What diagnostics did he perform and what was the result?

What's a "combustion flush"?

I take it you didn't witness any of this?

I could have probably gotten it to pass by just driving it around the block hard a couple of times and then running the test as quickly as possible

In CA we have a "tire dry test", which the tech can run on a wet day. As an experiment, I intentionally took my car in on a rainy day in January '01 and asked the tech to run the tire dry test, which is 30-60 seconds on the rollers with no load at about 25 MPH. He did this and then went right into the first test, which is 1550 and the HC was 87 ppm versus 121 two years prior against a limit of 141. O2 dropped from 0.4% to 0.0% so all the O2 was being used for oxidation by the catalyst. I attribute the reduction directly to the tire dry test which heated up the catalyst.

The HC limit for my car dropped to 116 in '03 and after barely making the cut at 113/.1% O2, my new knowledge about the ignition map got me down to 73/0.05 O2 in '05, and I don't see how it can get any lower.

Your first test was a marginal failure and was probably just a conditioning issue, but the car still has little margin.

You're probably going to have to go through this drill every time. Or you can work on your spark advance map and properly condition the car yourself, and probably pass on the first try, which is what this guy might have done given the substantial reduction in NOx, which was exactly the response from my engine, too.

Duke