OBDI 101: when will the check engine light come on?

[BerniniCaCO3]

My new engine build is not running as smoothly as I'd hoped.
Now, I haven't actually touched the engine proper in the past week and a half-- I decided to replace fuel injectors, and mess with adding dash gauges, and finally do that heater core, so I've just been avoiding serious engine diagnostics.

I still haven't done elementary things like:
-vacuum pressure?
-rpms @ idle?
-oil pressure, with proper mechanical gauge? (and not just assume that because the idiot light is on at idle, I've got 5.99psi @ idle).
-fuel pressure?
-check for spark? Could I have damaged a spark plug wire? (christmas tree still the best way, or, resistance test across each wire?)

But anyway. I'm going to do those good things next weekend.
I was listening to audio tracks of missfires versus smooth engines, I think my build might be missing (I know most of you would recognize a missfire in an instant: I just haven't been doing this long at all).

Would a check engine light necessarily trigger with a continuous missfire?
If it most definitely would on a missfire, and given that I have no check engine light, then I can conclude that that's not a problem for me.

But if the check engine light only triggers on very major stumbles, then I might still have a missfire, and codes waiting patiently in the computer for me to pull and read?

[1980c10]

If you have a test light you can use it to ground out a cylinder and diagnose which is miss fire. Hook the test light up to a ground then stick the sharp end into one spark plug boot at a time this will ground out that cylinder and you will hear a change in the way the engine idles. If you get to one and it doesn't change anything when you ground it that is likely a dead cylinder. The really only helps check for fouled plugs though a miss could be caused by other things and/or be to intermittent to pick up.

[1990LTD]

http://sbftech.com/index.php/topic,2471.0.htm

....the following failures or codes are the only ones that would trigger the CEL/MIL to turn on for the time the failure condition is present, once the failure is not present, the CEL will turn off:

CIRCUIT CODES
ACT 54, 64
ECT 51, 61
BP/MAP 22
MAF 26, 56, 66
TPS 23, 53, 63
EVP 31, 32, 34, 35
HEGO(1) 41, 91, 42, 92
(1) Based on a "lean-rich" switching counter timer function.

Intermittent codes will only trigger the CEL during the time the failure condition is present. Any other circuit failures may be present, affecting driveability and/or performance, but not cause the CEL to turn on....and can only be identified/retrieved via the self-test routines. Another case are the failures that are not logged in memory, but are present during engine operation.....any failure code that doesn't have a "M" = memory, continuous notation, but any of the others, falls under that category....as you can check at http://sbftech.com/index.php/topic,849.0.html .

[86VickyLX]

http://sbftech.com/index.php/topic,2471.0.htm

That pretty much covers it. Good job Josh.

[gadget73]

I wonder how many times over the years I should have had a CEL. Prior to 1989, most panthers did not have one.

[1990LTD]

That pretty much covers it. Good job Josh.

I use that and fordfuelinjection.com for everything EEC-IV related. Reading about strategies and long-term learning and blah blah blah gets old but it has really helped me.