B2300 -- 2003 --- 145000 miles --- 2.3 engine.
#1 cyl. won't fire!!
timing marks line up.
good compression.
injector is good.
coil pack is good.
wires are good.
cam is good.
lifters are good.
cyl.leak down 14%
no ECU codes.
can switch everything to #3 from #1 and 3 will fire.
Mazda tech has no ideas.
HELP!! anyone have this problem ----- Thanks

 

Could be dirty fuel injectors or leaking fuel injector seals. Put some fuel system cleaner in it (should have been done 1-2 times a year). i'm quite sure he didn't move #1 injector to #3!
Injectors still good @ 145,000 miles is hard to digest, especially if plugs and ignition coils have been changed (if you never have changed them, do it).
You should also check fuel pressure (and fuel pressure regulator) as both get weak over time.
However, if only on 1 cylinder I am tending to lean to the injector and/or seal.

 

I agree with Noggin.

One more thing: It is not likely that the mechanic changed "everything" over from #1 to #3. Maybe he changed over the plugs and maybe he changed over the wires. But he cannot have changed anything on the coil pack. Coil packs can short out internally. Since the error remained at #1 it is likely that the #1 wire or the coil pack are causing the miss.