You're between the proverbial rock and hard place! NOx control is accomplished with the three way catalyst. Precise fuel-air ratio control provides an exhaust gas consituency that is required for a TWC to both oxidize HC and CO and "reduce" (breakdown) NOx into nitrogen and oxygen. The oxygen molecules from disassociated NOx are also available to oxidize HC and CO.

Converter temperature is a big issue in converter efficiency, and the hotter the better. Higher EGT and higher converter temperatures can be had by retarding the ignition timing. Retarding the ignition timing also reduces peak combustion temperature, which should reduce "engine out" NOx emissions. I believe you can do this by adjusting the distributor on the 102 engine. Retard the timing at least five degrees from spec. The initial timing spec should be on the emission/tuneup decal in the engine compartment. What is it?

In CA the timing is supposed to be checked as part of the emission test and the car failed if it is not to spec. If no acceptable range is provided by the manufacturer, CA established 3 degrees advance beyond spec as the limit, with no limit on the amount of retard from spec.

All the 102 and 103 engines tend to show higher than average emissions for their year group. In CA the 103 had been identified as a "high emitter family" and they are usually on the ragged edge of HC, but NOx is not generally a problem. Unfortunately, the initial timing cannot be adjusted on the 103 engines, but the rate of advance can be slowed by varying a resistor value, which should be of help since CA tests are done on a chassis dyno at 15 and 25 MPH. Our emissions are measured in PPM, and the "cut points" are arbitrary as the cars were certified to an abolute grams per mile standard.

NY may have similar issues as the GPM cut points are probably not the same as the full EPA certification GPM limits, but are arrived at through a statistical analysis process that is essentially designed to fail an arbitrary percentage of cars.

Emission testing has as much to do with politics as it has to do with technical issues and clean air!

Duke