the alternator and voltage regulator are in good condition?
Is is impossible to measure this with a standard voltage meter.
Very high voltage peaks (spykes) causes misfires.

It could be the ignition gets interrupted by high voltage peaks from the alternator / voltage regulator.

Of course the old fashion distributor doesn't have this problem because there are no electronics inside.

Please do the alternator test first.

Misfires are 90% caused by bad voltage regulation.

first of all the car has a dynamo not an alternator..Would that make any difference?
Secondly how could test out the regulator or dynamo for spikes. Ron?

[Ron Kwas]

arcturus;

If Battery is connected to system, if serves as a very effective spike filter on the power bus, so no high V spikes should be present to interfere with Elec Ign...to additionally filter bus (typically for brush noise when installing a Radio), a capacitor could be connected to B+ output of Dynamo (see: https://www.sw-em.com/Radio_Notes.ht...r_line_filters )
Testing for high V "spikes" will require an oscilloscope...but do I remember correctly is this not a 6V system? Is the 123Ign specified to function on 6V? ...Elec Ign may be momentarily dropping out due to not a high voltage spike, but not being able to work reliably on 6V! Check product specifications! I do specifically recall a 6V vehicle owner on Volvoniacs forum also had ign problems with this unit on 6V...!

Cheers

[arcturus]

What you say makes sense. My understanding is the the only function of the dynamo/regulator is to replenish the battery as the ignition etc runs off the battery. It is quite possible to run the car on battery only until the battery loses its charge.
you don't suppose that he is referring to an electromagnetic signal emitted by the dynamo/regulator being picked up by the electronics in the dizy. Doesn't seem likely to me as the dizy is shielded by the engine block.
Ron, I tried looking in "volvoniacs" but couldn't find anything. pity, it would have been helpful.

[Ron Kwas]

arcturus;

Let me "adjust" your general understanding of your (and any and every other for that matter, irrespective of sys Voltage) automotive Elec Sys ...Charging Sys and Battery are essentially tied together, so when engine is running and Ch Sys is putting out, it provides the power for everything including Ignition and charging the Bat...why, because the Ch Sys output is higher in voltage, and it takes precedence because of the higher voltage...if Ch Sys goes off line, Bat now has the higher V so it takes over for as long as its charge allows...

"...electromagnetic signal emitted by the dynamo/regulator being picked up by the electronics in the dizy." [ The minor brush noise which Gen puts out first rides on the (massive by comparison) power that it puts out, and again it is filtered by the Bat connected in parallel on the power bus.]
"Doesn't seem likely to me as the dizy is shielded by the engine block."[ Don't overthink this!...I think the 6V is simply not enough for reliable function of the 123 Ign!]
"Ron, I tried looking in "volvoniacs" but couldn't find anything. pity, it would have been helpful. " I'll have a look, but I had to do a Brake Job first.

Cheers

[arcturus]

Thanks for the clarification.