Vanagon F4-1915cc 1.9L (Water Cooled) (1983)
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Catalytic Converter: Technical Service Bulletins
Exhaust - Sulfur Odor Noticed At the Pipe
GROUP: 26
NUMBER: 94-01
DATE: February 11, 1994
SUBJECT:
Sulfur odor at exhaust pipe
MODEL(s):
All All m.y.
CONDITION
During certain operating conditions a sulfur odor (rotten eggs) may be noticed at the tailpipe.
The odor is present because of:
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Sulfur content of the gasoline
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A characteristic of catalytic converters - including Three Way Catalytic Converters (TWC) to store sulfur compounds (SO3) and release them
during richest engine running conditions, i.e. idle or heavy acceleration.
During relatively lean engine running conditions sulfur in gasoline is converted in the combustion process into sulfur trioxide (SO3).
During relatively rich engine running conditions (idling or heavy acceleration) sulfur trioxide is converted into hydrogen sulfide (H2S) within the
catalytic converter or TWO. Hydrogen sulfide has the characteristic "rotten egg" odor.
SERVICE
Recommend that the customer try a different brand of gasoline. Another brand may have less sulfur content.
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Generally, premium grade fuels have less sulfur content than regular unleaded fuels.
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The sulfur content of gasoline can vary from one geographic area to another.
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It may take several tanks of a different brand of fuel before a change might be detected.
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The "rotten egg" odor will tend to lessen as the catalytic converter or TWO ages. H2S odor is usually less noticeable on vehicles with more than
6000 miles.
