Hi there!

Here's a run through of a recent issue with my gf's '04 Mazda 3i:

She was taking off from a stop sign and the engine lost power, big poof of black smoke from exhaust which then became white and rough idle and flashing engine light. Oh, and strong gas smell.

Engine codes:
P0302 - Cylinder #2 misfire
P2196 - O2 sensor stuck rich

After removing the coils and plugs, we've noticed that cylinder 2 has a puddle of gasoline on top of the piston.

What we've done so far:
checked and switched around injectors
switched around the coils
replaced spark plugs
checked the wires from the ECU to the coils

Still, gas in cylinder #2. We would check after every step to see if the issue was still there and it was. So it couldn't be the injectors, coil packs or the wires to the coils...

We've actually removed the ECU but didn't see any erosion or burnt/melted components...

Any suggestions on what this could possibly be? I'm thinking that something must be up with the ECU, but before I go spending money on that I want to make sure all my bases are covered.

Thanks!

 

Great news!

So my dad brought the ECU into his work and had a coworker have a look. He re-soldered the connections for cylinder #2 and switched a transistor with one from another cylinder. So if the problem comes back but in a different cylinder, then it's the transistor.

My dad got the ECU home and installed it and gave the car a run and the problem seems to be gone! There's no more flooding in #2 but there's still smoke. Probably just because there's crap in the system that needs to be run through.

Thanks for having a look at my post, even though no one responded!

 

That's great news.
I couldn't respond since I did not have clue. Good job guys, and thanks for the update.