Should an oxygen sensor ever read 0 mV if it is heated up, even if the exhaust is super lean? I've been getting readings of 0 mV with the occasional 4 mV, even though the engine seems to be running okay. Looking at O2 sensor info on the net, it looks like the bottom should be more like 100 mV as long as the sensor is heated up.

I'm wondering if my sensor is bad. It doesn't always read 0 mV, but it does when the car is at open loop idle, and I can't seem to give it enough fuel to bring it up. Possibly a bad heater? I've got a 3-wire Bosch.

 

Throw the bosch away and go buy a delco.

Bosch and 02 should not be used in the same sentence.

Replace it with the equivelant delco sensor :-)

Yes , super lean will indeed drive the 02 mv down to near zero.

In highway mode at 16-1 afr mine drops into the 2 digit range and low low 3 diogit area

later
Jeremy

 

Doc's thinking he's heard that before,

Truer words, yada yada...

 

I hate to say it, but didn't you just use Bosch and O2 in the same sentence?

Yeah, I ordered a Delco, just waiting for it to show up....

 

anybody have experience with Denso? somewhere i heard it was a very good unit? any specific production car use denso?

 

Just to update, I got my Delco AFS-74 installed and it did not solve my problem. It does seem to have a more subtle response than the Bosch, like it spends less time pegged one way or the other in closed loop, but it still eventually dropped to 0 mV on me at startup.

 

My friend has the same problem with his new engine..... His car switches between open/closed loop when he drives it no Error codes.......after a while his oxygen sensor hits 4mV and the BLM goes sky high.......

/N.

 

Man, let me know if he solves it. Does he have an EGR? I do not, so I'm wondering if possibly the ECM thinks it's turning on EGR and is turning down the fuel to compensate. I have the EGR-on VSS set to 255, but maybe that's not doing what I think.

Last night I finally cranked the BPW up to 175 and got the BLM to say 128 at idle. The idle was smooth, no gas pouring out the tailpipe. I'm not sure what it mean.

 

It was a bad *.bin? we started from scratch again and it worked... The only changes in the bad bin was inj.const and cyl.volume and some other basics but somehow it got bad....

/N.

 

Sounds like:

A: It is wayyyyyy lean

B: big ole phat exhaust leak :-)

If everything else is right mechanically and using closest bin to your setup available

later
Jeremy