Date:         Fri, 22 Jan 1999 15:35:41 -0800
Reply-To:     Dave Bayer <bayer@SYBASE.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Dave Bayer <bayer@SYBASE.COM>
Subject:      Re: Failed Smog Test
Comments: To: Thomas.Forhan@MAIL.HOUSE.GOV
Comments: cc: vanagon@vanagon.com

>| My 83 9pax sunroof didn't make it! Properly warmed up, at idle it has CO of
>| 2.21 pct vice the standard of 1.2 pct, and Hydrocarbons of 276 PPM, vice the
>| standard of 220 PPM.
>|
>| The engine had rings, valves and a head gasket job 15000 miles ago, and
>| fresh oil and tune up, when installed 2000 miles ago. Compression is good,
>| it doesn't burn any oil, and it runs just fine.
>|
>| I've got two months to get things in order. If I spend $150 or more (cat and
>| o2 sensor) the state will give me a waiver, but I'd rather find out what the
>| real problem is. Where to start? Ideas?

        If I remember Dennis Haynes post about smog (now in the files archive
on I think gerry.vangon.com). You have a rich running mixture since both
CO and HCs are elevated. A suggestion would be to check exhaust system
for leaks and then replace the O2 sensor assuming you find no leaks. The
O2 sensor will not produce as high a voltage for a given amount of unburnt
O2 in the exhaust. The lower voltage is interpretted as a lean mixture by the
ECU and thus the ECU orders a richer mixture (which is in fact too rich)...

        You might also have a dying temp sensor so check the its impedance per
the Bentley. Temp sensor either gains or loses resistance as it dies (cannot
remember which) but the overall effect is that the engine appears to be
running cold and the ECU dumps more fuel in an attempt to bring the engine
up to proper operating temperature. Someone might be able to tell you if
the O2 sensor signal overrides the temp sensor's enrichment because I do
not know...

        Also, with HCs and CO that high, your CAT may be burned out as well.

dave