JakeFusion

iTrader: (7)

I think the IAC hole on the FAST 102 is way too small for allowing in enough airflow for large overlap cams. Has anyone taken a dremmel to the IAC hole to enlarge it vs drilling a hole in the blade?

thunderstruck507

iTrader: (18)

There was a thread where a guy drilled the hole in the iac port from .4xx" to .5" and along with dremeling the opening port and exit ports said it helped. The thread was in the tuning section but I don't recall the thread title. If you search for my threads in that section and this one, I am fairly certain I linked it to my threads.

I ported the opening/exits on my 90mm when I had it and it helped some

jimmyblue

iTrader: (11)

Not on the 102, but I had to redrill my stock TB after
filling the port on that, 3/16" (per net.advice) was too
small and 3/8" made the motor quit surging. There is no
downside to maxing out the passage, the IAC plunger
-wants- to be in control of things.

JakeFusion

iTrader: (7)

Yeah, I'm thinking it may need it. I ordered HPTuners and it'll be here tomorrow. I figure there is only so far I can open the TB and if the IAC counts are still bad, I need to open up the IAC hole. I'd rather do that than start drilling the blade...

thunderstruck507

iTrader: (18)

If you compare the aftermarket ones to the stock one you will see quickly it "can't be too big" unless you make the hole go past where the blade seals to the housing.

They are definitely finicky. I'd like to try the Pro Flow on my car but I'm afraid of losing low end power as I do a good bit of autox and with the auto that means I need some low end grunt in 2nd gear so I'm not shifting back and forth between 1st and 2nd.

01ssreda4

iTrader: (96)

Took me a few tries to get my blade set right and a tad bit of tuning but I have no surge. I personally feel drilling the hole out is a bandaid for someone not wanting to spend a little time. Even as a rookie tuner I bet you can figure it out if you try.

Pharcyde50

iTrader: (11)

How much overlap? I got mine dialed in. May need to crack the blade some and enlarge the holes on the TPS.

I've heard the Fast throttle bodies can be hard to tune due to a small iac passage. My NW 102 was pretty easy to get the counts good.

JakeFusion

iTrader: (7)

16 degrees of overlap.

Martin told me the IAC hole is too small on the FAST and to get the NW. I think I can adjust the IAC hole and get the counts where I need to.

But I need to log the TPS voltage and IAC counts. Right now, it's me adjusting the set screw, resetting TPS, and seeing what it does. I'd like to be able to get it somewhere between 1-2% open throttle, reset TPS and verify my voltages aren't putting me in a different table, and then see if the IAC counts are doing. I figure it'll take a couple of tries to get it right.

But I know the VE tables need adjustment. Right now it has a very gnarly smell that makes me taste metal in my mouth after I walk away from the car into fresh air. So I guess it's running lean? Doesn't smell like raw, unburnt fuel. I don't know what the timing is at. But I would assume it wants something in the 20-24 degree range at idle @ 212.

I also plan to take the idle down in steps from 1200 to 600 with the scanner and see what it does. If I can get it to idle at 600 after I play with timing and fueling and EOIC, then I think I can get it to idle wherever it makes the most rumble and offers the smoothest transition.

Pharcyde50

iTrader: (11)

Sounds like you're on the right track. Hp Tuners is a great help with a wideband. Once you get the counts logged you can mess with the TB and TPS. Probably wanna get the Russ K idle config to set your RAF also.

If you have to adjust your TPS to drop the voltage a soldering iron works great to elongate the holes.

I'm running a olsd tune and have it dialed in great with 14 degrees of overlap.

The timing has a lot to do with the rumble of the cam also. I run around 18 degrees at idle and it sounds great.

JakeFusion

iTrader: (7)

I had it tuned on the street with a wideband about 3 weeks ago, but the tuner hasn't been able to make it back over. So the VE table should be close. But it needs to be logged cold to see what idle is doing. I decided I wanted to learn and got HPT since I could probably log and fix this; it would just take time. I plan to run the Russ K idle config file and go from there.

I also am going to go ahead and order me a Wideband so I can make sure the VE table is close. I'm running OLSD right now too and plan to keep it that way.

Billiumss

iTrader: (11)

Not to start a debate, but GM spent millions of $$$ and thousands of hours on R&D on the LS development, there is a reason there is a hole in a stock tb. The hole helps the iac do its job better.

So many people get so bent over adding a little hole in the blade especially on the FAST TB. When someone can prove to me that GM screwed up and should have never put a hole in the tb blade to begin with then I will change my thinking.

There are a lot more tables that need tweaked to help will surging besides the IAC table. Timing, fueling, maf, idle, etc.

Why try to reinvent the wheel, round is round.