Ive failed my emissions test again and for the 5th time. The NO reading is still high. Here are the things that have been tried:

Cleaned Throttle body.
New Plugs and wires.
New catalytic converter.
New O2 sensor.
New Air Mass Meter
Flushed carbon out of engine. (some kind of vacumm system.
Retarted timing 10 deg
Pulled off the thermostat.

It seems my engine combustion is to hot.

The readings for NO dropped from 2478 to 822. Although this change might be significant it still needs to drop below 805 to pass.

HC is 26 ppm.
CO% is 0.16.

Any ideas??
Might it pass next week after driving the car for a while? I use 94 octane gas in the car. (Thats the most in my area Toronto).
Could it be the fuel pressure regulator?

Thanks in advance
Chris.

I confess that I don't know about your canadian car's emission controls, but as a suggestion, when I took my U.S. car in for New Jersey's emission controls (this is a dynamometer test, not an idle test), I flunked for excess NO. My local shop diagnosed the problem and replaced my catalytic converter and then I easily passed.

Check the intake hose for cracks or holes. Take it off and hold it up to the light. Also check for any source of a vacuum leak.
--
Bruce S. near D.C.