Hey all, just wanted to post an FYI for anybody going through the same hell that I endured for the last two months:

After replacing my 3.4L supercharger (with 200k miles on it) with a new 2nd-gen model and URD 7th injector kit with 2.2" pulley, the truck was running like crap.

Basically, the truck's acceleration was hesitant and rough. It would do fine until the supercharger started really kicking in (around 2600 to 3000 rpm), then would cut out and barely rev. But the biggest problem was a lean backfire that occurred when downshifting.

While cruising along at ~40 mph, if I stepped on it, and the tranny downshifted, it would cough and sputter and backfire. I THREW 3 ALTERNATOR BELTS THIS WAY!!! I ended up spending a small fortune troubleshooting the problem with a local tuning shop (btw, Gadget at URD did his best, too).

Long story short (actually, a VERY long story), I chased down the part number for the IAC (Idle Air Control) check valve -- that wasn't provided with my s/c kit -- and installed it out of sheer desperation.

$5.99 (plus tax) and 3 minutes later, the problem was cured. AMAZING. Truck runs like a champ. I wish I would've known about it when I first installed the kit!!!

For anyone encountering this issue with a 3.4L TRD supercharger, here's the new Toyota part number for a 1-way IAC check valve (since the TRD part number won't work anymore and the idiots at dealerships won't help you find it):

PTR26-35042

Install it. The directions say you don't need to for certain models, but install it anyway (when installed correctly, valve should block air from entering the throttle body).

Anyway, I really hope this helps someone down the line!!! <img src="/forums/images/graemlins/scared.gif" alt="" />