The "smog pump", aka air injection pump, was necessary on the older carbureated cars because they had so much unburned hydrocarbons that they needed additional oxygen to burn all the hydrocarbons in the exhaust (especally when in the warm-up cycle). In fact the air pump was on many cars even before the catalytic converters. It had the dual purpose of adding more oxygen so the hot unburned gases could continue to burn in the exhaust system and it also helped to dilute the exhaust thereby "lowering" the tailpipe emissions. It isn't used on the Delorean because the exhaust is already very low in hydrocarbons so the introduction of additional oxygen isn't required to burn the "left over" hydrocarbons. Besides, putting the pump on only reduces the horsepower available to move the car, increases the cost and weight of the car and adds the complexity of another system. I don't know of any fuel injected car that has an air pump with a catalytic converter. The fact is the Delorean runs so clean that it doesn't even need an exhaust gas recirculation system. Of course it does need to be maintained to keep it running well. One fouled spark plug or dirty fuel injector can mess the whole thing up. A catalytic converter will glow red only because it is burning too much unburned fuel. Think about it, what can cause it to get hotter than the rest of the exhaust system, only if it is burning something inside. A too lean condition can't do that. A glowing red converter is a sign that unburned fuel is getting to it from the motor usually because a cylinder is misfiring but also if the mixture screw is set too rich. A cylinder can misfire for many reasons including; a bad/fouled spark plug, a bad ignition wire, a burnt valve, broken ring, blown head gasket, valves way out of adjustment, leaking, dirty fuel injector to name a few. David Teitelbaum vin 10757 --- In dmcnews@xxxxxxxxxxxxxxx, "content22207" <brobertson@xxxx> wrote: > Re: side by side Messages #39435 and #39436: > > The great "catalytic converter stops up because mixture is too rich" > vs "catalytic converter stops up because mixture is too lean" debate. > Fuel mixture may have nothing to do with it: > To address comments privately to the moderating team, please address: moderators@xxxxxxxxxxx For more info on the list, tech articles, cars for sale see www.dmcnews.com To search the archives or view files, log in at http://groups.yahoo.com/group/dmcnews Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/dmcnews/ <*> To unsubscribe from this group, send an email to: dmcnews-unsubscribe@xxxxxxxxxxxxxxx <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/