i have a 91 civic si hatch and i was racing an accord a couple days ago and when i shifted into fourth gear while we were racing my check engine light came on and i don't know why i didn't miss shift or anything and my car is running fine i am lookin for any ideas of what it might be or easy ways to find out what it is.

 

its telling you not to street race

but i dont know what it could have been

 

What's the code? That would be the first place to start. Maybe it was code 77: don't street race . Seriously though, if you read the number of times your ECU flashes you can see what the code was, you can then check it against the list in the FAQ.