Emissions Question

I have an 88 240 wagon. 321K miles. Every two years in AZ I get the emissions tested, and I fail. Alway NOX that fails. I get a new catalytic converter, and it passes. Any suggestions as to how I can make it pass two years from now?

Thanks!

John

Reply to
John von Colditz
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That's odd, my mom's 245 had its catalytic converter crumble inside and it has continued to pass the emissions inspection in WA with plenty of room to spare.

I've heard of some blocking off the ignition advance vacuum line to reduce NOX, you might try that.

Reply to
James Sweet

Obviously the Engine is not working correctly, have you had it checked against the specifications from Volvo (for CO, CO2, HCs, NO, O2 etc)?

Being within national vehicle test standards does not necessarily mean the engine is working properly. You need to get to the bottom of the problem. for example, if your cat keeps going you may have a problem with overfueling, showing up as a high HC reading.

-- Tony

Reply to
Tony

NOx emissions happen at elevated temperatures. Unlike most forms of pollution, which decrease at higher temperatures, NOx actually increases.

I have an 82 240 wagon that passes just fine here in Oregon, but NOx is too high if I have driven it for a long period and it is running at the higher temperatures that come with long driving. If I have driven it only

6 miles at moderate speeds, it passes just fine.

By their own admission at our state testing facility, it is a bit of a problem with NOx testing. People try to heat up their cars as much as possible before going through the test, in order to reduce hydrocarbon, CO, and others, which go down with high temperatures. Yet, that effort to get the engine hot may result in excess NOx emissions.

I don't know about AZ, but here in Oregon the test is free of charge if you aren't trying to do a renewal. If that is true there, what I would do is have your car tested after a much shorter distance of driving than what you have done in the past.

My guess is that the distance you drive to the testing facility is simply too far, and the engine is too hot when you get there. On the other hand, when you had the converter replaced, I'll bet you drove less distance to the testing facility, and the engine was at a more normal operating temperature then.

If there were a serious problem with the engine tuning, it would most certainly show up in the other exhaust components.

Certainly, you should check for engine problems, but if that doesn't turn up anything, don't be surprised. Possibly a radiator that is starting to have a few problems might show up in elevated engine temperature, but sometimes it is just a matter of distance driven.

Here in Oregon, last year, they didn't test cars of the age of mine for NOx. Apparently they have decided there isn't that much that can be done about engines of that age that are running a bit too hot, because distance driven prior to the test is really the primary problem with causing NOx formation.

Reply to
gl4317

snipped-for-privacy@yahoo.com formulated on Saturday :

Thanks for the suggestion! In AZ you pay about $28 for the testing, and you get one free retest. I live about a mile from the testing facility, so it is not too hot when I get there! I ended up going to Volvo. It was about $100 more to have them do the cat, but it is guaranteed for 5 years...

Reply to
John von Colditz

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