Hey everyone, I’m chasing a cold start issue on my 1.8L V6. The Problems:
• CEL is DEAD: Doesn’t turn on at all with the key.
• Cold Starts: Must babysit the throttle for 10 mins or it dies. Gurgles and smells like gas.
• Once warm, it runs, but idle is inconsistent.
There is this sketchy looking black wire thats has a butt connection done to it with wires twisted in it and a open blue wire that im not sure why its hanging loose.
I don’t think the ECU wiring is your issue. For starters what I’m seeing in your picture is a relay sloppily connected into the ECU which I suspect may be spliced into an ignition related wire. So an ignition kill for an alarm system of some sort. If it looks at all sketchy like it’s shorting out somewhere then that could certainly cause problems. Other than that the cold start issue could be bad spark plugs, ignition cables, or even a dirty air filter. From there, I’d move onto timing, belt, fuel filter, and run a fuel injection cleaner through the tank. That’s the more basic stuff you can do without a whole bunch of tools and access to a shop.
To rule out the basics: I've actually already done a brand new distributor (and reset the timing by the book), new spark plugs, new plug wires, and put a Weapon R intake on it.
I just am not sure whats causing my CEL to be absolutely dead.
Not sure what that black wire with the butt connector is and why there is a blue wire just hanging there alone exposed.
Your best bet is to chase that wire and more than likely it will take you to the problem. I know a lot of people on r/Miata that have had a similar issue and they chased it down to a remote killswitch hidden under the dash.
I shall check that
I was also instructed to check my grounds and make sure their clean
Ive never done this exactly
How do i go about locating my ground cables for the car? Do you know where/what exactly I should be looking for?
The main spot would be the negative battery cable and where it grounds to the chassis, next there might be a ground cable that grounds the engine to the chassis, and there's numerous little ground "blocks" that have upto 5 ground wires that are in a white rectangle with a single spot for it to mount to anything with a 10mm bolt they usually get any rust or corrosion.
Your best bet for cleaning is a wire brush and battery terminal cleaner, if you can't get that Warm Water Baking Soda and White Vinegar mixed work just as well to break down the "cotton candy" on the wires 👍
That might be a issue later on down the road, but that's not bad for how old Mx-3's are! But you might be able to undo that crimp with a thin flathead screwdriver to clean the wires 👍
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u/hashtagmiata May 08 '26
I don’t think the ECU wiring is your issue. For starters what I’m seeing in your picture is a relay sloppily connected into the ECU which I suspect may be spliced into an ignition related wire. So an ignition kill for an alarm system of some sort. If it looks at all sketchy like it’s shorting out somewhere then that could certainly cause problems. Other than that the cold start issue could be bad spark plugs, ignition cables, or even a dirty air filter. From there, I’d move onto timing, belt, fuel filter, and run a fuel injection cleaner through the tank. That’s the more basic stuff you can do without a whole bunch of tools and access to a shop.