Low O2 Volts

[PIreland]

I took that car out today with a new chip and alkycontrol chip and PowerLogger. Most things are fine except that my O2 volts are exremely erratic and are VERY low at WOT. PowerLogger recorded as low as .071 volts at 16.6 psi boost, knock retard was .4 degrees.

While at WOT, the O2 seems to be fairly smooth but at 60 MPH and at idle and speeds in between they jump all over the place. The volts jump from .094 to .693 in less than a 1/2 second. So, as you can see, things are very erratic.

I'll check the grounds. Any other ideas?

I also posted this on TurboBuick, received suggestion to check Fuel Pressure (haven't done that yet).

Thanks

[Electrajim]

What the voltage is doing sounds normal.
Yeah, start with checking your fuel pressure.
I'm guessing it's a little low.

ElectraJim

[Keller]

Originally Posted by Electrajim

What the voltage is doing sounds normal.

Yes...but NOT at WOT!

How fresh/new is the sensor? Has any lead been run though it?

What version of the software are you running?

What are your crosscounts at idle once warmed up?

[PIreland]

The O2 sensor is a couple of years old with, maybe, 5000 miles on it. No leaded gasoline ever used.


I'm using PLC Version 1.2.3

Cross Counts at Idle, in gear, warmed up is 97

Here is my theory and I need to retest to see... I had an alcohol leak (pretty big one, the AN fitting wasn't tight ) where the line attaches to the UP pipe. My theory is that when I was boosting, the alcohol was flowing and spraying all over the place and it was getting on the outside of the O2 sensor and ruining its reference to ambient. Sound plausible?

Thanks

[Keller]

Originally Posted by PIreland

Cross Counts at Idle, in gear, warmed up is 97

The cross counts will vary frame-to-frame. Are you getting ~97 per frame jump? That would be a lot, and very unusual.

The alcohol on the outside of the sensor may have damaged it. Also, you may have an air leak somewhere.

[PIreland]

The 97 cts were steady over a period of about 4 seconds.

I don't know if I broke the O2 sensor. I have to wait for some nicer weather to bring the car out on the road again. I'll probably get the car out this weekend.

As far as the change from frame to frame. The frames are about .050 seconds apart on the power logger and after a quick look, I don't see the counts changing by more that 2 cts from frame to frame.

Thanks again.

Patrick

[Keller]

At least on a standard (i.e. slow, with 1.4 seconds between frames) scan tool, the cross counts should count from 0-255 by large jumps and go around again. They should not stay constant, save for (a) when the car is not yet at closed loop and (b) at WOT. With DirectScan/PowerLogger, the jumps will be smaller due to a faster frame speed, but still most constantly stave for (a) and (b).

If you aren't getting this, your sensor may be damaged.

[kenmosher]

Well, not all ... some (like TurboLink) will actually display a DELTA cross count number (i.e. change in cross counts from frame to frame).

[PIreland]

I replaced the O2 sensor, now everything is fine.

Thanks for your help.

Regards,

Pat Ireland