LAMBDA 1.0

Lambda 1.0. That's the number everything else is measured against. Your scan tool shows lambda. You see 0.97. You see 1.04. Most techs grow past it. That number is telling you exactly what the engine is doing with its air fuel ratio in real time. Lambda is a universal measurement of air fuel ratio and it doesn't change by fuel type. Doesn't change by engine size. It's the same number on every vehicle. Lambda 1.0 indicates stoichiometric air fuel ratio. Perfect combustion. The exact ratio for air to fuel where everything burns completely or almost 14 to 7:1 on gasoline engines. Lambda above 1.0 indicates that the vehicle is lean. More air, less fuel. The higher above 1.0 the leaner the combustion. Lambda below 1.0 indicates a rich. More fuel, less air. The further below 1.0 the richer the condition. Here's why it matters on your scan tool. A wide band air fuel ratio or wide range O2 sensor doesn't report in voltage in the way a traditional zirconia O2 sensor does. It reports a precise air fuel ratio and many scan tools display that as lambda. Lambda at 0.85 at idle with no load, that engine is running significantly rich. Lambda of 1.08 under light cruise. Now that's lean. And you need to find out why. One number, one universal scale. Works on any car you put it on. If you haven't been reading lambda, you need to start yesterday. I'll see you on the next one.