The Lambda calculator is great for determining if fuel delivery is the source of a running problem. The great thing about lambda is that it is accurate at the tailpipe, even with a working converter. Sometimes exhaust gas numbers can be deceiving. Use the calculator to know for certain if a mixture is rich or lean.
- Make sure there are no exhaust leaks. Excess oxygen in the exhaust stream will skew the results.
- Make sure the secondary air pump (if equipped) is not running.
- Run the engine at idle, and then again at 2500 RPM no-load. Record all gas readings and plug them into the calculator.
Lambda 1.0 is considered perfect 14.7 to 1 air fuel ratio. For every 1% lean lambda increases by .01. For every 1% rich, lambda decreases by .01. Therefore, a lambda reading of 0.89 indicates an engine is running 11% rich. A lambda of 1.10 means that the engine is 10% too lean. Typically, you should expect to see 0.95 to 1.05 with most vehicles.