help! my miata won't start.

Hey, My miata wont start and I dont know why. the engine turns over and it gets air, it has gas and the battery is fine. I tried an inline spaktester in on the first sparkplug and it didn't go off... I dont know what I should be looking at for the problem. it's definately an ignition problem, but I dont know where to start. help me please!

ASSUMING THAT THIS IS A 1990-2005 - they've made "Miatas" for over 30 years.

Check that the main relay is turning on, it's a common failure point and it'll go like this - car is working fine until one day it just doesn't wake up. You should have 12v at the injectors on one of the two wires with the ignition on. The color of that wire will depend on what year the car is, but there are only two so the process of elimination is short.

If you have 12v there, please give us a little more info.

In reply to Keith Tanner :

sorry, I should have added that it is a 1994 na miata, and thanks for a starting point.

1994 will have 12v on wires that are white with a red stripe with the ignition on. They're everywhere.

I have done a bit more poking around, looking at the ECU, the fuses and the ignition coil packs and they all are fine. I have no idea what to do now... we noticed that when you first try to start the engine it has one quick spark in each of the spark plugs, but then nothing else, it is this way across all four of them. what should I check next?

In reply to CSmith :

Not really certain, but I know Keith will know.  Could it be a failed cam angle sensor?  I know once an engine can't measure timing, it will just not run or even fire.  That's the next thing I can think of that "might" be the cause this that you have not checked.  Do you have a factory manual?  They usually have pretty good troubleshooting sections.  Sadly I sold my factory 92 Miata manual long ago.

In reply to AnthonyGS :

thanks for the next place to look, I'll check that out tomorrow :)

You can trigger the check engine codes in a 94 by following this guide.

On a 94, there's a good chance that it's the igniter if you're throwing a code 01..

So, you are seeing 12v on those white/red wires with the ignition on? A failed ignition relay looks completely normal, you can't test it by looking at it. If you can pull codes from the ECU, you've got a functioning main relay.

Broken wires at the CAS are not unusual, which means no engine speed signal. A failure doesn't usually present quite like this, but it's possible. Definitely pull codes.

In reply to Keith Tanner :

yes, I am showing 12 volts on those white/red wires. Also, I have no idea how I should pull codes from this... 

In reply to WonkoTheSane :

thank you for this. I will be using it.

news update, I turned the car to on and started checking wires to the ECU and there is no power going through those wires. I had thought that the ECU was the problem but now it might just be the wires, this makes me happy because getting a new bpe8 ECU is about $100-$120 but new wires will be significantly less. this leads me to my question, where should I check the wires? could it be a fuse? the radio and speakers still work as well as lights on the dash. I was not able to get a fault code from connecting the ground and ten like it said, could that be because the ECU isn't getting power?

Yeah, you'll only be able to get a code if the ECU is alive to tell it.  I believe there is an ECU fuse under the dash (not the engine bay fuse block), but I might have them confused.. That's going from memory, not looking at my 94 :)

I don't have my wiring diagrams handy, but the next step is to find all the things that are dead and trace them back to the common point. I was working off memory with that ignition wire, this could still be a main relay.

In reply to Keith Tanner :

ok, i'll check and see what else is dead, i didn't notice anything else but i'll look again.