ryandaum

Hi Guys,
I have searched everything i can think of about bad coils.

Got diagnosed as a bad ignition coil, so got a new one. just wondering if anyone has any ways of identifying a bad ignition coil so you only need to swap one out. Things are expensive down under..

Cheers guys

invasion08

iTrader: (7)

http://www.finishlineperformance.com...16-07-1793.pdf

I take you have been getting a flashing CEL? How many miles do you have on your coils and spark plugs?

invasion08

iTrader: (7)

Here is a website you should bookmark, it is full of information.

http://foxed.ca/rx7manual/2003mazdarx8/

ryandaum

Cheers will have a read now.
Solid CEL but diagnosed by local rotary expert with OBD, came up as dead coil

DeViLbOi

iTrader: (1)

Personally I would never replace just one. I know they are costly little buggers but it's just one of those things that gets replaced all at once for me.

invasion08

iTrader: (7)

Depending on how many miles you have on your coils and spark plugs, I would replace all of them. If there are around 30k miles, replace all and inspect your spark plug wires.

WingleBeast

if one went, the others wont be too far behind.

04Green

iTrader: (1)

Flame Vest On...

Those above are right. But, if you want to do just one, the way I would approach it is pull them, one at a time, and look at both the back of the coil and the mounting place. discoloration on the back of the coil, and small pits from arcing on the mounting place. Change the one with the worst damage.

You may also be hearing a small, sharp chirp, when the car starts. If that goes away, you got the right one.

Good Luck.

WingleBeast

there is some debate however if the burn marks is due to arcing or just water burnoff. coils can go weak before they fail, so its hard to pinpoint just one. do what you want though; just trying to save you time in the long run

04Green

iTrader: (1)

Wing,

Question, you talking about the white mark on the coil, or the pits on the plate? And yeah, there is debate. I replaced the coils, had 2 chirps at start, 4 white marks (2 big ones), and 2 pitted spots on the plate that corresponded with the large white marks. Chirps when away after change. But, that is 1 data point. Now, if Ryandaum finds one big white spot, corresponding with one pitted area, and has 1 chirp, and replaces 1 coil to make it all better, we will have doubled the data points to 2. But, he will have saved some money. Right now, saving money is good wherever you are on the planet.

But, yeah, when one goes, the rest will likely follow soon.

WingleBeast

i never really delved that far into the debate, i just got better bhr coils. all i know is when i rotated the coils the white splotch was always on the 1 and 2 coils, making me believe there is water buildup there. but i never inspected too hard for pits when i replaced mine. my cat melted so i just took the opportunity up upgrade while i was at it

Mazurfer

Note to Ryan.............the above is exactly what will happen if you continue on bad coils! This is why you should bite the bullet and do all four. If you think coils are expensive, go price a CAT. Yeah, I know guys.............he could just go catless, but that's not the point I'm making!

ryandaum

So..Decided to check all the coils while waiting for the gym to clear out.
Contacted the last owner who said the front rotor trailing coil had to be replaced 6000mile ago.
Luckily at this time the leads and plugs were done, score.
So i pulled the front two coils and sure enough, trailing had a dirty black stain on the plate.
Pulled the front coil and a VERY dirty black stain was discovered.Far worse.
Swapped my new coil on to the front. Misfire has got a loooot better. Will replace the other 2 after pay day.

Mazurfer

For the record, you can really tell a bad coil from a good one by looks and you can't even really tell a good from bad by the procedure that Mazda gives to verify them with a meter.
Just for the record..............I'm just saying


New ones have also been known to be bad right out of the box, so look out for that one as well.

Good luck!

Jon316G

iTrader: (1)

The ignitor within the coil is what usually goes bad first.
It can't be tested with a meter alone and can't be visually inspected.
Using a timing light is the only good way to verify the ignition... even under load.