Drilling TB blade for startup and idle
 

I have been working on my idle and start up with Justin. Lq9 233/239 .605/.595 112 cam, 11:1 with 243 heads. TBSS intake, cable driven 92mm TB. 4" CAI.

The IAC is maxed out and its still not getting enough air on start up. I have to give it some throttle to get it to start and then slowly idle it down.

He said that I need to either drill (enlarge) the hole in the TB or adjust the blade and reset the TPS.

What do you guys recommend? Ive done some reading on it and some guys like to just drill it and some suggest adjusting the blade.

It has a small hole in it already stock. Whats the best method to finding how big to go? Just slowly increase it until it starts and then readjust the tune to get the IAC steps in line with where they should be?

Any direction or help would be great.

I would adjust the blade. If the TB does not have a throttle stop set screw, it is easy to mod and add one, or you could use a shim of some sort. Using this method it is easily adjustable to get IAC counts in check and can be re-adjusted later if something changes in your setup.

I will have to check it out after work. I cant remember if there is a set screw or not. Is there a procedure for re-zeroing the TPS then? I read something like turn the key on with it unplugged for 5 seconds, then off and hook it back up and I should be at 0%.

Unplug your iac and and set your idle 25-50 rpm below your commanded idle.
Then tune it..
I was having problems with mine sticking open after a wot pass so I just left it unplugged. Idles around 900 in p/n and 700 in gear.. Been like that for 2 years

It's not so much idle, its more starting. If I crank it without giving it any throttle it wont start. I have to open it a bit and then it will idle. It surges sometimes as well which makes it die every once and a while in idle.

IS your fuel pressure regulator any good? LS motors (on a MAF tune) like between 20-30 IAC counts at a hot idle in park. If you can't get it there with the screw then slowly increase the size of the hole till you can. But be careful you can't put it back once its drilled.

Im running a Aeromotive Stealth 340 with a vette reg/filter on the TBSS intake fuel rail. I have good pressure all the way through.

I'm sure its good but what it is? Vette regulators aren't made to take that kind of volume. I would bet at an idle your fuel pressure is 20-30 psi different then at WOT. See what your actual pressure is under all conditions. If your not using a return style fuel system your fuel pressure is scaled for a constant value and it is seeing wide swings thats why your tune is off. I wouldn't wanna see more then 5 psi varience on a returnless fuel system.

Technically it still it return style as the vette filter has feed and return on it. I was going to run a Walboro 400 but that would have pushed through the regulator. I was told that the 340 is fine with the vette filter (bought it from a guy who was running the same set up for a year)

I dont remember what I was at, ill have to dig out my gauge.

I'm talking about a returnless tune, where the injectors are scaled to 55 psi. I would get a gauge on it and see how much the pressure fluctuates. Also make sure your stock fuel filter is squeaky clean if your now running two filters now like I am.