Vitor Posted December 21, 2005 Report Share Posted December 21, 2005 About 6 months ago, my daughter took my 99 S80 T6 and traded in her 96 850 NA (What a deal I got here).The 850 is parked most of the time but I have to drive it for about 5 min everyday, not enough to get it up to working temp.About a month ago I took it for the smog inspection and it failed because the HC readings were 13 PPM over the limit. No problem, a new set of plugs (they had some black deposits on the insulator) and a good 30 min drive on the freeway and I went back to the inspection station. I replaced the plugs with Bosch platinum.The HC went to about 12 PPM, CO almost nothing, CO2 almost 15%, NOX went to 2,500 PPM. My car was labeled "Gross polluter".I replaced the plugs with regular plugs but the Nox is still the same. No codes, engine runs fine.Any ideas what's going on?Do I have carbon buildup in the combustion chambers?Is the 3 way cat gone? Link to comment Share on other sites More sharing options...
WhiteT5 Posted December 21, 2005 Report Share Posted December 21, 2005 My guess would be carbon build-up somewhere or maybe the car needs a new front o2 sensor. If the cat were dead, all of your readings would be high since it is a 3-way converter and it works to reduce the 3 major pollutants produced by an internal combustion engine. What sort of gas mileage are you seeing? Link to comment Share on other sites More sharing options...
Guest Guest_850 glt_* Posted December 22, 2005 Report Share Posted December 22, 2005 Maybe related..I had the same issue with my miata..Turned out I had an exhaust gasket leak before the cat. The mix of gasses has to be just right for everything to work properly in the cat. There are 3 different chemical reactions going on in there and they all influence each other.After I replaced my forward cat seal and backed off my timing to 5 degrees ( not sure this is even possible in a volvo. ) Everything passed fine.Oh, I also ran the car hard to heat up the cat before the test. And kept the car running before the test.Since you are now a gross polluter, you'll probably have to go to referree stations.. It's really not so bad, since it's actually _cheaper_ than most other places ( $30 + 8 for cert )... They just check more things than the normal place.Jeff Link to comment Share on other sites More sharing options...
Vitor Posted December 22, 2005 Author Report Share Posted December 22, 2005 I have no idea on the MPG, I only drive it to test the parts I rebuild.For those familiar with the 3 way cat and smog inspections.The Nox reduction takes place in the front of the 3 way cat, Nox is a result of high temperatures in the combustion chamber due to high compression or ???????????High compression may result from excessive carbon buildup in the combustion chamber or carbon deposits acting as a glow plug?????In the past the temperatures were reduced by the EGR valve introducing exhaust gas to the intake. There is no EGR valve in this car. Link to comment Share on other sites More sharing options...
shurgen Posted December 22, 2005 Report Share Posted December 22, 2005 There is a seafoam thread on the main page of this forum. If you have a lot of carbon build-up inside, seafoam should help get rid of it. If you get tired of reading the whole thread , let me know, I'll write you step by step how to perform the cleaning using the vacuum tree.Alex Link to comment Share on other sites More sharing options...
the underlørd Posted December 22, 2005 Report Share Posted December 22, 2005 if you only drive it to test the ABS units, why even register it? drive it around the block, and that's it? Link to comment Share on other sites More sharing options...
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