K10 ignition coil, and associated problems?

[penny11]

Helo all,

I hope someone can shed light on this please?
I have a K10, 1991 with electronic ignition, but it also has a condenser! What does this condenser do, and what are the symptoms if it fails? Does anyone know?

The care is fine when it is dry, but is reluctant to start when it is damp. New dizzy cap and rotor arm, plugs and leads.... the only thing left seems to be the coil or this condenser. Nissan say it doesn't have one (condenser), the Haynes (ha ha) doesn't show a correct wiring diagram so i don't know where to go next......

Many thanks in advance .....

 

[SammoHung]

A 'condenser' is a 'capacitor' in fundamentalist electronic terms...on the K10 it looks like Half of a AA battery, silver in colour, its bolted to the chassis somewhere near the coil and has one wire coming from one end.

Its purpose is to slow own the very fast-switched high voltage spikes that are necessary to produce a spark. Fast high voltage spikes radiate very easily as radio interference that causes peoples TV's and radios to speckle or crackle at the same frequency as your current engine speed

Some people hear their engines through their radios or cassette / CD players in the car...quite often this is due to a worn or disconnected condenser.

If your condenser has absorbed moisture then it may be placing a parasitic load on your coil which could hinder starting but this is VERY UNLIKELEY in my opinion. If you want to check if the condenser is a problem, you could temporarily remove it before attempting to start the engine and see if suddenly you have life!...but if its still sluggish then your condenser is not causing your problem.

my car is fine in general but when i park it overnight on damp grass or in fog it needs some persuading to start...lol


hope this is of some use

 

[Mraider]

I have similar problem when it is damp.
Some mornings it started really poorly or engin stops on the road sudenli and wont start untill some time later untill today it finally died. The spark is lost some where it some time is and then it isn´t there. I have tried all the tricks to meikit work but no luck. Tomorrow i´m going to faind a new ignition coil.

So i´d like to have som advice to.

 

[Arnold]

I have similar problem when it is damp.
Some mornings it started really poorly or engin stops on the road sudenli and wont start untill some time later untill today it finally died. The spark is lost some where it some time is and then it isn´t there. I have tried all the tricks to meikit work but no luck. Tomorrow i´m going to faind a new ignition coil.

So i´d like to have som advice to.

Mine did that recently and it was the distributer which was faulty.

 

[Mraider]

Ok I just read about your damp problems.
But what wos the problem whit the distributer did the shaft moved side to side or something

 

[Arnold]

I cant remember the exact fault but there's something electrical inside it which just gives up when it gets old or has covered lots of miles, roughly 100000 approx. Over time, the fault just gets worse and worse until it gives up.

Mine was misfiring, cutting out and basically just being rubbish & unpredictable until it was replaced.

 

[Mraider]

Wich distributer are you speaking mechanical or electronic.
I hav mechanical but it seams fine.
Main problem is that spark is gon.

 

[Arnold]

Wich distributer are you speaking mechanical or electronic.

The distributer which doesnt use points, the electronic ignition one

 

[Mraider]

I took the distributer of and cleaned it a bit and lookt ower som connections and my micra is alive again.

 

[willzy_69]

If the car cuts out immediately randomly with no spluttering and wont start again for some time it is likely to be the coil. The coil is a sealed unit filled with oil and well . . . . coils. When these get old they are less effective and with all resistant materials they perish, but this perishing is internal. When the coil gets hot it will expand, sometimes enough to break a connection internally until it is cool enough to 'shrink' and complete the connection again. I have had this problem and finding the problem can be a nightmare, good liuck tho.

oh an coils arent that expensive £20 ish inc delivery from az motors or similar outlet

 

[Arnold]

I took the distributer of and cleaned it a bit and lookt ower som connections and my micra is alive again.

My replacement is starting to go wrong again lol! Mis-firing and loss of power, should hopefully change it saturday.

 

[bobsp16]

It shouldn't have a condenser onit at 91,If its got the distributer with the points in throw it all away even coil and fit the electronic dissy and coil off the ma12 one they alot better, but not off the late ecc one.

 

[penny11]

:doh:

yes, that is what Nissan say, but it DOES have a condenser ..... whether it is any use, I don't know... ?

However, i think i have worked out, it is the coil? The other day i listened to the coil closely, and you can hear it 'sparking'....i know it isn't actually sparking, but you can hear it click with each spark at the plug, so i guess it is tracking internally, or failing somewhere, so i have got a new coil, waiting to go on when it is warmer....?

i will let you know how it goes .....

thanks for all the advice .... :grinning:

 

[SammoHung]

Penny,

From what you have described..my money is on that; you have found the problem and that your new coil will fix it....even if it doesnt though..all it not lost as ignition components can get tired (develop losses that can cause in efficiency but not necessarily failure)

Mine is 1992 and I do have electronic ignition AND a condenser (surpressor)....the condenser helps to stop your car from interfering with peoples TV's etc when you drive through their streets...that's all.

Good luck with your new coil...let us know ow it goes

 

[Andrew]

The condensor in an ignition system does a lot more than stop the RFI in a points based ignition system, and also in some types of electronic systems. It stops arcing on the points (and hence the RFI), but the primary reason it is done is to stop the energy being wasted. It also forms a resonant LC circuit with the coil, and this makes the spark a lot more power. Try to get a coil to spark any reasonable distance without it, and it won't work.

 

[SammoHung]

It stops arcing on the points (and hence the RFI),

agree,

but the primary reason it is done is to stop the energy being wasted. It also forms a resonant LC circuit with the coil, and this makes the spark a lot more power. Try to get a coil to spark any reasonable distance without it, and it won't work.

I can't get my head around that:
If this were a sinusoidal AC circuit I would agree but...
this is a switched-mode DC circuit though, (points or electronic ignition breaks the low voltage primary side circuit <enter Lenz's Law as the dominating principle>)

so the energy for a long gap jump is provided by the building then collapsing magnetic field in the coil (transformer) core...

surely any series or parallel capacitance would suppress the peak voltage
developed across the primary...and hence the HT secondary?

I need a drink!!!!

 

[Andrew]

If this were a sinusoidal AC circuit I would agree but...
this is a switched-mode DC circuit though, (points or electronic ignition breaks the low voltage primary side circuit <enter Lenz's Law as the dominating principle>)

surely any series or parallel capacitance would suppress the peak voltage
developed across the primary...and hence the HT secondary?

Why does it have to be a sinusoidal AC circuit to be resonant? The circuit isn't steady state, so the voltages and currents are changing, hence resonance can happen.

The condensor is to suppress the voltage across the primary so that there is no arcing on the points. However, the instant that the spark jumps the gap on the spark plug, the resonance happens.

 

[SammoHung]

Hi again,

Maybe we're just getting our 'wires crossed' HAHA get it (WIRES-crossed)
Never mind that was a super crap joke....

Why does it have to be a sinusoidal AC circuit to be resonant? The circuit isn't steady state, so the voltages and currents are changing, hence resonance can happen.

Yeah, youre right, I didnt' mean to sugest that the circuit wouldnt have resonant frequencies. I just meant that it would have to be close to pure sinusoid for on single capacitor to be able to tune it.

The condensor is to suppress the voltage across the primary so that there is no arcing on the points.

yep agree

However, the instant that the spark jumps the gap on the spark plug, the resonance happens.

yep agree too but:...I reccon the waveshape for the voltage and current fir a discharging (sp)arc would be pretty far from sinusoid and much closer to an impulse response. So I was thinking that there would be a whole series of descrete frequencies <Fourier aproximation>

.....I've just had a barmy thought(another one)..may be this is what you were saying all along (but with different words) what do you think?

The surpressor reduces the peak primary voltage by allowing more curent to flow in the primary winding.....this increases the input 'power' (VxI) to the coil.

If there are no losses in the coil..the same (increased) power is transfered to the secondary....this means for the (now slightly surpressed) voltage produced there is now more charge available to flow as current in the discharging spark...so the spark becommes fatter/brighter giving a better igition of the fuel?

Thoughts? I never looked at it like this....maybe I shout reat myself to a new coil and condenser just for good measure?

I still reccon it couldnt jump a further spark gap though as this definately down to peak voltage and what is between the air gap.

 

[Andrew]

This is how it works:
The points are closed. The voltage across them is zero, as is the voltage across the capacitor.

The points open a minute amount. The voltage across the capacitor is still zero, so it will begin to charge, thereby gradually increasing the voltage across the points.

The points continue to open, until they are open enough that the spike from the primary can no longer bridge the gap. The capacitor should stop charging just after this.

The current has now stopped. As you know this means that you should get a big spike on the primary, causing a spike on the secondary.

Now you have a voltage spike in two connected coils (which both have a huge amount of parasitic capacitance), with an inductance and a capacitance in series, hence you get resonance.

You don't need a sine wave for resonant effects to occur. You don't even need to think of it in terms of Fourier and the component sine waves.

Whatever the case, it's actually a stupidly complex problem to analyse in great detail. The coil itself is nothing like a normal transformer (there is no magnetic circuit inside it, causing huge leakage inductance, something to do with trying to maintain current rather than voltage on the output), and strange things happen. I tried writing a Spice model for it at uni, and gave up, mainly due to the fact I had no idea how to model the spark gap.

 

[SammoHung]

The coil itself is nothing like a normal transformer (there is no magnetic circuit inside it, causing huge leakage inductance, something to do with trying to maintain current rather than voltage on the output), and strange things happen.

Didnt know that....you mean more like an autotransformer (primary not isolated from secondary?)..there must be some kind of core?

I tried writing a Spice model for it at uni, and gave up, mainly due to the fact I had no idea how to model the spark gap.

Yeah...lol, this guy failed with that...keep at it though you might blow him out the water....lol
http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=178055

 

[Andrew]

Didnt know that....you mean more like an autotransformer (primary not isolated from secondary?)..there must be some kind of core?




Yeah...lol, this guy failed with that...keep at it though you might blow him out the water....lol
http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=178055

Well, the primary and secondary are connected, but not in an autotransformer way. There is a core made out of steel, but it isn't in a loop.

That was one of the papers I looked at. But you have so many different parts of the system:
Car battery/alternator - doesn't behave like a simple voltage source
Ignition coil - not like a normal transformer
Ignition leads - not just a piece of wire
Spark plug - well, it's a spark gap and behaves weirdly

I just couldn't get anything stable out of it... was just interested to see if you could work out what actually happens. I don't think anyone has every bothered, the system just works.

 

[SammoHung]

I bet motor designers & manufacturers have their own spice moddles but they won't share them with us?...lol

Wait a minute is penny still with us???

lol

Penny? did you get sorted??

(we got carried away, sorry)