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-   -   Front 02 sensor dead, i think (https://www.evolutionm.net/forums/ecu-flash/343961-front-02-sensor-dead-i-think.html)

dryad001 May 7, 2008 08:18 AM

Front 02 sensor dead, i think
 
Right now I am getting horrible gas milage, about 150 to a tank if Im lucky. The cruise AFRs are around 11.8-12.1 The sensor has 50k on it with a ton of race gas and methanol sprayed onto it over the years. What Im wondering is what should the front sensor read during cruise? I get about .02V during cruise. Ill have a log up here to show in a few moments

dryad001 May 7, 2008 08:23 AM

http://i18.photobucket.com/albums/b1...1/untitled.jpg

Jack_of_Trades May 7, 2008 09:23 PM

wow, you're getting a ton of knock continuously! Those AFR's definitely suggest a bad Front O2 sensor. Have you logged the frnt O2 sensor while in closed loop? It should cycle back and forth from .1 to .9 volts roughly. The resolution of that snapshot isn't good enough for the front O2 sensor readings but it sure looks F'd to me.

Nood1es May 7, 2008 11:20 PM

wait so a normal working front o2 at closed should range from .1-.9 correct?

RazorLab May 8, 2008 12:51 AM

Cruise AFR's should bounce around Stoic (14.7:1) and your narrowband 02 voltage should cycle from around .79 to .05 under idle and cruise.

I would say your front 02 is dead.

tephra May 8, 2008 05:11 AM

you should get a CEL for it thou...

JoeBee May 8, 2008 06:09 AM


Originally Posted by tephra (Post 5638406)
you should get a CEL for it thou...

Jea, when it doesn't occillate and don't throw a CEL it is may stuck in an open loop mode. Log also all logable sensors and check them for plausibility.

dryad001 May 8, 2008 09:35 AM


Originally Posted by Jack_of_Trades (Post 5637705)
wow, you're getting a ton of knock continuously! Those AFR's definitely suggest a bad Front O2 sensor. Have you logged the frnt O2 sensor while in closed loop? It should cycle back and forth from .1 to .9 volts roughly. The resolution of that snapshot isn't good enough for the front O2 sensor readings but it sure looks F'd to me.

That was knock voltage, not counts. As far as I know it is now officially dead, in Evoscan this morning it wouldn't even read 0.001. During closed loop it will range from .10 to .41 thats the highest Ive seen it read

Tephra- Ive had a PO171 for about a year. It would come and go every week or so. I think this winter did it in. The new one is showing up today whenever UPS decides to drop it off, Ill throw up an before/after log as well when its in.


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