I am going to be hooking my car up to my friends scanner to take a look at my o2 readings.

But what should i be looking at?
What are some basics to checking the o2 readings


THANKS!

 

Look for frequent "crosscounts". This means constant switching above and below 450mv("rich to lean" and vice versa). That will indicate a good, active O2 sensor.

Next, take the car out for a WOT run. Look for around 780mv to indicate that the A/F ratio is decent. Remember, the OEM O2 sensor is only accurate at 14.7:1, which is way too lean at WOT. So the 780mv at WOT will just indicate that you are in the ballpark, and is no substitute for a wideband O2 scan.

 

off the top of my head the lower the # the less raw fuel. If the #s are high then you are more rich.

At WOT the numbers should be around 900.

If it bounces around during idle then it needs to be smoothed out. If it jumps 200-1100 then it needs to be looked at.

Sorry so vague. I have been in the Army training. I was messing with this before i went in about 5 monthes ago so.....

 

As Josh stated above, healthy O2 sensors should be very active (bouncing above and below 450 mV) when at operating temperature. Slow moving sensors have been coated over time and are not sensitive to changes in O2.

I would not tune my car based on WOT stock O2 sensor readings! They are not accurate and a lean running engine can take out your pistons! Spend a couple of bucks and go to a dyno with a wideband O2 sensor setup.

 

For scanner use info, including O2 readings, check out this document.

Incorrect. As noted, should be switching between lean (0xx mV) and rich (9xx mV) at idle, up to 10 times per second. This is completely normal.... in fact, as noted in the other two posts with correct info, if it doesn't jump around like this at idle, you probably have a problem.