[20v] Lowering Emissions 90Q 20V

[John Larson]

Another point needs to be raised.  When emissions levels are critical, as in
a test, you should always use the LOWEST octane fuel you can get.  Odds are
that additive you used wouldn't have been necessary if you'd done that.
High octane and "clean" have nothing to do with each other.  Higher octane
fuel is less volatile than its lower octane brothers, and doesn't burn as
easily.  That's why they use it in high compression engines, to prevent
predetonation.  I do this to aid cars in passing CA smog tests all the time,
and have been doing so for 30 years.  Dan's right, pushing it hard on
surface streets, using low gears and getting the engine good and hot is the
best way to get that cat working.  John