This is the first time I've had a truck of mine fail smog, it's an 1981 pickup. Stock 22R with 112k miles. It runs very strong and well, idles super smooth. With 33's it has more power than my 1993 22RE pickup with little 29" tires.
This truck passed smog about a year ago, but just failed for me. My standard routine is to change the oil, filters, put in fresh gas and run the hell out of it right before inspection. The HC and CO levels were both pretty low and passed(75ppm and 0.57%, respectively). The NO levels at 15mph barely passsed, but failed at 25mph. Allowed was 1380ppm, and I had 1680 ppm.
The egr seems to be functioning, and all vacuum lines seem intact and correct. Where should I start looking to solve this problem. What types of problems cause moderately high NOx levels?
Is it likely that retarding the timing could mask this problem enough?
The only odd thing about the engine I've noticed is that it has excessive crankcase pressure. When I changed the oil it resembled the morning after eating at a Tijuana taco stand.:whoops: And it has failed emmission tests on 3 other occasions since 1996, for reasons unknown.
This truck passed smog about a year ago, but just failed for me. My standard routine is to change the oil, filters, put in fresh gas and run the hell out of it right before inspection. The HC and CO levels were both pretty low and passed(75ppm and 0.57%, respectively). The NO levels at 15mph barely passsed, but failed at 25mph. Allowed was 1380ppm, and I had 1680 ppm.
The egr seems to be functioning, and all vacuum lines seem intact and correct. Where should I start looking to solve this problem. What types of problems cause moderately high NOx levels?
Is it likely that retarding the timing could mask this problem enough?
The only odd thing about the engine I've noticed is that it has excessive crankcase pressure. When I changed the oil it resembled the morning after eating at a Tijuana taco stand.:whoops: And it has failed emmission tests on 3 other occasions since 1996, for reasons unknown.
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