mk2 firing on three ?

[jackal]

hi chaps,

my mums mx5 sometimes fires on 3 only

i went to take a look, pulled the HT leads and then it worked find for a 20 minute drive

but since then it has started firing on only 3 again and also the check engine light is on (presumably because of that very reason)

the car was laid up for the winter for 2 months or so with no use

what are the likely suspects ? The HT leads look in fine form. Shall i change the plugs and then start thinking about the coil if things don't improve ?

[Oldandslow]

If you moved the leads about and it worked for a while I'd say it was leads. Also I've had a damaged plug that went a bit intermittent. I'd say inspect the plugs. If they look OK change the leads. Then if still problems change the plugs. Coil would be expensive last resort.

[MX-5 Lazza]

Leads don't tend to last long so replace them and replace the plugs at the same time (probably fine but better to change them when you change the leads).

[Dodd90]

Sure its on 3 not 2?? If its two its most definately the coil pack. Had the same problem with mine. Got hold of a 2nd hand pack and touch wood no problems since

[jackal]

Thanks Guys, interesting.

It was on 2 when I first got it from my mum but on 3 yesterday.

Is there a test for the coil pack ?

[MX-5 Lazza]

The coil pack is 2 coils. One fires 1 + 4 the other 2 + 3. When it fails it runs on 2 cylinders. If it's definitely running on 3 and not 2 cylinders then it's unlikely to be the coil pack that's at fault.

[jackal]

ok thanks very much for that, let me double check exactly whats going on

[snotrag]

You can test the leads somewhat with a multimeter..

Measure each ones resistance, divde by its length, will give you the resistance/mtr.

A 'bad' one will show much higher resistance. They could all be borked though!

I honestly would try changing the plugs and leads - I've had to change my leads 3 times now and I've only had the car 3 years. Also, cheaper ones last as long if not longer than silly coloured 'upgraded' ones, IMO.

There only cheap.

[Dodd90]

I think mx-5 lazza pretty much answered your question either way the coil pack on the mark 2 is pretty easy to change. Only took me 30mins to change

Not sure why but the mark 2 coil pack is much more expensive than the others. Close to £300 last time I looked so get a second hand pack. Make sure you don't throw away the old pack aswell cuz if the new one goes titts up you can swich coils over hope that helps.

[jackal]

damm.. working fine now so cant check

[jackal]

amazing car btw... one of the most fun things ive ever driven

[Dodd90]

jackal said:

amazing car btw... one of the most fun things ive ever driven

Managed to find a wet empty car park yestaday to practice sideways driving..............awesome fun

[jackal]

thanks guys


coil is definitely at fault

any ideas of a good place to get a used one ?

[snotrag]

There's always a number of cars being broken for spares on Nutz, or try autolink as they will likely have one on the shelf.

[jackal]

ok thanks