Catalytic Converter

The Catalytic Converter has several groups of tables associated with it. These will need to be adjusted after removing the CatConv for off-road or racing purposes.

Catalyst Heating

Several tables are used to raise Idle Speed, increase Fuel, retard Timing, and even turn on VANOS, in an attempt to heat the CatConv as quickly as possible since cold start emissions are usually the most polluting.

This behavior can be disabled by setting all 4 of these tables to 0.

Catalyst Overheating Protection

To prevent the CatConv from overheating, the ECU can slowly enrich Fuel to cool it down.

This behavior can be disabled by setting the "COP - Fuel Enrichment - Nominal" table to 0.

Catalyst Efficiency

0-5V narrow-band O2 sensors are used to detect either a rich or lean condition. The ECU wants to see a perpetual and evenly timed fluctuation from rich to lean and back to know the AFR is hovering around 14.7 or a Lambda of 1. To gauge Catalyst Efficiency, the ECU wants to see a tighter/smaller fluctuation from the rear (Downstream) O2 sensors as compared to the front (Upstream) O2 sensors.

This can be disabled using "DTC 79,61 - Downstream O2 Sensor Heater" and unplugging the rear O2 sensors electrically. They can be left in the exhaust pipe or removed.

Some common DTCs have an "Alternate" method which need to be used in some cases, if the normal option doesn't work.