MX5 SE Ignition Coils

[phantosmax]

My 04 SE is at the mechanics after the CEL was hard on. The codes were reporting faults in an ignition coil. They replaced with some "compatible" coil but this resulted in more error codes apparently. They think that the turbo SE needs a special coils and want to get a genuine Mazda parts (Bp6d18100a) at cost of $500 each. What advice can ya'll provide?

[and1]

I'm under the impression that the coils are the same from a NB8b with wasted spark setup? What were the faults?

[RS2000]

It seems to be same part no. as any NB8B. Only $163 each for genuine Mazda here:
https://www.amayama.com/en/part/mazda/bp6d18100a

[bruce]

How does a CEL get a hard on?

[phantosmax]

[A.Chen89]

nothing special about the coils; same as any other nb8b/same era 323/premacy

[mx589]

Like everyone else on here saying all nb8b onwards coils the same even same as your se turbo ones

[Nevyn72]

Apparently they're the same as any other NB8b coil.......

[phantosmax]

Thanks RS2000, I've ordered the replacement parts from amayama....awesome site btw

[baddavo]

Hi All,
after having gone through a similar issue with my 2004 SE I thought I would post my experience and findings for those who have NB SE Turbos.
The first symptoms were very intermittent misfire with no CEL or codes recorded in the ECU (OBD2).
Then the misfire occurred more often and the CEL light came on and stayed on. The code recorded was P0351 - Ignition coil A.
I procured a pair of after-market ignition coils (COP design - coil on plug) and HT leads deciding to replace all given the car is 18 years old.
With the coils fitted, I started the car, it idled fine but when I took it for a drive it developed a consistent misfire and the CEL came on again.
This time the ECU recorded codes P0351 (Ignition coil A) and P0352 (ignition coil B).

After protracted troubleshooting (and forum searching) I determined that these after-market Fuelmiser ignition coils are not compatible with the NB SE.
I found that as soon as the turbo comes on boost, that is manifold boost is above zero PSI on the boost gauge, they misfire.

I was able to determine which of the old coils had failed, when hot the primary coil went open circuit.
I procured a new Mazda ignition coil and when fitted with the one good original coil the car runs normally under all conditions.

I took some measurements of the coils which I have listed below. I only used a multimeter so I recorded resistance, not the impedance which would also be useful. All measurements were taken with the coils cold.
New Mazda coil - Primary coil 1.52 k/ohms, Secondary coil 1 to 2: 8.68 k/ohms
Good old coil - Primary coil 1.60 k/ohms, Secondary coil 1 to 2: 8.71 k/ohms
Fuelmiser coil 1- Primary coil 1.35 k/ohms, Secondary coil 1 to 2: 12.12 k/ohms
Fuelmiser coil 2- Primary coil 1.36 k/ohms, Secondary coil 1 to 2: 12.43 k/ohms

I suspect the different values of the Fuelmiser coils don't work properly with the Mazda ECU and cause the misfire with the engine on boost.

P.S. Ignition coil A supplies cylinders 1 and 4 with spark and is mounted above number 4 plug.
Ignition coil B supplies cylinders 2 and 3 with spark and is mounted above number 2 plug.

The auto parts retailer I bought the Fuelmiser coils from did accept them as returns, which I appreciated.

Hopefully this information is useful in the future

[greenMachine]

Thanks davo, good info!

For the moment I am still running the stock SE/NB8B coils, but not the stock ECU, so no error codes or OBD. I have a spare set from a 2003 NB8B I dismantled some years ago, haven't needed them yet though.



PS - great thread resurrection!

[StanTheMan]

I ran the fuelmeister successfully on a VVT NA6 conversion. Mine running more power the SE without turbo. I now have them on a spare Harnes where i can swap it over in 2 min.
Only reason I went back to COP was I cant get the RPM po work with the VVT coils
O also happen to change heads back to BP4W so I can run either set up if required

[Locutus]

How can the ECU detect if a coil has fired or not? Would it be able to detect the difference between a bad/weak coil and a bad ignition lead or plug?

[bootz]

So the first thing, in order of expense is to change the plugs, then the leads and then the coils.