My car used to run around 11.2 afr at WOT. Recently is started going up to 11.8-12.0 so I've been hesitant to floor it even. I just did some logs and verified airflow readings and checked my fuel map for target afr and it should still be targeting 11.1-11.2. There is a very small spot of soot where the o2 housing bolts to the turbo but I don't know if it's enough to cause and issue even. The car isn't seeing knock so I don't know if it's a sensor issue or something else. The wideband is an AEM UEGO and there's about 30000 miles on the sensor. Ideas / things I can try? At idle and cruise the wideband still shows 14.7-15.0 as always.

( this is a bolt on car running 93 octane )

 

Well the wide band is after the o2 housing so it is possible. You can try re calibrating the o2 sensor then try it again. That's a free and easy way to test the sensor. A quick search will show you know to do that.

 

I didn't think there was a way to recalibrate the AEM UEGO widebands? I would assume you have to have a pretty serious exhaust leak to effect the numbers like that correct? It literally just looks like a black line maybe 1/4 long along the side of the O2 housing gasket in one area. I ordered a new sensor for the wideband, we will see if I get different readings with that.

 

I replaced the O2 housing gasket and the wideband sensor. Wideband is now more responsive but above 5000-5500 in higher gears it starts to lean out to around 11.5-11.7 still. Still no knock picked up, 93 octane and 25-26 psi. Any other ideas at this point?

 

how old is the pump?

 

Did the ethenal level in the gas you buy change for winter time in your area? Are you fuel trims off too? Just something else to consider...