I would suspect the fuel pump or even the fuel filter. I knew you were running into a lean issue as soon as you mentioned that the WB02 was "getting too hot". This should never happen. You might want to stick a borescope down in the cylinders and check the condition of the pistons...running that lean can melt shit with a quickness.

Piston damage?
 

That would royally suck to lose a motor from a plugged fuel filter or aging fuel pump, but that is a clear possibility. I'll see if my Harbor Freight scope will fit through the plug holes, but i think it is too big. Good idea. Thanks.

I say fuel pump. Also, its unlikely but your fuel pump voltage or power supply could be taking a hit at that rpm for some reason.

Problem SOLVED!!
 

Looks like we nailed it! :winner: Thanks guys. This is why I love this forum.

Tonight, I installed my new Walbro 255 Lph fuel pump and took it for another test drive. Before the pump, my fuel pressure at idle was 61 psi and by 5,500 at WOT it dropped down to 38 PSI. It was even lower before changing the fuel filter, but I did not record it. More importantly, at WOT above 5,500, the AFR jumped to 20:1 (extremely lean).

After installing the new pump, the idle pressure is 68 PSI and under max load at WOT, it never drops below 60 PSI. The AFR is now at the opposite extreme. At WOT at 5,500, it is way rich at 10.8:1. This means the lean issue is absolutely fixed by the fuel pump. Now it is running rich because it was originally tuned by BEGi with the OEM fuel pump with lower pressure. It was dark outside, so I could not see if it was putting out black smoke from running that rich. I'm guessing it is.

I have another question.

Before the fuel pump failed, the AFR was in the 12-13 range at max WOT max load. What are the side effects of running this rich (10:1) at WOT? Is is just low fuel efficiency, black smoke, slightly reduced power, and more likely to foul plugs sooner?

Thanks again guys for the help. Looks like my TWS weekend is going to happen. It is not nearly as much fun to instruct when you don't have your car to go play. :D

Well you can also clog your cat with soot

wash the oil off your cylinder walls - not sure this would happen at 10:1 but maybe your wideband bottoms out at 10:1?

why not just do some logs and adjust your map bit by bit?

Yeah...WAY too rich. Running too rich also cools the exhaust gasses and makes a difference in spool. Oddly enough, running that rich will cause unburned fuel to build up in the catalytic converter which will then get too hot and glow red...nasty things can happen under the car when that happens. Other effects are a severe loss of power and contamination of your engine oil.

What psi are you running now? I see 10 in your sig and AFRs in the 13's might be a hint on the lean side as well.

Must re-tune after new fuel pump - WAY RICH
 

Thanks, faeflora and Doppelganger. I appreciate the input. Yes, I'm running 10 PSI and yes, I need to bite the bullet and re-tune. I'm attempting to do this now for the first time myself. I will attempt to take some logs with my LC-1 tomorrow and figure out how to program the XEDE system. I called Stephanie at BEGi today and she was EXTREMELY helpful and gave me plenty to read. It does not sound too difficult, but I need to get this done in one day because I have very limited time before my TWS event this weekend.