1990 LT5 emissions fail

[Schrade]

Originally Posted by Franke

Thnx you for the welcome. The HC is 1.2913 and the limit is 2.000. Thats approx 1/2 the limit. CO was 15.1407 and the limit is 20.0000. So i'm good on that too. Some history on this car is that i've owned it for 5 years and the nox has been slowly creeping up. In 2007 with 53389 miles on it the nox was 1.282 and the state standard was 6.0000. In 2009 with 55294 miles on it the nox was 2.6949 and the standard was 3.5000. CO State changed the standard sometime between those two years. In May of 2011 with 55933 mi on it nox was 3.2886 and the standard was 3.5000. today it failed with 3.9183 nox.

Yup - as I guessed - WAY under limit on HC's - proportionally speaking.

You're burning just a little to hot. And it probably will NOT show in the engine coolant temp either.

Did they happen to give you the scan data, with ALL engine parameters? With THAT, some of the guys on the boards here could pinpoint the fix in short order.

If not, call the inspector, and see if they can get it for you. If not, call a speed shop. Then post it here.

Short of that, you have to reduce the burn temperature slightly somehow...