Barely passed emissions test. High HC.

c good

Original poster
Member
Dec 8, 2011
521
Hi All,

My Envoy just squeeked by. Here are the numbers
15mph test
CO 44 ppm Measured. Max is 45. Average is 4
CO .11 % Measured. Max is .57 Average is .01
NO 112ppm Measured. Max is 482 Aveerage is 25

25mph test
HC 12 ppm Measured. Max is 28 Average is 4
CO .00ppm Measured. Max is .70 Average is .01
NO 8 ppm Measured. Max is 735 Average is 24

So, it passes at higher speed. Lazy O2 sensors? Weak catalytic converter? It has all new, correct AC Delco plugs, new air filter, cleaned throttle body.
No codes are stored and it runs great. I average around 18 mpg on the freeway at speeds of 75 MPH, closer to 19-20 mpg when I'm going 65 MPH. Any ideas on this? Thanks for any input. c good
 

CaptainXL

Member
Dec 4, 2011
2,445
Looks like maybe dirty fuel injectors. Just a smidge.

Try BG 44K. It cleans everything from fuel pump sensor to fuel filter to catalytic converter.
 

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