took my car to get emissions it fail on the NOx ppm it read 1152 and whats allowed is 773. my car is a 92 sc300. i asked the guy what it means and he said its not burn enough fuel and someone else said that it didnt have a comp so he would have to go through the whole car to find the prob. and a third person told me tha it means it has to much carbon build up.....any ideas?