a'ight so here's the story. when i take my 89 civic dx mostly stock(intake and exhaust only) and hold the rpm for more than 3000rpm for longer than 1min i get a check engine light. cars still runs fine though and when i turn off the car and start it again its fine. the ecu says code 1 which is 02 sensor but i just replaced it. i also thought maybe it was fuel pressure so i got a new fuel filter . fuel injector diagnostic that i got from honda checked out to. new plugs and good compression.
decent gas mileage too. everything is great except for this.
pretty whacked out heh?

 

do you have a header on it? and if so where is the o2 sensor mounted at?

 

no header just stock. and the o2 sensor is straight from honda to if that matters
(i heard some aftermarket o2sensors screw up the ecu)

 

Could be a problem with your ecu. Try reseting it..... I'm assuming you know how. But if you don't know how, just take the negative terminal off your battery for a few minutes and then reconnect it, start your car and let it run for a while, then turn it off and start it again. There you go, your computer is reset.

 

Had the same problem in my car and I reseted my computer now the check engine light doesnt turn on no more, try what Onestunna recommended