How Do You Check The Health Of Your Coil Packs ?

[Munkyb0y]

I've seen it mentioned that you can check your coilpacks with a multimeter to see if they fall into certain tolerances. ie healthy or not.

Can anyone expand on this? How exactly is it done?

I want to identify which pack/s are suspect.

[Munkyb0y]

after a bit more searching, nothing really came up, but from what i can gather, you need to test the resistance across the + - terminals on the top of the coil pack. anyone know what the values should be? or in fact if this is the way to go about it?

Edited October 16, 2007 by Munkyb0y

[QWK32]

after a bit more searching, nothing really came up, but from what i can gather, you need to test the resistance across the + - terminals on the top of the coil pack. anyone know what the values should be? or in fact if this is the way to go about it?

0.6 to 0.9 ohms according to the service manual.

[Richieb]

From what I know, they should read about 0.7 ohms(primary). Secondary is the doubtful one though. I dont have a real way to test this, but I know you should get a big phat blue spark from it if you connect a plug on it to ground.

If not blue and seemingly powerful, then it is dodgy.

There is, according to what I know only one way to test its output, and that is complex, as the requirement is pressure in the same confined area, plus a guage sensitive enough to measure in KV.

If in doubt, go buy a single one from a breakers like I did.( I found a late model GTR in a breakers in Greenacre, and they will split individually)

If you carefully remove the silicone rubber plug part, you will see that there are one of two things in there, dependant upon vintage.

I have noted that if you look at the top of the spark plug, and find it has been blackened by spark arcing, then you probably will have a duff coil, as the spark will try to find a quicker route to ground, and very quickly will create it's own Freeway to Ground, which you cannot remove reliably(learned this from working on 33Kv 330Amp systems)

This "Quicker route" has been noted by myself in this instance to be INSIDE the bakellite/plastic former.

I sanded (what i had ascertained was the duff item) the surface off the plastic, and discovered it had 'Tracked' through, thus being hidden away from the usual way of spotting it!!

I opened all the spark plug channels, and discovered that the spring, or spring and carbon rod had shortened itself in a few instances.

I gently took each one out, and carefully stretched the spring/carbon contacts to all the same length of protrusion from the contact in the HT side, cleaned them all with isopropyl alcohol, dried them, and then reassembled them... plus I did the same with the replacement item!!

I had a problem with my ignition, which turned out to be one coil, and I believe(IMO) that the orig Nissan items are just as good/if not better than the after-market devices on sale, short-fall of an external Hi-energy race coil setup.

Anyway, the car was duly tested, and BINGO, all is good for the princly sum of $50.

I am not a tight-wad, but if I can work-out that only one coil was stuffed, then why pay upwards of $500 when the reast are in perfect working order... even after almost 18 years!. I have spent $13k nearly on my motor, and I decided there is a diff between being overley silly with my cash, and not.

She now is back to 417Kw at the 4 wheels, running on good old trusty Nissan coils, and I have not noted any problems since.

[Munkyb0y]

i take it that measuring the primary resistance isn't definitive. but i'll check it anyway. a big variation in a single coil would be suspect.

i've pulled the coils out and cleaned the spring and the seat/contact area. (shown below)

i think that's what you explained above.

this reduced the missfire, but didnt fix it entirely.

I know you should get a big phat blue spark from it if you connect a plug on it to ground.

If not blue and seemingly powerful, then it is dodgy.

can you explain this process to me in more detail? how do i go about it exactly?

Edited October 16, 2007 by Munkyb0y

[Richieb]

For sure, any big deviation is a problem, I think I would bin them if they exceeded 8.5 Ohm on the primary side, or less than 0.055.( personal limits I have set, and noted through my time with spark problems btw)

You might find that the spark has actually arced through, as opposed to over the surface of the coil plastic, which is what foxed me at first, as I could see no outwardly visible sign of the tell-tale hairline mark, because it had gone actually through the insulator.

I have the offending item on my desk here, as a symbol of triumph!!

I reakon that(IMO) if the plug contact has a "Arced/eroded/blackened appearance, it will have been strained to jump 2 gaps in the time of spark to that plug, as one is under pressure, and one is not (two totally diff mediums) then there is a good bet that the spark will have attempted to break-down another way to ground, (sometimes via secondary windings to a easier exit!!)and probably will have signed the death warrant of the coil in question.

You could do the ME trick, and for $50, I solved it all by substitution.(certainly beat the $1k I was quoted)

BTW, I am not suggesting in anyway that new ones are not a viable remedy, it's just I have salvaged my ignition system for a miniscule cost. I WAS going to go for the JJR, or a MSD system with external Hi-Energy coils, but I had a few hrs spare, and threw caution to the wind, so hopped in the run-about, and tracked some down. he let me chose which one I wanted, with a guarantee(which is nice!!)

I will, and do still buy from SA's sponsors, and recommend them fully, there's some good prices from them, and some quality equipment to boot.

[Richieb]

BTW, be careful with use of the silicone, as it will track if it isn't allowed to dry/cure completely. once it tracks, it tracks forever.

You have to be sure of its chemical properties, and whether it has a stated di-electric strength.

I still believe there is no substitute for cleanliness when it comes to HT voltages. Make sure the crap that has built up over the years inside the plug cap/former from grubby oily fingers when holding the plugs before installing them has been removed/cleaned also. This has a habit of baking and carbonising, leading to tracking/arc path.

[Munkyb0y]

thanks for your replies richie. very in depth

that silicone is selleys 401 industrial high temp, recommended for electrical insulation among other things.

can you tell me how to check for the strong blue spark?

do i just take the coil with spark plug attached, while the car is idling, and earth the spark plug on cam cover to create the spark?

or do i do it with no spark plug, and just earth the coil contact area directly? is this safe to do?

although i dont know if this would help, as i dont have a miss at idle, only at full boost - 12psi.

what spark plug gap are you using?

Edited October 16, 2007 by Munkyb0y

[Richieb]

No worries Tony, a skyliner in need, is a mate.

Defo use a plug in there, as it will allow the HT to find another route to dis-charge!!

Be sure to allow the Silicone to cure fully before lighting them up again though.

There should be a strong blue spark at the plug tip, with a clear clicking noise, as it tracks to ground through the plug outside casting when you turn the engine over.

If it can be avoided, never attempt to fire the car without a good track for the spark to ground, it will wreck the coil insulation for sure by finding an easier path.

Last info was .7 as a gap goes.

Mine would not run well even on 14psi, it mis-fired and all noises.

I noted it was a little "iffi" if I listened hard enough on idle, but this was very hard to distinguish.

Usual driving pressure made it show its problem about 4500-5000 rpm in second and third. It manifested itself as a quite distinct "Hic" at first, and then had fits of splattering all over the place. I actually got to a stage of shutting the boost down to waste-gate pressure at one point, as it was getting progressively worse through the night.

From 24 psi to nothing in one evening..!!

[Richieb]

BTW(again)

Make sure the spring/carbon contact is well in contact with the plug electrode. You'll hear it make a "Springy-creak" as it presses hard on the top of it.

Did you note any plug top electrode burned at all, 'cos I rekon you'll find that that coil is NFG, or at leas weakened, which will show once you crank-up the pressure at around 5000 RPM. see a dip in the dyno chart, or an odd change in exhuast note about then, and it is pretty certain one is down.

[Munkyb0y]

i just had the car out, 6500rpm, 12psi, 2nd gear, no misfire at all. but i'm sure its not gone for good.

i am 100% that cleaning and sealing the coils (2 weeks ago) has greatly reduced the problem. (thanks to the tutorials on this forum)

before i did that, i was getting a huge, power draining missfire as low as 4000rpm on 12psi.

i will have a go at stretching the springs as you mentioned.

i'm still running 0.8mm gap, and prefer to keep it that way if possible.

also, i just swapped my ngk platinums to ngk coppers.

Edited October 16, 2007 by Munkyb0y

[Richieb]

Plug change is a good idea, as, imo, there is nothing to gain apart from hi-Km's from them... but who would trust that part.

Got to admit, I had a little doubt at first when mine was fixed..!!

The cotact springs should be securely/firmly in contact with the top of the plug at all times, as a small gap will very quickly erode the contact, and cause the HT to look for an easier route to ground..... usually via a dust covered route, or imperfection elsewhere.

Anyway, like I said, and it is good advice to all here... "There is no substitute for cleanliness around HT".

Happy drivin' mate, enjoy.

[Stormchaser]

I am having a simillar problem with my r33 gtst.

One day just cruising home after a bit of a hammering I noticed what felt like ignition breakdown.

it shuddered, backfired but I was only about 2 mins from home.

I left it over night and the next day it was fine again.

It idled smooth had power all the way to redline, no hesitation so I thought maybe it was bad fuel.

So then a week later I drove it about 45kms and it started doing it again but much worse it also developed a missfire at idle. Sounds like a wrx and is barely driveable.

Does this sould at all like the coil packs?

[Richieb]

On the balance of probability...

Yeap, sounds like you have a duff one in there... it did the same to me, then it progressively gets worse...!!!

Buy a good one from a breakers, and substitute it in, eventually you will find it, but look at the top electrode of the plug to see if it blackened or burned away.

If you spot one, i'll lay odds its that coil thats giving you the trouble.

[Stormchaser]

On the balance of probability...

Yeap, sounds like you have a duff one in there... it did the same to me, then it progressively gets worse...!!!

Buy a good one from a breakers, and substitute it in, eventually you will find it, but look at the top electrode of the plug to see if it blackened or burned away.

If you spot one, i'll lay odds its that coil thats giving you the trouble.

ok so I have pulled all of the coils out of the car and all of the plugs.

The plugs seem fine no burned or shorted arcing marks on them.

Then I had a look at the coils

This is what I came up with

I noticed that on three of the coils there were these wierd "hot spot' kind of marks.

Im going to get a set of copper ngk's and gap them to .8 to see if that makes any difference.

If not then it looks like getting a set of second hand coils to diagnose them further.

[PLYNX]

I had a similar problem with my coils ! Yep they were cracked. I just cleaned then with solvent then coated them with polyester resin twice and that fixed it no problem. If you use the silicon some times it fails under excessive heat or even poor application. The good thing about the polester resin is that it gets in to the very fine cracks you cant see. If you use silicon on the coils first forget about the polyester resin as it wont stick to it .

[Stormchaser]

ok so I have had another look and I cannot see anything wrong with the plugs.

Do the scorch/burn marks on the sides of the coils look like that is what could be causing the problem.

I cant really just go and get one form a wreckers cause it looks like 3 of them are doing the same thing.

Would the car be even drivable if three coils were intermittiantly failing?

It drives just not very well at all.

I was just going to clean them up and tightly wrap electrical tape over them, just to see if I could eliminate the problem even for a bit, so that I wont mind spending 500 on a set of splitfires.

Thanks for your help.

Jason.

[Richieb]

Ya can go to wrecker for 3 of them for sure.

I would think that these marks are not good for HT circuits. They could be carbon'd up, or worse still, allowing tracking to ground along/over them.

Mate, change them out, they look tired..!, and from the pic, I am sure I can see a mark where it is arcing.

Your call as to what with tho. I stuck with Orig items, some swear by Splitfires, and now theres the JJR ones.

Depends on budget, and how you would like to progress, but all offer warranty... even from a wreckers.

[PLYNX]

Where are you located ? I'll coat the ones that you think are giving you probs for free with polyester resin ! What have you lost ? If it works good ! If it dont them buy the ones you need ! Thats a hell of a saving if it works.

[Stormchaser]

I live in The Southern Highlands area of NSW.

Where are you located?

Im considering getting a whole set of secondhand ones if the resin doesn't work, what should they cost me from a wreckers.

I can get a set form ebay for about $180 shipped. Does that sound reasonable?