Car running weirdly

[Okibi]

http://forum.miata.net/vb/showthread.php?t=310143&highlight=toyota+coil

[JBT]

So now I'm WTF, at least before the misfiring had some sort of pattern, I could never get it to stop misfiring in the afternoon or when it was hot, but it seems to work fine now

Is it possible that the leads have never been properly connected/seated at the coil or plug ends?

[philz]

I'm actually highly expecting this at the coil ends, because I just started it up again, and its seems to be fine.

Spark Plug ends were checked at least 5 times.

Though Coil ends, were only seated once, and never taken off and put on again, though I did swivel them around in position.

I'll give it a few more days, and see how we go

[philz]

Alright,

Today up until now, I've started the car 5/5 times it has worked, so I'm guessing it was just the leads weren't properly connected.

1st start- drove it around normally, engine and everything is fine.

After that did 4 engine starts at idle, again fine

So after number 5, decided to give it a flogging, to make sure, since it's nice warm weather to test out the coils, doesn't hurt to try.

Engine is already warm.. decide to punch it, WOT first gear up to 7k, shift, then loss of power.

Crawl about 100ms ( but crawl better than those other days), until I stop at a rounabout, once I enter the roundabout, power is back.

Stop to turn back into my street, go slightly hard, around 4k, then misfires again, idle goes way down, very violent shaking, clutch in to make sure it doesn't stall, as I enter my driveway, clutched in with 1st gear, power is back, no missing.

Pop up the bonnet, do the coilpack check, all sparks fine, but this is when the car has stopped missing.

So now start up seems to be fine, driving is now 50/50, not quite sure yet.

edit: After this, did another engine start, again it's fine.

Edit AGAIN: Started it up, one last time for day, no missing, decided to drive it around the block, probably not hard as before but still giving it, 4-5k, no power loss, engines fine. *fingers crossed*

[Okibi]

Although it sounds like my problem with the coilpack (and/or) O2 .... have you taken a look at the crank angle sensor, the one that reads from that plate at the crank pully, if that's loose it might move under hard acceleration and make the car run funny, then fall back into place.

Probably worth looking at your harmonic balancer while your there and make sure she's not loosey goosey.

I also had my car stumble a bit under heavy acceleration, part of the plastic inside the top of my K&N filter had de laminated and under spirited acceleration it would get sucked up against the AFM reducing power noticably, it wasn't until I looked inside the AFM did I spot it.

ALSO .. I think the PCV valve struggles once you make an MX-5 breath more, perhaps it's sucking in air/oil from your crank case and making it run rough.

My money is still on coil packs, looks like almost 50% of NB8A owners on the Miata.net have had coil pack failure.

[philz]

Yeah my money was on coilpacks as well.

But since yesterday when I played with the leads to the coilpack, everything has been fine since...

Before I could only start up the car, and let it idle without misfiring in the morning, now the car will start fine any time of day. And driving it around seems to be fine for now, I haven't had that massive loss of power compared to before.

I've had suggestions it could be fuel problems when I drove it hard?

edit: So I decide to start it again.
And it finally misfires on idle, I open the bonnet, take out the number 4 lead at the coilpack, and because the ground is close... the spark jumps to it, and I put the leads back in again, and it works. ( note: I only pulled out the 4th lead, and put it back on, and it worked... did not touch 1,2 and 3)

So I'm thinking it could be something to do with securely fastening it on? Zips ties anyone?

[RG.net]

Yeah my money was on coilpacks as well.

But since yesterday when I played with the leads to the coilpack, everything has been fine since...

Before I could only start up the car, and let it idle without misfiring in the morning, now the car will start fine any time of day. And driving it around seems to be fine for now, I haven't had that massive loss of power compared to before.

I've had suggestions it could be fuel problems when I drove it hard?

edit: So I decide to start it again.
And it finally misfires on idle, I open the bonnet, take out the number 4 lead at the coilpack, and because the ground is close... the spark jumps to it, and I put the leads back in again, and it works. ( note: I only pulled out the 4th lead, and put it back on, and it worked... did not touch 1,2 and 3)

So I'm thinking it could be something to do with securely fastening it on? Zips ties anyone?

cable ties fix everything! my cam angle sensor is cable tied

i have had a similar problem to what you had today, underload the car would backfire and loose power, my rev gauge went all spastic too, which was quite wierd and rather scary as i was coming home from work in peak hour.

Anyway when this happened to me, the car actually stopped twice on the way home, in the end of it all it was my cam angle sensor.

however i did change my fuel pump a few days after this incedent and it hasnt happened since, actually come to think of it when the car was at idle, it was a little rough, but i didnt take much notice.

[philz]

Well car is running fine now, starts up, no misfiring, drove it around how I normally would, not cut outs loss of power or misfire during driving.

But what I have noticed is, that the exhaust is definately louder than before, not super annoying loud, I do have an npower exhaust, so it's quite subtle sports exhaust, but it's much more deeper sounding, and the only time this exhaust gets more deeper is when your drive the car hard for about 30mins.
I've only dríven it for about 5-10mins, and it's already at that sound, unless the misfiring before caused something?

I have also noticed that the idle goes down much quicker?
For example, if you drive the car for about 1-2hrs, engine is hot etc, and so you can't really move the car with just clutching, you have give it some "gas".
Whereas on a cold start, the idle is high, and so you can just drive out of your driveway with just the clutch, and then accelerate off like normal.

So what I'm saying is, even with the engine not up to temperature, the idle drops quite soon.
( but it's been about 1 week since I've dríven the car, so I might have forgot, but again.. something just doesn't feel right)

[JBT]

So what I'm saying is, even with the engine not up to temperature, the idle drops quite soon.

That's normal. The high (cold) idle only lasts for about one minute if the car is dríven straight away.

Otherwise, it looks like you may have fixed it.

[Okibi]

Could it be that he's burned part of the cat out, hence the different exhaust tone?

I think I did the same to mine when I had similar problems, still haven't had time to rip it out and take a look.

[philz]

So what I'm saying is, even with the engine not up to temperature, the idle drops quite soon.

That's normal. The high (cold) idle only lasts for about one minute if the car is dríven straight away.
Otherwise, it looks like you may have fixed it.

Hopefully so! Cheers for your on going help JBT

Could it be that he's burned part of the cat out, hence the different exhaust tone?

I think I did the same to mine when I had similar problems, still haven't had time to rip it out and take a look.

If it is burnt, are there any down sides?

There is a more stronger exhaust smell compared to before.

[bruce]

Give it time for the smell to clear. Cat and mufflers have probably had a bit of fuel through them.

[philz]

Alright it looks like we are back to where we have started.

But this time I know what to do to fix it.

Started the car, car is fine, drive it around, all good.

About 1-2hrs later go to get some food, start it up misfires, open up the bonnet, make sure its still misfiring, take out number 4 lead, plug it back in, we are back in business, drive it about 5mins, turn it off, get food, start it up again drive home no problems.

So about 1hr later I go start the car again, it misfires, this time I take out the one next to number 4, which is 1, plug it back in, it stops misfiring.

So, what I have been doing to fix this is taking out one plug at the coilpack, and then replacing it back, then it stops misfiring.

[JBT]

D'OH

IIRC, cylinders 1&4 run off one coil pack and 2&3 off the other. So, the 1/4 coil pack is dodgy or you have some lead terminal issues with that coil pack. If you swap coil packs and the problem migrates to 2/3 then it confirms the coil pack is dodgy.

[philz]

Alright sweet, after reading your post JBT, went out to start the car.

Misfire (woo!), take out 2 and 3, no spark whatsoever.

Take out 4, which makes the spark jump to the close metal, which proceeds to fire out to 2 and 3, then the car works again.

So looks like 2/3 are dead coilpacks? OR the leads connecting up the coilpacks dead?