My S-10 will not pass due to hign nox readings. I was told to check the egr valve. I was then informed that the 2.2 was not equiped with an egr valve.
A smog technician believed that the high nox reading may be the result of high carbon buildup on the pistons. Any information related to this or any other possable problems for high nox readings along with advice on how to resolve the problem would be appreciated.