wHAT POSSIBLE CUASES FOR A CHECK ENGINE LIGHT?

97 Malibu 3.1 with 75k miles. I did my injectors a couple of weeks ago but hardly drove it, maybe 35 miles in all, and the check engine light came on. I have run into this on my Z28 with a bad smog pump, and a loose gas cap, but what other things set it off?

Tough question. The possibilities are endless. Best thing to do is take it to a place where they'll pull codes for free, like autozone. Last time I replaced injectors on one of my buddy's cars, it took a day or two for the check engine light to go away after the new injectors were in. Don't know what else to tell you besides to get codes read.

When's the last time you replaced the air filter?

Air filter has only 3k miles on it or so. 0 2 sensor maybe. Would be nice if it just disappeared on it's own but I don't have that kind of luck:) Wil see about a cheap option for getting codes read. Thanks guys.

97 Malibu 3.1 with 75k miles. I did my injectors a couple of weeks ago but hardly drove it, maybe 35 miles in all, and the check engine light came on. I have run into this on my Z28 with a bad smog pump, and a loose gas cap, but what other things set it off?

There are close to 100 codes that can be stored by the PCM.
Best bet is to have the code pulled. This will determine what circuit or componant may be causing your SES light to come on.
Causes for a SES light....sensor failure, controlled parameter out of specs, numerous wiring issues....

And today the check engine light is off. is it possible that the ECU was confused by going from the old f@cked up injectors to the rebuilds?

yeah. I don't know if it was "confused" per se, but It sometimes can take a while for it to know that there isn't anything wrong anymore.

Go to AutoZone, they check for free.