It never ends. Factory ECU died. Replaced but immobilser ...

93_Clubman · Postby **93_Clubman** » Tue Nov 01, 2011 1:32 pm

As you know coilpacks are a common problem on the NB8A. Early NA6 coilpacks were also a problem from time to time. Had to replace my NA6 coilpack due to deterioration of the contact surface inside one or more of the coilpack posts (pictured above).

However, I'm not sure how the NB8A coilpack problem visually manifests itself in terms of identifying a faulty coilpack, if at all. If you've not already tried it, the best suggestion I have is to borrow an NB8A coilpack, swap them over, & test drive.

devski · Postby **devski** » Tue Nov 01, 2011 2:00 pm

If i knew anyone around here with an mx5 I would, however it also looks like a massive pain in the arse to remove the coilpack.
I cleaned the contacts and they are now at least visible.

It has started rev hunting now if you hold the throttle at a steady level. That combined with the stalling makes me think the MAF is indeed stuffed.

I love how my mechanic checked the wires and coils and said they were fine, If you had seen that surely you would have at least cleaned them contacts up?

Theres also a split on one of the insulation boots on the wires

Im actually considering replacing the wires and MAF and if that has no effect replacing the coil pack.

93_Clubman · Postby **93_Clubman** » Tue Nov 01, 2011 2:25 pm

Coilpack removal on NA8 isn't that bad, but I've not tried it on an NB8A.

Fairly uncommon for the MX5 MAF to be a problem, except as Andrew mentioned for the loom to MAF connection.

Was tempted to mention that given the amount of time you mentioned before that your mechanic had the vehicle I'd have thought the basics would have been checked. Indeed, even if they didn't have it that long, they should have checked the basics.

Certainly worth replacing the plug leads if you haven't recently, & again useful if you could borrow a MAF as they're not cheap new, but difficult if there's no one you know with an NB8A nearby.

Steampunk · Postby **Steampunk** » Tue Nov 01, 2011 6:50 pm

Those are some funky-looking lead connectors. I've never seen anything like them. What brand are they?

So the coil pack wells were really sooty-black? That's not right. This is what mine looked like after more than 125,000km.

You mentioned leads and plugs were checked, this was all done by the mechanic yeah? and you didn't double check? If not, then grab a set of leads that definitely work, ie. from a running car, and put them on. It doesn't have to be leads for an MX-5 specifically, as long as they fit and attach to the packs & plugs securely.

If you have spark plug sockets, then I would also check them, not just for condition, but to check they are in there nice and tight.

Also, all vacuum/intake lines are secured yeah? Go over everything visually. Write down each one as you check it so you know everything has been inspected.

devski · Postby **devski** » Wed Nov 02, 2011 8:03 am

Yes, The plugs and leads were "checked" by my mechanic. Didnt think to double check because I thought that was pretty basic.

Check the plugs yesterday, all in good condition and tight. Very black but no gunk or oil.

Regardless, because they aren't very expensive i'll replace them when my new leads come from mania. I'll also check the coil pack when I have the new leads.

I really appreciate the replies. Without the knowledge I've gotten from here i'd be up the proverbial creek.

devski · Postby **devski** » Wed Nov 02, 2011 2:42 pm

As for the brand it doesnt actually say on the wire. Just says "Genuine silicone" lol. Couldnt get any NGK wires so I ordered some top gun wires. A good investment I feel.

Steampunk · Postby **Steampunk** » Thu Nov 03, 2011 2:09 am

I'm wondering where the black sooty stuff came from. Arcing leaves white-is/grey-ish residue... Maybe the plastic from the cheapie leads?
I don't know if you have a preference re plugs, but I have a set of new Bosch Platinum Ir Fusions doing a good job of collecting dust.

devski · Postby **devski** » Thu Nov 03, 2011 2:43 pm

New leads made no change. Car is now idling at 500rpm and spluttering. Any throttle at all causes it to stall.

If the I test the coils tonight and everything is fine with those then the only thing left I can think of is ECU seeing as the ECU controls idle and all of the ignition is fine.

Or perhaps a manifold issue.

Either way if Rev9 ever get around to shipping the Jenvey kit with Megasquirt that i've paid a deposit on then I should be covered...

93_Clubman · Postby **93_Clubman** » Fri Nov 04, 2011 6:17 pm

Given they didn't check the leads properly, & possibly other things, reckon it's the coilpack.

adrianciaff · Postby **adrianciaff** » Fri Nov 04, 2011 10:07 pm

i had a very similar problem on my old NA6, pulled my hair out trying to figure out what was wrong... turned out it was the coil pack, got new leads too. 80 bucks from a wreckers for a used coil pack.

for the record if your mechanic missed basic things like that i wouldnt be going back to that mechanic again, if he knew that they werent the problem he would have at least advised you to buy new leads.