278,000
1988 745 Turbo (all stock)

at last state inspection, 2 yrs/25K ago, passed with ease (3.25 allowed - measured .08)
this time measured 5.99, need 3.25 or less to pass. Garage says CAT is most likely,
another thoughts why so much difference in my well maintained car?

other info
HC 2.25 allowed/measured 2.07

CO 23.74 allowed/measured 18.08

NOX 3.25 allowed/measured 5.99

CO2 656.31[]

 

to be high on only nitrous oxide isn't unusual and a new cat will probably fix it...or at least bring it to passing levels at which time you can pull the codes to see what the real problem is.

 

Maybe Bad o2 sensor?

 

wouldn't a bad o2 sensor just neglect to tell you your emissions were bad?

 

clean your flame trap.

 

Thanks, no flame trap on Turbo. Why we own Volvo's...durability dude: O2 sensor, Cat Convert
and Mitsu Turbo all have at least 160K on them. 278000 on odometer, next stop - 300K!

 

No technical Flame trap but still has a Nipple that can clog and make the Reading off.

 

you are correct about that passage getting clogged, although it is OK now I
had to use a small drill bit to ream it out in the past. Thanks.

 

I am not real familiar with the turbos. Other vehicles use egr to recycle some of the exhaust gasses. This lowers combustion temperature and reduces NOX.