strange leanness

[mr.prick]

i was minding my own business the other day (in closed loop maf)
when out of the blue under hard throttle(40%+)
i was hitting lean (16afr+) :eek: for no reason.
i went into open loop with PE enabled to see if maybe i just needed more fuel
in my VE table but it was doing it in OLSD as well.
i have been hitting 85% duty cycle on my injectors as of lately ,
usually they are 75% and i have been seeing a high fuel pressure anomaly.
but for the longest time no matter how much fuel i wanted
i could get it by adding at will.
it seems to only be at the higher kPa areas only and it fluctuates,
it will hit my commanded then hit lean very rapidly.
i saw zero KR in the lean spots.
i am wondering if it is possible to be at the edge of duty cycle for so long
and be ok , then all then sudden be over the
limit of the injectors ability, or could this be a sign of wide band malfunction?

[5.7ute]

I have had a wideband malfunction do exactly what you are describing. In my case it was from moisture hitting the hot sensor. It would read fine while at a light cruise but whenever a decent amount of throttle was applied it would read lean. After a few days under throttle it started going out of range lean.
To be on the safe side I would check my fuel pressure as a failing pump can cause the same thing.

[mr.prick]

hmmmmm
my pressure is actually abnormally high for what i`ve been told (70psi)
but it has been high for a while with out this phenomena.
i am going to clean my WB and see what happens.
i don`t see how any moisture would be hitting my sensor.
i am running at full operating temperature when this occurs.

[5.7ute]

The moisture that destroyed my wideband sensor was from a mechanical failure. While this may not be the case in your car it does show what weird readings you can get with a faulty sensor.
As for fuel pressure I log it in every car I do now. I had a ute with a pump issue that only lost pressure under wot conditions. Being able to see the fuel pressure dropping prevented melting down his engine.

[mr.prick]

02 sensor was the culprit.