[EclipseRST]

1st thru 4th cylinders look like this:

While I'm assuming you are at TDC in cyl #1, the 1st cyl is on combustion/power stroke, the 2nd cyl is on the compression stroke, the 3rd cyl is on exhaust stroke and 4th cyl is on intake/gas stroke. So there for it fires in the certain cylinder each time the crank rotates 180 degrees from TDC as 1-2-4-3-1-2-4-3...

Since 1 & 4 cyl and 2 & 3 cyl are linked together there is no way to have the firing order 1-2-3-4 because when cyl 2 is on the combustion stroke, cyl 3 is going down with it. So cyl 1 & 4 move up and down at the same time/speed and cyl 2 & 3 move up and down at the same time/speed. (I put this in cause I know someone will end up asking why cant it fire 1-2-3-4)

So say you have the car at TDC in cyl #1, rotate the crank 180 degrees and you have combustion on cyl #2, rotate it another 180 degrees and you are on combustion stroke in cyl #4, rotate it another 180 degrees and you are on combustion stroke in cyl #3, then when you rotate it another 180 you are back at TDC and have combustion in cyl #1.

Sorry if that throws anyone off, its how I learned in school and I dont have a diagram for it. If you want me to go through and explain it better or if Kevin can do a better job go right ahead.

I look around for a diagram and see if I can find one somewhere on the net.