dsi@unccvax.UUCP (Dataspan Inc) (01/09/85)
(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 ?
dyamat@amdahl.UUCP (Mike Taylor) (01/12/85)
> > (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 If that's true, why did it happen BEFORE catalytic converters existed? Secondly, in very cold weather ( in Canada, anyway ) exhaust steam continues at all times, even though the engine is at normal operating temperature. -- Mike Taylor ...!{ihnp4,hplabs,amd,sun}!amdahl!mat [ This may not reflect my opinion, let alone anyone else's. ]