[DML] Re: PRV Catalytic Converters -- Volvo vs DeLorean

["content22207" <brobertson@xxxxxxxxxxxx>]

Smog pumps are standard issue on Volvo F series PRV's. Look closely at
the full size front view pic of my B27F and you'll see it in the lower
left corner. Of course they rob power -- that's one reason I remove
them. They also depend on a Rube Goldberg water temp/vacuum system,
which doesn't age well, to only inject air under certain engine
conditions.

Other than the DeLorean, I've never seen a turn of the decade
catalytic converter equipped vehicle without a smog pump from the
factory. I wonder if JZD simply omitted so he'd have some place to run
his exhaust tubing. If my DC area mechanic is correct, the smog pump
is indeed there for the converter's benefit, which would explain why
simply removing it eventually causes problems. The air passages are
tiny. Without additional burn time, they could easily clog up with
soot. I have noticed that the tailpipes on my de-emissioned vehicles
accumulate a lot of soot even though the spark plugs indicate a good
burn inside the engine.

Re-read Delorean3469's message: he stated both manifolds were glowing,
not the converter itself.

Bill Robertson
#5939

>--- In dmcnews@xxxxxxxxxxxxxxx, "David Teitelbaum" <jtrealty@xxxx> wrote:
> 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:
> >




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