I just had a new header installed and the cat removed on a 90 gxl. i know that the lights coming on because the cat was removed but does anyone have a way to get it to stay off? it only comes on after about 5 minutes of highway driving. in town it doesnt turn on at all.

 

Figure out what the trouble code is: http://www.johnr.com/cpucodes.html.

There is no code for a removed cat. The computer system is way too simplistic for that.

 

You probably broke your o2 sensor when you installed your header!
Check your code and if it o2 sensor get a new one

Eric