It comes from lead in the gas reaching the catalyst in the converter
producing a rotten egg smell. It ISNT from the cat going out, it isn't from
to much(or to little) gas, its from lead! I KNOW they don't sell leaded gas
anymore! But allot of companies still have a minimal lead content in their
gas. Running hard definatly doesn't help because it increases the amount of
lead on the catalyst before it can be burnt away. That is the main reason
the Euro-Trash sport compact junk driven by theses
wet-behind-the-ear-daddy-leaches crank by and leave rotten egg smell
behind...That is SO cool...
The factory converter in '87 far beyond SUCKED! If you must have one due
to legalities, replace it with a monolithic design(straight-through)
converter. You should still be legal and the poor choked-nearly-to-death
truck will breath MUCH better and be very thankful.
The smell is from the cat that is no longer up to the job. On an 87, this
may be because it is just worn out. On newer vehicles, it is often because
of an over-rich condition that the cat just can't keep up with.
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