High NOx fails emissions but no codes - 1997 850 R

[gmh]

Great to hear! Obviously the CO is good, but the others are approaching the limit.... is that about normal, or are they borderline? I'm not from an emissions testing state, so I don't have any idea what is typical.


I wish I had my OG 850 T-5 emissions printout for comparison. I looked for it in my posts here but I don't think I uploaded it. Short answer, I don't know.

FYI, I found a couple of old emissions reports, one from October 2017 and another the last time it passed in 2023. The NOx was high in 2023 too.

[MoVolvos]

It's not the end of the world if it is the cat. I can offer it for sale. Several cities (their counties) do no emissions testing, like Pueblo, Colorado Springs, Durango, Aspen(!), Vail(!), and Telluride(!), so there is a fairly close set (by western US state standards) of potential buyers. GMH offered it to me for nothing, literally, and I gave him a token amount of USD. It would be nice to have for my son who is 16 now, but there's a good chance he's getting a 2009 Cadillac from his grandparents on the other family side. Or I can just tell him he has a free car... until the temp tags expire in mid February. dad humor

He's still on his learner's permit either way until he logs xx hours, and that ain't happening with my VW because it's manual and he's shown 0 interest in learning. I've taken him out 3 times for a few minutes each time (parking lot), and after that I left it up to him to come to me to ask for this and he hasn't. You can lead a horse to water, etc...

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When I taught my kids and others, before doing any street driving I would have the driver do circles left and right in the parking lot with their eyes closed. They will start by not giving it gas as the car should move. They then will be asked to increase and decrease the speed as they spin so they can feel the forces on their body and steering. Next is acceleration and quick stops to get a feel what the car is capable of. If a shop cart is available it will be used as the stopping point, not in front of the car of course. The trick is they can't use the brakes till I tell them to. Again, getting to know the forces of braking and capability of the car. Lastly, left, right and U turns. Fun fun!
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[abscate]

Am I the only one who noticed the inspection limits changed on those reports? What gives there?

[scot850]

Yes a good point Abscate. The NoX limit changed from 1.5 to 2.0. Perhaps the limit was set wrong for a car of it's age first time around. Would not be the first time an inspector did not know the rules for vehicle age related values.

Either way, take the win and now thanks to the doctor's attention to detail it has you prep'd for the next time.

Neil.

[gmh]

Yes a good point Abscate. The NoX limit changed from 1.5 to 2.0. Perhaps the limit was set wrong for a car of it's age first time around. Would not be the first time an inspector did not know the rules for vehicle age related values.

Either way, take the win and now thanks to the doctor's attention to detail it has you prep'd for the next time.

Neil.

Thanks Neil. From my experience, the inspectors have no input in the testing process. The VIN is entered and the computer is plugged into the obd2 of the car. An employee drives the car onto rollers (front wheels for the 850) and stays in the car to vary the engine rpms as directed by the computer. A search did reveal that Colorado lowered the limits for HC and NOx beginning 1/1/2022.

The very low NOx level on the 2017 test report led me to search for other such reports I might have saved. I found the attached report from November 2019 and as you can see, the NOx level is almost at the limit. So what could have happened in that 2 year window? I believe the answer is that I had the valves replaced by an indie Volvo Specialist in September or October 2019 after the car suffered a burnt valve. I never had occasion to search for vacuum leaks as the car always passed emissions, but I would bet there is a small one that resulted from that repair.