NA MX5 Misfiring Issue

fkn · Postby **fkn** » Tue Apr 02, 2013 3:22 pm

Hey guys

I have a '90 Mk1 that iv been happy with, but iv been experiencing misfiring for most of the time iv had it. I changed the leads and sparkies and the problem went away only for a while then crept back up and has started to bother me slightly.

When i hit about 2-3k revs it usually starts stuttering, reving it sometimes gets rid of it but getting out of that range solves the issue. Considering that its the cruise RPM for freeways, it can be annoying. I generally use Shell yellow (normal) and sometimes premium when i want a little bit of fun (dont judge meeehhhh)

Read a bunch of text and so far iv ruled out the following
- sparkies
- leads

Can it be that the fuel i use is too rich or shells just bad? Or coiloverpack? Or CAS (anything related)?

Any help would be much appreciated!

Mike

93_Clubman · Postby **93_Clubman** » Tue Apr 02, 2013 5:09 pm

Might be coilpacks as NA6 ones can be a problem - check inside the coilpack top posts where the spark plug leads insert as this is where pitting will be evident if that's the problem.

dmad_dood · Postby **dmad_dood** » Tue Apr 02, 2013 5:38 pm

Had the same problem in my na8 very recently, i changed plugs and leads and the problem went away for a day, then it came back just as bad. Changed the coilpack and she's been running great!

Sounds like a coil pack.

Jono.

fkn · Postby **fkn** » Tue Apr 02, 2013 6:45 pm

93_Clubman wrote:Might be coilpacks as NA6 ones can be a problem - check inside the coilpack top posts where the spark plug leads insert as this is where pitting will be evident if that's the problem.

I just checked online for coilpacks...

i think my wallet just got a sadface

What should i get (aftermarket or genuine?)

Mr Morlock · Postby **Mr Morlock** » Tue Apr 02, 2013 7:00 pm

Why not save yourself a hassle and get it checked by a mechanic that actually knows what to look for. It will not be a fuel problem.

fkn · Postby **fkn** » Tue Apr 02, 2013 7:29 pm

Mr Morlock wrote:Why not save yourself a hassle and get it checked by a mechanic that actually knows what to look for. It will not be a fuel problem.

I did

His response

"Might be the leads and sparkies, so i changed them. That'll be $150"

and my 2nd time back

"Maybe your sparkies are running too hot or your fuels a bit lean"

I dont mean to flame but if i took it to a mechanic and they fix it, I wouldnt be asking people who knew more about mx5's than a qualified mechanic.

But just for you, i'll take it to another mechanic, i'll let you know how it goes

fcruz3r · Postby **fcruz3r** » Tue Apr 02, 2013 7:44 pm

try gapping the plugs first. That might alleviate the problem, but if it's a faulty coilpack it's just going to come back with a vengence.

fkn · Postby **fkn** » Tue Apr 02, 2013 7:53 pm

fcruz3r wrote:try gapping the plugs first. That might alleviate the problem, but if it's a faulty coilpack it's just going to come back with a vengence.

Sounds like a angry ex-partner...

I'll speak to mechanics about coilpacks, hopefully i dont get burned hard.

I've had a look into NGK Iridium sparkies, would anyone recommend these in a stock mx5 or are these more for project and track cars?

Dweezle · Postby **Dweezle** » Tue Apr 02, 2013 8:06 pm

It if has new plugs and leads that part is fine.
Coil packs are a common issue on older NA6s.

I would try and find someone near you with a spare working one that may let you plug it in and see if it solves the issues?

If it does then you just need to get hold of one.

Mx5PLus or mania may be able to help you out even with a used one.

fkn · Postby **fkn** » Tue Apr 02, 2013 8:09 pm

Dweezle wrote:It if has new plugs and leads that part is fine.
Coil packs are a common issue on older NA6s.

I would try and find someone near you with a spare working one that may let you plug it in and see if it solves the issues?

If it does then you just need to get hold of one.

Mx5PLus or mania may be able to help you out even with a used one.

Would it be not worth buying a brand new one?

Dweezle · Postby **Dweezle** » Tue Apr 02, 2013 8:14 pm

Absolutely if you do not mind the $$.
They will all be over 20 years old for a used one anyways.

But if money is a concern i would at least just try and prove that is the issue before buying a new one.

Dweezle · Postby **Dweezle** » Tue Apr 02, 2013 8:19 pm

Rock Auto in the usa can be pretty cheap for stuff and usually arrives in less than a week.

[url]http://www.rockauto.com/catalog/raframecatalog.php?ck[ID]=0&ck[idlist]=0&ck[viewcurrency]=USD&ck[PHP_SESSION_ID]=34vq70s03nruc6lqb7sslm07v4[/url]

93_Clubman · Postby **93_Clubman** » Wed Apr 03, 2013 10:10 am

fkn wrote:
Dweezle wrote:I would try and find someone near you with a spare working one that may let you plug it in and see if it solves the issues?

Would it be not worth buying a brand new one?

Yeah, if possible borrow one to check if it's the coilpack before buying a new one, or if you can locate, get a 2nd hand one cheaply - some of these should still be available:
viewtopic.php?f=44&t=54091&p=682094&hilit=coils#p682094

search.php?keywords=coil+pack&terms=all&author=&fid%5B%5D=44&sc=1&sf=all&sk=t&sd=d&sr=posts&st=365&ch=300&t=0&submit=Search

erecsean · Postby **erecsean** » Sat Apr 06, 2013 2:31 pm

I had the same problem when i got my mx5. Did the spark plugs and leads and it went away, but then it came back. So i popped the hood while the car was still running amd saw a little arcing coming from my coilpack. I was also unsure whether to buy a new one or a used one. So what i did was, i got a little bit of electrical tape and taped it around the coilpack and lead where the arcing was coming from. Although this will only be temporary, but it helped me to see whether if it was 100% coming from the coilpack. But by doing this, make sure u dont leave the electrical tape on for too long as it will melt. Lol. I got a a used coilpack from a wrecker which cost me $110 compared to a brand new genuine one from mazda which i got quoted for $580. Hope this helps.

fkn · Postby **fkn** » Thu Apr 11, 2013 8:34 pm

Mkay just an update

I bought a 2nd hand coilpack and installed it, initially i thought it would be ok.

Unfortunately i was proven wrong on my way to the casino and it still played up on me - temperature was about 20 degrees

Then on the way back from the casino about 4am - nothing... NOTHING?! i assume it was about 15 degrees

Im not sure if the temperature plays a part but whatever.

A bit more information - Its using NGK V-power spark plugs.

Anyways - just want to get a couple of opinions.
Should i change them to NGK Iridium for the possible heat problem and to help conductivity?
As im using Shell V-power, should i opt for a lower strength fuel? or just Ditch shell and go Caltex or BP?
Can it be the oxygen sensor?
Fuel Filter or Injectors need to be cleaned/replaced?

I wanna do what i can before i take it back to the mechanics - or would that be better?