Firing issue! Please help... D:

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eman8201
Hey. They are NOT Training wheels.
Hey.  They are NOT Training wheels.
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Firing issue! Please help... D:

Post by eman8201 » Wed Sep 23, 2015 8:32 am

Okay... so i'm having a very strange problem with my NA8 turbo mx5. I would really appreciate any suggestion or advice as to how to rectify it.

Basically, my car is and has been running a Toyota coil on plug setup for a few months... in the few months that it was running it dropped 2 coils at different times (i'm pretty sure this was because the coils were mounted really close to the rocker cover and were getting far too hot with the engine bay temp, not heat shielding on turbo etc) but I replaced them and that was that.

I was thinking of ways to lower the engine bay temp to stop the coils dropping out intermittently... but I couldn't help but drive it every now and then :p

Anyway... the last time I drove it just as I was coming in to park it dropped two cylinders at the same time. I replaced the coils and tried to start it again but it wouldnt show ANY signs of life at all.. no firing whatsoever.

After much confusion and experimenting, I found that the car will start on 2 cylinders, ONLY if I conenct 1 cylinder from each of the 2 ignition outputs. The car will then start on 2 cylinders... but as soon as I plug in a 3rd coil it dies instantly.

I am really really confused! Any questions please ask and I will really appreciate any comments.. I'm getting desperate as summer is near!
1995 White Miata

marcellarius
I count 5-s in my sleep
I count 5-s in my sleep
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Post by marcellarius » Wed Sep 23, 2015 8:52 am

Just throwing out couple of ideas:
* Dwell time on your coils. This is the amount of time current flows through the coils to charge them up. Once the coil has fully charged, continuing to hold them on will produce excess heat and eventually burn the coil out.

* Coils not getting enough current. This could be due to a bad ground, undersized wiring or some other source of resistance that is limiting the current flow. It might not be enough to fire both coils in the pair?

eman8201
Hey. They are NOT Training wheels.
Hey.  They are NOT Training wheels.
Posts: 5
Joined: Sat Feb 22, 2014 7:48 pm
Location: Auckland

Post by eman8201 » Wed Sep 23, 2015 9:29 am

Cheers for the reply...

Funny you mentioned dwell as I have had a fair amount of trouble with that in the past. I fried a whole set when I first hooked up the COP setup but have since adjusted it down and the car ran fine.

I have considered your second point... but I can't justify rewiring just yet as it WAS running on 4, and I haven't touched the wiring since... I think youre right though, by the natural of it, it does seem like an earthing problem.

Thanks for your advice!
1995 White Miata

SLYDIT
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Post by SLYDIT » Fri Sep 25, 2015 7:46 am

Most ecus have a setting for cranking dwell and then running dwell. more dwell when cranking. miata turbo.net has the settings. also make sure your earths are 100% as a bad earth will cause the secondary coil voltage to skyrocket
RED '90 TURBO.
SCARING PRIUS DRIVERS SINCE 2002

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