After replacing plugs, dist.cap, filler cap seal & distributor arm my 850 with 228000 km failed the emission test again! Problem is in the NOX rating suppose to be better than 560 my number is 2584. Anyone have a solution. Need info asap. Thanx,

Primarily: I Have never heard of any Volvo failing Ontario's emmissions test. I would do the following:

1) Carefully check that the secondary air injection system is operational. This is especially important if the mechanic fails to properly warm up the car.

2) Ensure that the Catalytic converter is not plugged, leaking or that the platinum plates have worked thier way loose. An exhaust shop will be able to perform a simple back-pressure test to confirm this.

3) Look for other symptoms such as a bad or worn O2 sensor, or engine fault codes.

4) If none of this proves to fix the problem, try changing brands of fuel, cleaning the PVC valve and having the car re-tested at another shop.

Andrew P

Toronto, Ontario, Canada

Oddsox,

Unbelievable! Really! Did you know the Ontario Drive Clean program is flawed with an incorrect database? The car is tested by weight, not engine specific. The weight of the car then falls into a specific catagory. I have had personal contact with the ministry of the environment and they readily admit the problem...sorry for the rant, anyway....has your "check engine" lamp come on? The check engine lamp is specific to emmissions and anything not working to spec that would effect the emmissions output. If the lamp has been on, then you do indeed have a problem and should have a dealer check it out. I'm guessing that your lamp has NOT been on, and your car is in fact working fine. I suspect the testing facility. My '94 850 (which is older and still with original components) passed just recently with great numbers. In fact, the numbers were better then two years ago when it was tested for the first time. Bottom line is...if your check engine lamp in not on, suspect the test.

Almost would think the cat is bad......

There is a great book from Bosch on fuel injection. It covers some information on emissions. One source of excess NOx emissions are a result of lean burn resulting in higher temperatures which cause a chemical reaction of the Nitrogen and O2 in air. This can be caused by a bad O2 sensor, or possibly a vacuum leak.

Depending on the catalyst system, a faulty cat can also cause excess NOx.

Is the EGR valve working properly? I've read if EGR is not working properly, you'll get a high Nox emission.

However, EGR problem often times would be flagged by the computer.

Cat is a good guess especially with that many miles logged.