First off based on your Toyota's CO results we can tell the engine is
running rich. It may be running rich due to the ignition timing being off;
so this is the first fault that needs to be repaired. Once the ignition
timing is fixed (whether due to the timing belt or else) you should re-test
your Toyota and get new emissions readings. From there, if the CO (carbon
monoxide) is still high you'll need to look into the fuel feedback system to
ensure the oxygen sensors and other emissions sensors are relaying correct
engine data to the emissions computer, allowing the emissions computer to
determine the proper amount of fuel to deliver to the combustion chambers.
By the way... High HC (hydrocarbon) is almost always due to ignition related
problems, unless it's due to a rich misfire. So again, have the timing
problem fixed first before doing anything else.
The ram intake should not effect CO as (I'm assuming) this is an aftermarket
OEM intake part which should not alter fuel delivery. As far as the correct
fuel to use; we only recommend using the fuel type/octane required by your
specific Toyota model (Corolla). Any other octane of fuel will alter the
air/fuel mixture. Finally, after all other emissions components are
inspected and no faults found, or faults found and repaired, you can suspect
the CAT of being defective. A CAT intrusive test is best to determine if the
Catalytic Converter on your Toyota is defective. If so, go ahead and replace
the CAT. The intrusive test is a simple test using a smog machine or gas
analyzer, taking exhaust sample from before the CAT and after the CAT and
comparing the results. The Catalytic Converter should absolutely be the last
component you replace.
