Smog Emissions results 1987 300E Mercedes

Hi

I have a 1987 300E live in California, however the car is from the east coast, so it is a 49 state car.

I am up for my smog / emissions test in a couple of months.

The NO have been high the last two tests. And am afraid that they might be even higher and fail the upcoming tests.

Here are the results of the last two tests. Any ideas of areas that I should look into would be a great help.

Thanks

2004 Test 15mph 2602 rpm %CO2 15.0

%O2 0.1

HC MaX 110 HC AVE 31 HC MEAS 62

CO MAX 0.71 CO AVE 0.10 CO MEAS 0.24

NO MAX 772 NO AVE 237 NO MEAS 768

25mph 1726 rpm %CO2 15.0

%O2 0.1

HC MaX 85 HC AVE 20 HC MEAS 35

CO MAX 0.59 CO AVE 0.09 CO MEAS 0.12

NO MAX 711 NO AVE 199 NO MEAS 303

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2006 Test 15mph 1735 rpm %CO2 14.4

%O2 0.9

HC MaX 110 HC AVE 31 HC MEAS 104

CO MAX 0.71 CO AVE 0.10 CO MEAS 0.20

NO MAX 772 NO AVE 237 NO MEAS 765

25mph 1729 rpm %CO2 14.4

%O2 0.4

HC MaX 85 HC AVE 20 HC MEAS 63

CO MAX 0.59 CO AVE 0.09 CO MEAS 0.16

NO MAX 711 NO AVE 199 NO MEAS 356