I've allways heard a hot car will have fewer emissions, but that's just hear-say. Don't quote me on that because I don't even have a turbo on my little beast.
Since you have high NOx, try lowing your temp on your car add water wetter, check your plugs, wire, o2 and retard your timing a bit.superfasteddie said:Ok check this out. I have failed emissions now with the California BAR twice. I have a 1992 4g63T and The first time I failed visual as well as the sniffer. I passed CO2, HC, and failed NOX. I was triple the limit. I was running advanced timing, like 12. (don't ask) and no intercooler. The CO and HC were way low, meaning my CAT worked fine, and the engine ran really well. (?) But the REF says that NOX means high intake temp. So I spent a month replumbing vacuum lines, installing a side-mount, new TB, new EGR, etc. I had a pre-test at a local smog station and it passed everything. CO, HC, and NOX. The 15mph test was higher than the 25mph, but still passed with room for error. I made second REF appointment and it passed visual this time, but Failed NOX AGAIN!! Only this time it just failed the 15mph test, not the 25. Does anyone have a valid smog theory. I have heard get your car as hot as you can, drive the piss out of it and it will pass. Doesn't that just heat up the intake temp. Like I said, I passed the CO and HC, so the Cat works fine. So basically hot or cold? And by the way Cali sucks. Thanks