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Some (if not most) of you probably know this, but I discovered it today.
It may not apply to stock TBs, but it wouldn't hurt to check.
So, here's what you do, and later, why;
1) Take off whatever intake tube you have connected to your TB, so you can see your butterfly valve.
2) Then wedge something (I used a Golf Club handle) between your seat, and your gas pedal, so it's all the way down, like you were at Wide Open Throttle.
3) Adjust the throttle cable slack nuts, until your butterfly is exactly horizontal.

Here's why: After 16 years or so, you could get slack in the cable, and it wouldn't open the throttle all the way, and more importantly, if you're like me - always screwing around with stuff, it could go way off.
For instance: I figured this out, because I put a bored out DE TB onto my KLG4 IM, and wanted to be sure everything matched up. Sure enough; when I pushed thre pedal to the metal, the butterfly opened pretty far past the WOT point, essentially closing the throttle slightly, which would cause a loss in performance. Mine is an extreme case, since I have the [externally] normal DE TB, K8 (I think) Throttle cable cam, on my MX-3.
After you do this, you need to do the TPS calibration again (which should be checked every couple of years, anyway).

Sounds good, Jesse, except I'd get someone to stomp the pedal instead. I have even tried using a 3' adjustable C clamp, pushing it against my seat, but it still always has a bit of slack in it.

I was all alone
Mine couldn't be pushed any harder against the floor... maybe it's the angle. I jammed the other end into the lumbar bolster of the lower right side of the driver's seat. If you have someone with you, then, yeah, have them mash it.

How did you get it to open past the WOT point, isn't there a stopper? Or did you change that while in process of boring it out?

Good call. It's been so long since I've done anything with an unmolested TB that I forgot. I have 5 or 6 TBs and only one is unaltered. It is a ZE, and it does have a stopper, but it stops just barely before WOT. If I had it on my car, I'd shave the stopper down a tiny bit.
So, for unaltered TBs, this would just help you know if it is getting to the stopper, for which you'd not have to take your intake off.

i never really thought about checking something this simple before, thanks for mentioning it.

fowljesse wrote:After you do this, you need to do the TPS calibration again (which should be checked every couple of years, anyway).

how do you do a TPS calibration? and what is it? or is this what your mentioning here...