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still have a question. Quick background. Previously failed TX ASM2 test. Passed CO and HC but failed NOX on both high speed and low speed by more than twice the limit. Replaced the O2 sensor (it was old anyway) and the catalytic convertor. On retest I passed eveything, with a high speed NOX mewasurement of 70 ppm (Limit is 1258 ppm)and a low speed measurement of 1014 ppm (limit is 1378 ppm). I know I should just be happy and go on, but I am curious about why the low speed measurement was so high. Mainly want to think about what I may have to do next year. Car was properly warmed up for the test. Inspector did not have the external fan blowing air at the radiator. Could this have caused elevated temps at low speed affecting the NOX. I have read the posts about the Chrysler ignition system and effects on NOX. Anyone have measured experience before and after plugging the vacuum line?
BTW, as a testament to how good our Volvos are (or how marginal emissions tests are), when I inspected the old cat I discovered a PO had gutted the inside. Must have plugged up on him and instead of getting a new one just gutted it. It is interesting to know that my car passed the old 2 speed idle test, and the CO and HC portions of the ASM2 with no catalytic convertor at all.
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