NB O2's & Lean WOT

[RevGTO]

I've been running the same Calc.VE tune for over two years and had my AFR's dialed in pretty closely. Several weeks ago I went to the track for the first time in a year and a half. My times were off about 6 tenths and 7 mph. Since then, I've been able to determine that when I go WOT, my NB O2's initially peg to 850-950mv and then crater to 75-150mv and hold there. AFR's are in the 16-18:1 range when the NB readings are low. I'm lucky I haven't blown my engine!

I unplugged my MAF and logged and got the same behavior. MAF has been cleaned, fuel filter replaced, injector cleaner run, I have no apparent misfire, no DTC's, and the NB's seem to perform normally at part throttle. IBPW, Maffreq, INJDC all are normal. I should mention that I do have my O2 sensor DTC's turned off because of the usual low voltage/switching codes that occur with LT's.

Any suggestions??

[joecar]

Post log files.

Also check physical aspects: fuel pressure, fuel filter, injectors, etc.

[RevGTO]

As I mentioned, I changed the fuel filter, haven't had the time to get a fuel pressure gauge hooked up and check it yet.

Here are a couple of log files:1419314194

[joecar]

I finally caught up with this thread...

your log files show that your NBO2's might be worn out and/or fouled;

you might have a fuel delivery problem (dirty injectors, insufficient fuel pressure, leaky FPR, dirty fuel filter).

[RevGTO]

I've been in CA and the car's in KS, but when I got back I got it on a dyno and that showed fuel pressure dropping off severely beginning at 4500rpm. Fuel pump/regulator is where the problem is centered ...

My NB's are probably pretty tired. They were used Corvette rears with 40k when I bought them. Worked great for awhile and then started throwing the usual codes that come with LT's (codes have been turned off for a long time now).