Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.1 6/24/83; site unccvax.UUCP Path: utzoo!watmath!clyde!burl!ulysses!mhuxr!mhuxj!houxm!whuxlm!akgua!mcnc!unccvax!dsi From: dsi@unccvax.UUCP (Dataspan Inc) Newsgroups: net.physics Subject: White exhaust and cold mornings Message-ID: <118@unccvax.UUCP> Date: Tue, 8-Jan-85 23:03:52 EST Article-I.D.: unccvax.118 Posted: Tue Jan 8 23:03:52 1985 Date-Received: Fri, 11-Jan-85 23:43:30 EST Organization: UNC-Charlotte Lines: 22 (If you have seen this before pipe it down to /dev/null) The condensation from the exhaust system is virtually nil in causing exhaust steam. Very rich starting mixtures, combined with those extra-stinky T.W.C. fast-lightoff catalysts, create the steam. Air injection ahead of the TWC provides enough oxygen to oxidize the HC-rich stream into H20 and CO2 raising the converter temperature until the COC can take over. At this point, either the choke has come off or the catalytic converter temperature is so high that the dew point is below the exhaust stream temperature. (Actually, the COC does not take over in sanitizing the exhaust stream. Initial oxidation, however, is provided by the TWC). This effect seems to be most noticable with certain brands of cars that have the HUGE underfloor converters (presumably to get away with richer choking mixtures ?). I have noticed the effect in my EFI Escort. Why should an EFI car require cold enrichment ? dya