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12-22-2002, 11:06 AM
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Got big-block?
 
Join Date: Jul 2000
Location: Austin, Texas
Posts: 2,453
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Failed emissions test....NOX too high...??s
My '93 failed the Dallas County sniffer test Friday. My NOX levels were too high. Tech said that is usually an indication of too hot of a combustion chamber. Probable EGR failure. Might also be too lean.
I'm going back for a retest on Monday. I've already pulled the intake off and cleaned EGR ports as well as installed a new EGR valve and EGR solenoid, and new AC spark plugs. Reset timing back to factory spec of TDC. Anything else I can do? Was told might be a plugged catalytic converter causing the high chamber temps. Is my open element air filter pulling in too much air? Any ideas? Thanks for the help, SC
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'68 CST SWB factory 396/T400 buddy buckets, a/c, ps, pb '72 Corvette convertible 454/4spd/ac, ps, pb '73 GMC Sierra Grande short wide 454/T400 ps, pb, ac '77 K5 Blazer black on red, 350/T350/NP205 ps, pb, ac all original '78 GMC Sierra Classic short wide 454/T400 ps, pb, ac '72 GMC Sprint SP454. 1 of 38 built. '73 GMC Sprint SP454. 1 of 71 built. '75 GMC Sprint SP454. 1 of 25 built. SOLD! '72 GMC K25 4x4 468/4L80e/NP205 build thread http://67-72chevytrucks.com/vboard/s...23#post4324423 SOLD!'55 Chevy gasser 496/4spd build thread http://67-72chevytrucks.com/vboard/s...96#post4324396 |
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