I've got my Actron scanner connected and am watching the datastream.

When cold the O2 sensor is at 5 volts.

When warm and idling, it stays between 0.05 and 0.95 volts which I think is normal. (NO CODES).

But if fluctuates wildly in that range - going from 0.05 to 0.95 every second or two.

Is that normal???

Thinking this may be the cause of a fluctuating idle since it is adjusting the pulse width to the injectors; and they also fluctuate from 3.9 to 4.5 volts every couple seconds too.

IAC was replaced four times and TB cleaned.

Thanks.

 

A properly functioning O2 signal is going to swing from around 0v to around 1.0v (your .05v to .95v is normal). The faster you rev the engine the faster the swing will happen. It's better to watch the actual pattern on a lab scope than to look at the numbers because usually the numbers can't change as fast as the pattern on a lab scope so you're only getting a sample of what's really happening.

The O2 doesn't control the pulse with. The info from the sensor gets interpreted by the computer and along with other sensor readings then makes the needed adjustments to how the engine runs.

A.J.