2000 Corvette drive-ability/power loss?; data log available

[AALynch]

Hey guys, I'm hoping someone may have some advice for us - anything would be helpful!

My dad has a 2000 Corvette, bone stock aside from a K&N filter, that's he's owned since brand new. It's got right around 90,000 miles on it and he has never had a single issue with the car until this.

Last summer(I believe), the car just started feeling down on power. At approximately 2,500 RPM, in any gear while under more than probably 30% throttle, the car just kind of falls on it's face and feels like it's got about 200 horsepower. At that time, we replaced the plugs, plug wires, FPR/filter, and it didn't solve it. He took it to a Chevrolet dealer near him, and they kept the car for a few days, only to replace his plug wires and tell him it was fixed.....it's not.

To be honest, I'm not good with this tuning software and don't have too much of an idea what I'm looking at - I purchased the software 100% to remove VATS and random DTC codes for a motor swap I did. The car IS throwing DTC's now for both "sensor 2"s on both bank 1 and bank 2 - these should be the post-cat 02 sensors, correct? And if so, this should not affect the power of the vehicle, correct? If these should be addressed prior to anything else being looked at, he's planning on doing that soon anyways, but they haven't shown up before....however, the DTC scan did show:

[] P0137 - O2 Circuit Low Voltage (Bank 1, Sensor 2) (Old) (Immature)
[] P0157 - O2 Circuit Low Voltage (Bank 2, Sensor 2) (Old) (Immature)

....what does "Old" and "Immature" mean?

My dad told me tonight that this car has NEVER had a check engine light until tonight, when I think resetting may have triggered the light. I'm not sure if this offers ANY insight to you guys, but here's a screenshot of the data log, in 4th gear at WOT...looking at this, I know there's not an issue with the throttle body as it's registering 100% throttle, but the 02 readings (52 and 35 mV?! Very lean??) and the LTFT(long-term fuel trims; is this the engine trying to adjust from a factory fuel table and adding 19.5% more fuel than expected?) seem very off...the way I understand this, the LTFT adjustments are a result of the wonky 02 sensor readings....essentially, the car is trying to dump fuel in to correct the bad AFR?:



I'm hoping someone knowledgeable with VCM Suite could check out this log - we've got 3 or 4 WOT pulls recorded so I'm hoping someone here might have some advice on where to go from here? If anyone has the time/knowledge to help us both out, I would greatly appreciate it - after the last trip to the dealer and the bill that came with it for nothing, I'm not sure he wants to go back to another.

Thanks guys!
Adam

[mecanicman]

Start with checking your fuel pressure, at idle as well as under load. If that checks out pull a precat o2 sensor and put a pressure gauge in.

[AALynch]

Is there a good way to monitor fuel pressure while driving? We've checked it at the rail with a gauge off the front of the rail, pulling out the shraeder valve, but I wouldn't know how to watch that while driving?

Thanks again guys....I'm not sure how much/what could be pulled from that log file I attached, but that's why I put it up

[mecanicman]

Buy or borrow a gauge that you can run out the back of the hood and put on windshield.

[2xLS1]

Your O2s are at 35 and 52mv at WOT where you have the cursor in that log. It is stupid lean. It's possible the K&N has really gunked up the MAF sensor, but it's probably the fuel pump. A spray can of MAF cleaner is cheaper than a fuel pump so I would try that first. Check the PCV valve hose for rot and a leak between the valve and the intake manifold too. Passenger side right behind the throttle body.

[RonSSnova]

Ya, it's lean. And it's not flowing any air at all. The MAF reading should be much higher at WOT.
Fuel pump is a good bet. If it has no fuel, it can't flow any air. It goes lean when you barely lean on it.

Nice job by the dealer.......jesus.

Ron

[SultanHassanMasTuning]

very lean...

[Russ K]

Looks like a bad Maf, just unplug it and do another WOT scan. If the O2's hit >800 mv, then replace the Maf, very common problem.

Russ Kemp

[gagliano7]

Make sure the cats aren't clogged.

[Russ K]

Make sure the cats aren't clogged.

Restricted cats/exhaust causes the O2's/wideband to read rich.

Russ Kemp