The NOx was way high , but all other factors were within spec by a far margin
What is the ignition timing supposed to be set at?
Has anyone else with an 89 (1st Gen) failed because of high NOx? and what did you do to pass?
Thanks!

 

dont know but good luck with this.

i do know that i was worried when i took my 87 rs in to get it smogged, but to my surprise it passed with ease.

 

High Nox is caused by high combustion temps, usually from late ignition timing... Do you have an Auto... they sometimes come with an EGR and yours could not be working...

As for you problem.. if everthing else is passing ok, you need to up your octane of the fuel so there is no pinging and set your timing as low as you can (to pass the ca emissions test there is only +/- 2 degrees adjustment) My base was 16 so i set it to 14 and put some octane booster in a tank full of 91...

Good LUCK!!!

 

Hey my brother had the same problem with his 90 LS with a 98 LS swap. Everything was pretty good except for the NOX. I don't remember the exact numbers but his failed in that category with flying colors, I want to say it failed by at least a thousand ppm. We went to an exhaust shop and they suggested he put on a high NOX cat. We had that installed, went back to smog it and it passed with only 14 ppm.

 

retard timing
check egr valve


Those are about the only things that effect NOx. Whoever said high temps cause it, was correct. NOx forms at temperatures over 2500*

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Nors &raquo;</TD></TR><TR><TD CLASS="quote">retard timing
check egr valve


Those are about the only things that effect NOx. Whoever said high temps cause it, was correct. NOx forms at temperatures over 2500*</TD></TR></TABLE>
Check the EGR valve. I wish you luck.