What happened?
 

OK, so I was driving the 8 at around 80mph when the engine management light started flashing. It went away after a few seconds. A couple of minutes lates, it started flashing again, this also lasted a few secounds. After another minute or so, I started losing power, the car was struggling to retain revs. I then got a solid cel light, and the revs wouldn't go above 4000 (safety feature I guess).

I pulled onto an off-ramp, and the car stalled. I started it again (whilst still rolling) and kept it going whilst I found a place to park. During this time, the car was still struggling to maintain (even low) revs, and would approach a stall if I accellerated quickly.

After stopping, I got out, and could smell burning (I think it was coming from the engine bay). I couldn't see anything abnormal under the hood, but it was too dark to see properly anyway, so I just checked that there was oil in it.

Anyway, I switched it back on, and struggled home slowly (with a solid cel warning light). I'm gonna have a look at it in the morning, it's too dark now. Unfortunately, I've got no way of reading the code. I've got a Goodbox, but it's sat on my desk.


Any ideas as to what's wrong with it?

The flashing cell was a misfire.. but the solid could be a number of things. Try to take it to an autozone to get the codes read.

It's under warranty so I'll book it in at Mazda, but that'll probably take a week or so. I've got a job interview in a couple of days, and its quite far away. Looks like I might have to go in a rental. :(

Sounds like igntion coils.

^ Yeah, thats what I suspected. Thanks guys.

I think its your cat, I had the same thing happen to me

^ Oh. Well I'll update the thread when I find out. Whatever it is, its a PITA. These things always happen at the most inconvenient moments.

Maybe if I do the brake pedal reset, it'll all go away?! :yesnod:

Please give info about the vehicle. Year, transmission, mileage, original engine? Last coil, wire & plugs.

Its a 2005 MT, GT spec. Original engine on around 44000 miles.
I had the plugs changed a few months ago.
I don't think the coils / wires have ever been replaced, but I'm the second owner, so I can't be sure.

Another thing I just remembered, do u have a MS or AEM cai?

Replace the coils then.

Nope. Stock intake. Still think it's the cat? If it is, it's a good job i'm under warranty.

Dude your coils are past due there is no magic way for them to start working normally again. And yea the car will run with bad coils, they will even test good most times.

Common misfire no big deal.

You went into limp mode because you abused it.

All you had to do was clear the code and drive normally... unless you want a ticket.

Mazda says one of the coils is completely f*@%ed, so they're replacing them all.
They're gonna test the cat after, to see if that's damaged as well.

Hopefully they are covering the coils under warranty, because otherwise they are going to rape you on cost. Coils are $140 from vendors here (for the set, $35 each), most dealers mark them up to $200-$300 just for the parts, and add $100-$200 for the labor.


Buy yeah, sounds like a classic case of coil failure (misfires, stumbling) which directly led to getting the cat clogged (inability to rev, maintain speed, burning smell, extra heat)

Order a set of plugs and plug wires and change them out as well. They should also be replaced every 30k, and likely weren't if the coils weren't either. Failing coils can also really foul up the plugs, so if they were changed before, they might need it now. $80 for all 4 plugs from several vendors here, $60 for wires. Easy quick swap doing it yourself.

Also, if you don't quite feel the car back to normal, seems like it runs too rich or lean, your mileage doesn't get back to where it was, etc...they you may have also cooked your O2 sensor to the point of failing. ($260 for the front O2 from Mazmart)

Simple items failing snowball into a lot more failing in VERY short order on this car. One of the main reasons we advocate getting all ignition parts replaced every 30,000 miles



This exact sequence is what happened to me btw. Failing coil fouled plugs, cooked the cat, clogged it, couldn't maintain speed, replaced the ignition stuff myself, cat replaced under warranty, never went back to normal, 8 months later figure out that the O2 sensor burnt from the excess heat and was constantly degrading.

I always keep a set of funds in a third saving account I have. It's enough to get a clutch, ignition kit, brakes, and a set of two tires just in case.

Thanks for the info. THe coils are being replaced under warranty. I replaced the plugs recently, and I assume that they've checked them as well.

The main thing that irritates me, is that the dealership only gets things done if I constantly phone them. Otherwise, they just let the car sit there.

Update (so far)-

Being replaced under warranty:

4 coils (3 are gone, but they're replacing them all)
O2 sensor
Cat

Needs replacing, not under warranty:

Rear box (cat back)

They are telling you you need to replace the exhaust from the cat back?

^ why is that surprising Easy? The Cat-back (aka back box) is typically a 'wear & tear' non-warranty item. The Cat is of course typically a covered component.

I understand they are trying to make money.
But I want to know the reason, in their words, why the exhaust has gone bad. And what is bad on the exhaust.
Tell them you'll take the muffler home an have it cut in half to determine the issue with the muffler.