1985 emissions high NOx

Hi, everyone, a friend has this Volvo which can't pass smog because of
high Nox values. What can we do to reduce the Nox emissions? I've read
high combustion temps will raise the Nox, but the EGR valve is suppose
to lower the temps, how can I test the EGR valve in his Volvo? What else
should I check for? Thanks for reading this.

 

how can I test the EGR valve in his Volvo? What else

With engine in idle, unconnect the vacuum hose to the EGR-valve from the
intake. Then suck in the hose. the engine should now stall, if it doesn't
stall, the EGR-vale is clogged and needs cleaning.
Good luck

/Erik Lidén

 

Joe;

I'm in Ontario Canada and we are required to have our vehicles
emissions tested every two years.

I last took my 1985 245 in for an e-test in October of 2004 (the last
one it will ever require since the vehicle will be over 20 years old by
the time the next required test rolls around) and on the first test, it
had a too-high value for Nox, which I fully expected since the previous
time I had it tested 2 years prior, the service tech said that the
catalytic converter was getting on in years (original that came with
vehicle)and would likely need to be replaced sometime in the next few
years.

However, the first item on the computer-generated "list of suspects" as
a result of the e-test was the oxygen sensor so they replaced that,
tested it again and that solved the problem and boy, was I delightfully
surprised.