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Update on 940 Wagon failing smog for oxides of nitrogen - passed after replacing spark plugs 900 1993

Well, after replacing the spark plugs and running a few tanks with fuel treatment, the car passed the re-test of the Maryland emmissions test. It previousely failed the NOx levels by a little. I pulled the plugs and discovered VOLVO plugs with gaps twice the spec (spec is 0.028" - 0.032"). The plugs I pulled were neither badly worn nor did they have the "bad" kind of resdue on them. Also, I have passed Massachusetts emmissions last September with flying colors on these very plugs. Mass NOx limits are similar from what I could gather from paperwork I have. Not sure what to make of any of this, but seemingly, changing the plugs to properly gapped ones did the trick.

Thanks to all that gave me great insight into this issue. I now know more about causes of high NOx levels than I ever did :)


Best to all.
--
Vladimir. '98 S70 base, 5-speed manual - his, '93 945 - hers,






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New Update on 940 Wagon failing smog for oxides of nitrogen - passed after replacing spark plugs [900][1993]
posted by  Vladimir subscriber  on Tue Aug 10 09:34 CST 2004 >


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