Ok guys, I really wanted to update this for anyone else that ever bolts this supercharger up. It took quite a while and a lot of sleuthing and a little luck to root cause this issue. It drove me crazy because other people reporting similar issues NEVER reported back what they did to fix it. I didn't want to leave anyone hanging that might find this on the interwebs and need help. If you find this, I hope it helps you. This is my public service announcement of sorts.
This was my original symptom-
Unfortunately, it is running very poor at WOT right now. The key symptom is the truck is boosting higher than it was and the truck is stumbling at WOT. After research, the real only way this can happen if everything else is ok is the cats are in bad shape, i.e. partially clogged. This increases back pressure which increases the boost level of the supercharger. Upon reading, a lot of cats aren't designed for the higher temps that forced induction brings. I had some Magnaflow cats on there. They must still be breathing some, as they got me past smog, but they must be partially clogged to be blocking flow at higher rates.
Ok, so the cats tested fine. Good. That would have been expensive. I also pulled my NGK TR6 copper plugs (one range colder than stock) and checked they were gapped to .030 as specified by my tuner. the plugs actually didn't look bad; no deposits and a nice tan finish on the ground strap. I was starting to run out of ideas and considered just pulling the supercharger and going back to the stock intake/injectors.
then, I finally was able to equate the issue to my WB02 AFRs and the lightbulb came on. I'm gonna say that if you want to get a supercharger that a WB02 sensor and gauge is pretty much mandatory. You just can't trust that everything is working perfectly blindly. As I was driving the truck on Saturday on the freeway, I noticed that the WOT stumbling came with a lean spike in the AFRs (when the supercharger is pumping 4-6psi into the engine); the lean spike ONLY happened at part throttle or WOT; it held stoich fine at cruising/idle. After a few times seeing the WB02 AFRs spike (~16:1) at part throttle or WOT, I finally hypothesized what was happening: the truck was misfiring only at part thottle/WOT! Why did I suspect a misfire? Well, I surmises all of the forced air dumping into one cylinder didn't get combusted, and just passes through the exhaust and the WB02 sensor sees the AFR spike up on account of a higher air reading.
Ok, I started reading on the Internet and there was data suggesting that a misfire causes a lean AFR spike! Now, I knew the plugs color was good and there was no sign of detonation, so it couldn't be a fuel injector. Then, after more research, I came to my root cause: the forced air jamming into the cylinders coming from the supercharger was blowing the spark out, literally! Like how a birthday boy blows out his candle. Instead of igniting the air/fuel mixture, the spark blows out and no combustion. Lot of data out there to support this.
So, I went and got new TR6 plugs, and I very carefully gapped them to .028 instead of the .030 from before; I used a feeler gauge instead of the hooks of the spark plug gap tool. I noted that the old plugs I took out ranged from .030 to .032. Well, long story short the .028 gap did it! No more spark blow out, no misfire, no part throttle/WOT lean and the truck is a LOT faster.
