Engine code PO304-> Which is Cylinder #4?

[JEDI]

2005 mazda3i AT, 175k miles

i replaced my sparkplugs myself last month with the same OEM iridiums that was in my car when i bought it new.

i'm on my 2nd gas tank (~500 miles).
after a stop, i accelerated like normal and the check engine light flashed a couple of times, then stayed on.

odb II scanner says PO304: Cylinder #4 Misfire.

1) which sparkplug is that? all the way on passenger's side or drivers side?
2) why would a new sparkplug cause that code?

if replacing the sparkplug doesnt fix it, then what?

 

[Railgun]

Should be drivers side (assuming lhd). If it's not plug related, could be ignition coil.

 

[Zenmervolt]

Traditionally, on an inline 4 the #4 cylinder is the one that's at the back of the engine. That is, the one that is farthest from the belts and closest to the transmission.

ZV

 

[JEDI]

Should be drivers side (assuming lhd). If it's not plug related, could be ignition coil.

thx

Traditionally, on an inline 4 the #4 cylinder is the one that's at the back of the engine. That is, the one that is farthest from the belts and closest to the transmission.
ZV

ok, farthest from the belts i understand since i know what the belts are. aka cyn #4 is drivers side.
no clue on location of transmission.

 

[Zenmervolt]

ok, farthest from the belts i understand since i know what the belts are. aka cyn #4 is drivers side.
no clue on location of transmission.

Transmission attaches to the opposite end of the engine as the belts.

I just said it that way because the engine could be mounted such that #4 was either on the driver or passenger side depending on which direction it sat in.

ZV