I am using the Torque app to monitor sensors within my 06 Prius and noticed that the A/F ratio fluctuates between 12-18. Should I be concerned or is it somewhat normal? Posted via the PriusChat mobile app.
Hard to tell. Is there some reason why you're looking at these? Normally Prius is pretty good at giving you fault light and codes if something is wrong. Instead of looking at that you should watch fuel trims if you think there's something slightly wrong related to air fuel mixture. Short and long term fuel trims compare the engine to "perfect" engine. And because of that can tell much easier if there's something wrong. Maybe something like plus or minus 10% is still normal. If you would think that air fuel ratio sensor, oxygen sensor, or catalytic converter was bad you would check the signals of the air fuel ratio sensor, and oxygen sensor. But if you don't have fault codes and lights there shouldn't be much reason to do this.
Normal steady-speed operation should show 14.7:1 There are times when the engine needs to run rich and other times when it is safe to run lean, which is why you see variation on your display. The range you see is pretty normal, but not really that informative. I agree with @valde3 the fuel trims are a much finer-gauge instrument for tracking fuel consumption vs. performance.
my numbers are in the same range ..i have several months of data on my 2007 here: https://treecricket.com/priscope per @valde3 and @Leadfoot J. McCoalroller i have added display of long term fuel trim as well (guess im not setup to record short term?). mines sitting around -2 or -5 most of the time.
