In Houston having trouble passing emmision. NOx going up and down, mid 900’s to mid 1200. Have replaced EGR valve, wires, plugs, cap, rotar, and cleaned complete path from the throat to EGR port. Very god vacuum and inlet to EGR from exhaust good. Running much better, more power. Good engine vac. Whats next?
oxygen sensors. wondering how many miles u have?
246,000 and no Engine light
Take a nice long road trip to make sure your car is warmed up before you get there.
Oil and filter change, then pour a full bottle of Techron Fuel System cleaner in the gas tank. Then go out for a long drive on the highway, 100 miles out, 100 miles back, and that will clean up the deposits that have developed in the engine that are causing the car not to pass the test.