Volvo Repair: emissions for NY state inspection, fuel pressure regulator, combustion temperatures

Question
Hi,
I have a 1992 Volvo 940GL, 8 valve, 4 cyclinder, non-turbo(B230) with an A/T transmission. The milage is 129,163.
During a recent NY State emission test, the car did not pass the NOx test. The result was 2.40 gpm, the upper limit is 2.00 gpm. What can I look for and/or change inoder to bring it down?
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Thanks, Tom
>> You may not remember me, but you solved another Volvo problem that I had back in Janurary. The problem was hard starting and you suggest I inspect the fuel pressure regulator valve. That was the problem.
Thanks again.

Answer
we do not deal in emissions here so I ca not be sure I have not used a gas analyzer to check a car in years.NOX is caused by high combustion temperatures.from possible carbon build up or maybe a leaking EGR valve.I would check those 2 thinks first.for the carbon you could run an inuction cleanet that cleans carbon from cylinders and intake manifolds.