Just missing that spark

Discussions about MX5 Alarms, Car Stereos, Lighting, Batteries or other Electrical related issues

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Donovan
I only think 5.
I only think 5.
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Location: Auckland

Just missing that spark

Post by Donovan » Tue Dec 01, 2015 10:48 am

My electrical gremlins seem to be on the increase (or I am hoping this one is electrical). Over the past couple of weeks have been randomly down on power and running like a dog like it is down a cylinder or two.

I am starting to suspect that I have either a faulty spark plug or coil. The plugs are those long life jobbies and have only done about 40K, but the coils are the original ones on the motor. I am also hoping that it is a coil rather than plug, as the coils are easier to replace than the plugs, as a couple of the plugs I am pretty sure I will have to pull out my BMC to get them out.

Anyway, I don't want to go replacing all the coils on the whim, is there any way I can check them out or figure out which one is failing if they are?

Angreal
I have stars, you haven't. Deal with it
I have stars, you haven't.  Deal with it
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Location: At the pub

Post by Angreal » Tue Dec 01, 2015 1:48 pm

Doesn't your car have a v8 in it...? I think using the mx5 coilpack is what's causing the gremlins :lol:

On a more serious note, I can't offer any helpful advice unfortunately

evel
I have stars and not afraid to use them
I have stars and not afraid to use them
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Location: Whenuapai, Auckland

Post by evel » Thu Dec 03, 2015 9:58 pm

The easy way to work out if it is a coil is to first diagnose which cylinder is missing (the spark plug will be wet with unburnt fuel) then just swap a coil from another cylinder on to the missing cylinder. If the problem follows the coil, the coil is broken. If the problem stays at the same cylinder, it's either the plug or the coil wiring.

Heres a trouble shooting guide i found on Google for wiring http://easyautodiagnostics.com/misc-ind ... il-tests-1
I haven't read it completely but it looks all good.
'94 S-Special 1800 in BLACK
Flares and 225/45 Semi Slicks.

Donovan
I only think 5.
I only think 5.
Posts: 917
Joined: Tue Aug 10, 2010 10:05 pm
Location: Auckland

Post by Donovan » Tue Dec 08, 2015 10:20 am

problem is, it isn't all the time, only misfires about 20% of the time, and when it does, no where around to stop and pull plugs out.

Have had a chat to the guys that do my tuning, they said chances are it is leads rather than the coils themselves. They have also suggested that because it is happening on a cruise rather than under full noise, that it could be oxygen sensors, so I am going to unplug those and reset the ECU to bypass them, and see if that helps, if it doesn't then a set of leads is on the menu.

Anyone know who sells MSD stuff in AKL, can only find places in CHCH.

SLYDIT
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Keep calm, Forum Moderator here.
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Post by SLYDIT » Thu Dec 10, 2015 8:54 pm

id get the tuners to check your cruise mixtures and timing. if your too lean you can spike Exhaust gas temps and cause a miss, can also overheat the O2 sensor and give issues.

so many tuners just throw in a timing map then shoot for an AFR target but have ZERO idea what its actually doing to exhaust gas temps
RED '90 TURBO.
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Donovan
I only think 5.
I only think 5.
Posts: 917
Joined: Tue Aug 10, 2010 10:05 pm
Location: Auckland

Post by Donovan » Tue Jan 26, 2016 1:41 pm

was one of the coils, in fact the only after market coil that was on the engine for some reason (had all original coils on it when it went to the installers), so no longer running the worlds only v7 MX5 anymore, back to all 8 purring away.

On my 3rd oil filter in about 5000k's, keep ripping them apart on my driveway, really going to have to fix that up someday.

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