Hi,

Could someone tell me what live data reading I should be getting under idle and driving conditions for my 05 blazer?

I understand there is 4 o2 sensor's?

If the voltage drops is that a concern?

 

There are 3 sensors on your 2005: One on each side of the engine in the exhaust pipe, close to the exhaust manifold. These sensors are used for fuel control. Once the sensors warm up, they create voltage ranging from .1 volts, (lean fuel mixture) to .9 volts, (rich fuel mixture). The upstream sensors, (B1S1 and B2S1) voltage should constantly be changing. The target voltage is .45 volts, which is a perfect 14.7:1 air fuel mixture. The PCM adjusts the injector pulse width, (amount of time the injectors are open) to bring voltage back to the target. The faster the sensor can react to mixture changes, the faster the PCM can adjust the injectors, and the better fuel mileage and performance you can expect. Oxygen sensor reaction time slows down over miles. Referred to as a "lazy" sensor. Usually around 100K miles it has slowed enough to substantially affect performance and fuel mileage, that's why they recommend replacing them at 100K miles

The third sensor, (B1S3) is at the catalytic converter outlet. This sensor monitors the performance of the converter, that's it. It does not affect engine performance or fuel mileage. The downstream sensor should indicate a constant low voltage, usually around .3 volts. If it's higher, it could indicate an overly rich fuel mixture, or a failing converter.

 

Thank you very much for the detailed answer and teaching me about my truck.