Strange Readings

I’ve probably made a mistake but I am not sure what. I have a Spartan 3 and I am using the CAN bus value. I take the 16-bit, big-endian raw value and multiply by 0.0147 to get AFR.

Engine is fully warmed up. Sensor temp is at the required value and holding steady.

I rev the engine to 2,000 RPM and 3,000 RPM and then AFR goes up. At no point does it drop below the idle AFR value of 12.8.

Shouldn’t it go down?

Sensor is installed at 90 degrees close to the engine in the same location that has worked for others with the same make/model of car. No cats.

Double-checking what I am doing on my laptop:

If the first two bytes of the CAN message are 03 E8 then my CAN software reports an AFR of 14.7
If the first two bytes are 03 FF then I get an AFR of 15.038.

So that confirms an increasing Lambda results in an increasing AFR.


I figured it out. I figured it out.

Just curious what was the problem ?

Is 0.0147 the right multiplier from lambda to aft on gasoline ?

Is this forum still active ?

14.7 is the AFR multiplier for Gasoline.