I need help, I just failed emmisions a week ago. I have a 91 350 with just k&n and flowmaster exhaust. The car only has 73,000 miles on it. I failed the NOX part of the test which is the the first test out of the two. I almost passed but wasnt close enough for them to let me pass through. What do I need to do to pass the emmsions test. Havent got a tune up for a year and a half, I think that may be part of it what do you guys think.

 

I think you sort of answered your question yourself. Have your car in tune and nice and warm before an emissions check.

 

Another thing to do besides a tune up is retard the timing, clean air filters, and if that doesn't work, new cats.

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92 Camaro Z28
350 TPI
Dart Iron Eagle heads
10.5:1 cr
Lunati L54779 cam
52mm throttle body
Ported plenum
Home made AFPR ($2)
1 5/8 shorty headers
Ram air
255 lph Holley fuel pump
2.5 inch TRUE DUAL exhaust (no cats)
Flowmaster mufflers
4.10 gears
700R4 w/2000 stall
100HP nitrous
Best time before any of these mods:
15.1 @ 91.9
Best time after mods:
12.60 @ 108.3
That is at high alt.
5600 feet Morrison, Colorado Bandimere Speedway

 

91,

During the tuneup don't forget the o2 sensor! Two of my cars have failed e-check because of this. A year and 1/2 is plenty of time for one to go bad. Also, make sure you change the fuel filter, it gets overlooked too often during a tune-up.

Barry Izold
89 T/A, GTA
Modded 350/T-5