Post Catalyst Diagnostics In Rich And Lean Fuel Conditions

While it's true that an oxygen sensor can't directly detect raw fuel, it plays a crucial role in diagnosing fuel-related issues within your vehicle.
Today, John shows us how graphing the data from the post-catalyst oxygen sensor can provide valuable insights into your engine's performance. By analyzing the sensor's readings, we can distinguish between rich and lean fuel conditions, a critical step in pinpointing the root cause of various engine problems.
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[@ysitrim88]

Awesome video i figured that a ignition problem would cause lower voltage reading.

[@electron-john]

Glad it helped

[@stephenferraro]

So much useful info contained in such a simple and small sensor. Great video!

[@electron-john]

thank you

[@abdul-kabiralegbe5660]

So the difference between the ignition and spark misfires here is that for ignition misfire the O2 signal goes lean because of the unburned air from the bad cylinder while for an injector misfire the O2 signal goes rich because the catalytic converter absorbs the Oxygen from the bad cylinder?

[@mandytuning]

Looking some scanner danner videos about this topic is total the opposite spark misfire gies rich and disconnected inj goes lean. I tested on my acura it worked like that

[@abdul-kabiralegbe5660]

@@mandytuning Thanks!

[@autotech1100]

The voltage went down first when high rpm returned to idle. When the coil was unplugged the voltage went higher?

[@ysitrim88]

No, the voltage went lower because lack of spark.
If it was fuel-related the voltage would have gone higher.

[@abdul-kabiralegbe5660]

It seems to me he didn't rev the engine AFTER disconnecting the coil contrary to what he said earlier. The engine started sputtering after the coil was disconnected after which the signal went rich quickly.

[@dimisrambodimisrambo7285]

this is wrong when we have no sparks the rear O2 sensor goes high not low AFTER the mixture does not ignite and is rich when we have a lack of fuel then it goes low in the lean mixture

[@kd8icq]

The test shows otherwise…. 😂😂

[@dimisrambodimisrambo7285]

@@kd8icq NO IT DOESN'T SHOW THE OPPOSITE WATCH CAREFULLY WHEN THE COIL IS DISCONNECTED THE O2 SENSOR INITIALLY GOES RICH AND THEN GOES LEAN THERE THE COIL IS CONNECTED AGAIN

[@ThunderbirdRocket]

Thanks mate . Very helpful ! Data / evidence based lesson . Have a great day !! 👊🏼 🔥 💻 📈

[@electron-john]

thanks