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Coil packs

When the best plans become completely uncoiled

I’d owned my Nissan Stagea for all of 3 days when a tripled light warning flashed up one night on the way to a friends house. Not ideal considering one of those lights was ‘check engine’ and I figured I’d bought pure citrus.

After a quick Googling it seemed at least one of my coil packs were having a rough time…not an end of the world scenario but not ideal for proper running..

So please tell me, what are Coil Packs?

Coil packs are handy little removable box like objects that sit on top of your spark plugs and build up enough volts to really give those plugs reason to spark. They’re part of your ignition system and when they start to break down, so does your driving enjoyment.

They come in all shapes, sizes and colours.
They come in all shapes, sizes and colours.

So where are my Coil Packs located?

Depends on what you’re driving as to how much work it is to locate your coil packs. On a 1JZ-GTE out of a Toyota Soarer, they’re under a plastic cover on top of the block and take about 10 mins to pull out. On a RB25 Neo out of a Stagea, they’re annoying under a lot of hoses, intake and electrics and take a lot longer. Consult your manual or a friend who has the same model as you do.

If only there were all this easy..
If only there were all this easy..

How do they go wrong?

Occasionally through years of hot temps and spirited driving, they can develop tiny and almost microscopic stress fractures which allows the electricity build up to go the easy route and race out of this new hole instead of straight down into into the spark. Sometimes build quality is not great. Sometimes they just get old and don’t hold as much punch as they did before.

How do I know when one or more after having a rough trot?

There’s a few signs:

-You might be enjoying some spirited driving and an error pops up to ruin your day (On the Stagea Check Engine + Slip + Traction control all light up like a Christmas tree.) After a while it will randomly pop up regardless of level of spirit when driving.

-All of a sudden the sound, feel and responsiveness of your engine changes. One of your cylinders isn’t getting the spark it needs at all and now you’re driving with one less. You might now be driving something that sounds like a WRX but definitely doesn’t move like one.

-You’re just not getting the same fuel consumption as your block struggles with one less cylinder getting the explosion it needs.

-It starts stalling for no reason. A lot.

Can I test them while they’re still in the car?

Yes. One popular test is to remove the plug on the first coil while the engine is running. Did the engine note change? If yes then that coil is working – plug it back in and move to the next one. No the engine sounds the same? You’ve just located a dead coil pack.

Can I fix them myself or do I need a new set?

Well once you’ve launched a full investigation and worked out it’s 100% all the coil packs fault, you can try the following:

Flexane/Urethane coating to seal any cracks


CRC Urethane spray

Hi temp tape (doesn’t seem to work that well)

Note: While this will help seal the cracks, it won’t make tired old Coil Packs any less tired.

There is the possibility of swapping out the failing ones but a lot of people prefer a whole new set.

Alfa Coil Pack having a bad day
Alfa Coil Pack having a bad day

I can’t see no cracks! How do I find out if my coil packs are still up to spec?

Well firstly Google what resistance the coil pack should be holding and break out the multimeter! (here’s an example of what you’re looking for on a Nissan RB26) Mine seemed to be a few ohms higher than what was usual meaning they were getting tired. So I bit the bullet and bought a new set – at $400 for a set of Yellowjacket’s it wasn’t the cheapest option but it saved stuffing around and I’m still yet to see a usual error pop up in day to day driving.


While you’re down there…

If you’ve gone down the route of grabbing a new set of factory or after market coil packs, you might as well throw in a set of new spark plugs while you’re at it to have everything running smoothly.

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