Getting sparks to the spark plugs

Surely if you're trying to make two sparks at once, rather than just one, you'll need twice the oomph?

Pete.

The message from Pete Smith contains these words:

But /each spark/ going down /each lead/ need only be the usual size.

you'll need twice the oomph?

Not so, Wasted spark on exhaust stroke takes less KV to fire and is negative polarity. The spark is not firing under compression conditions.

Hook a scope up an look at each lead in turn (1&4, 2&3) One scope pattern will be inverted due to polarity of spark. The firing KV will be much lower.

Is it actually sparks being seen or the corona ring around the plugs?

I lifted the bonnet last night and the ignition leads weren't too bad, there was only arcing in one small area. However there were sparks around the ends of the spark plugs, and on the ignition coil (it hasn't got a dizzy). On the ignition coil the spark was jumping from near where the ignition lead goes in to a bolt on the coil itself, probably just going to earth! We're gonna try cleaning it, but we may have to replace it. I also went to FIAT today to check the plug gaps (because I think my book's wrong) they're gonna get back to me today. If the plug gap's too big then that could cause these problems, although it never used to give me these problems :-o

Yeah, that's what I meant. When I'm driving the car the misfire's not as frequent, or if I just rest my foot on the gas pedal. The car needs to be warm for any misfiring, although it only takes about 20s of idling for it to be warm enough now :-(

They were brand new so I assumed that they weren't faulty!

You maybe right :-o

I had a look last night and there was a spark jumping from near where the ignition leads plug in, to a bolt on the ignition coil (probably going to earth). We're probably gonna try cleaning it, but I went to FIAT to check the plug gaps to make sure it's not them.

You've had sparks jumping everywhere and you've not started by cleaning everything relevant?

Eh? Big plug gaps causing massive insulation break down and arcing? Nope, sorry, we're not falling for that one.

Peter, if your car is warm after 20 seconds of idling then you need divine help, not ours.

The message from "DocDelete" contains these words:

Perhaps his personal hell hasn't frozen over and is still rather hot.

It doesn't look very dirty!

:-o the sparks will take the easiest route and if the plug gaps are harder to jump than the leads then it will take that route. I changed the gaps to 0.6mm today, but I was shocked to see that they had closed on their own to about 0.7mm. The car feels a lot bigger now, probably because there's a lot more engine braking, and it doesn't feel italian :-(. I think it's still pinking, but I'm not sure. The misfiring may have gone, but I forgot to listen for it :-(. I don't think it's running properly, I'll have to look for sparks across the leads etc tonight.

It did take around 2-3 miles previously, but now it seems to do it after about 20s. I know it's not warm after 20s, but it's gonna be less cold than it was when it was turned on!

btw, I went to a garage and they said none of my tires need replacing. They said there's loads of life left in them and they're nowhere near an MOT failure.

No matey. People with more technical knowledge will shoot you down on this one better than me, but that "big electrode gap" would have to bigger than you've got room for on the plug head to *cause* the insulation to break down elsewhere, it will still spark, but be sporadic and weak. Any charge not discharged will not break down the lead insulation, it will be dissipated back through the circuit (Mr Plowman - help tidy this up please! )

If your plug leads are arcing then that's down to s*it plug leads.

Plug gaps don't close up - unless the piston is hammering them. Perhaps that's your problem?

That would make a very loud noise though wouldn't it :-( Maybe it just looked smaller than it was?

LOL

Dave, you are cruel! ;-)

Only if the leads/ cap/ coil are shagged, for crying out loud. You should be able to run silly gaps without seeing sparks leaking out!

I changed

There is no engine braking, just you breaking the engine.

The message from petermcmillan snipped-for-privacy@yahoo.com (Peter) contains these words:

One tiny click the first time it happened.

After a bit of driving I've reallised it's much worse now :-(. I'll be changing the gaps again when the engine's cooled down a bit.

It was somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember petermcmillan snipped-for-privacy@yahoo.com (Peter) saying something like:

Is this engine braking caused by plug gaps, you think? Perhaps the leads contribute to this too.

Otoh, maybe it's caused by the bloody great lump of fried chicken in the air intake.