NeverT00fast

iTrader: (4)

I changed over to a Fast 90/Ls2 setup along with trickflow heads, the car is surging more than before at 1500rpm and when I clutch in the idle drops real low and the car wants to stall.

I got it tuned and it's still pretty much the same, but my tuner told me it's because of the bigger valves in the heads that' making the overlap more noticeable. (I'm using a ms3 cam.)

Did anybody notice this issue when you switched over to a Ls2 TB? And what did you do with that vent tube coming out from the pass. side valve cover? I have a breather connected to it right now until I figure out what to do with it. Could that be causing the rough idle??

NoMoreFWD

iTrader: (1)

Try capping off the vent tube at the throttle body. If you have a breather hooked to it, it's probably causing a huge vacuum leak.

NeverT00fast

iTrader: (4)

The LS2 throttle body has no provision to take the vent tube from the pass. side valve cover like the LS1 TB, that's why I'm not sure where to route the tube back to.

I tried tapping back to the intake but it made this loud whistling sound on decel, and the car would barely idle. So I just stuck a breather filter on there for now.

NoMoreFWD

iTrader: (1)

Actually re-thinking your situation, you should be ok with the breather on there, since it is drawing air before the throttle body. I would check to make sure you don't have any vacuum leaks anywhere around the intake, as you stated the problem started after the new intake and heads. Surging is a classic symptom of a vacuum leak. Otherwise, it may be improved with more tuning.

Sigforty

My LS2 TB does have some surging, but I have a big cam so it is expected. The only thing that is slowly learning on is the TB hanging up a 2k rpms till I stop. The more I drive the car the more it goes away, and the surging appears to be taking the same road as well. Now for the valve cover hose. Terry over at Futral drilled a hole in my plastic intake tube and placed a threaded hose barb. The hose was changed out for a longer piece and routed into the intake. There is no problems with whistling on my Z06 with that setup.

JakeFusion

iTrader: (7)

Port the LS2. Stock it'll run pretty rough - it needs some work done to it. Once that happens, it's the best TB out there and it'll help alleviate your issues with part-throttle surging.

NeverT00fast

iTrader: (4)

You're talking about the airbridge right?

I have a pretty big cam too, I know the surging will probably always be there. But I want to get rid of that dip in the idle, my tuner said I can get rid of it if I go to speed density tune.

NeverT00fast

iTrader: (4)

Where on TB should I port?

Sigforty

[QUOTE=NeverT00fast]You're talking about the airbridge right?QUOTE]

Yeap, I just could not think of what it was called.

exSSer

I, too have this combo, and I'm having problems with the idle-hunt as well. My biggest bitch is the huge flat spots while off/part throttle at low RPMs, such as cruising at 70mph in 6th. I'm putting along, and the car feels like it hits a big wall of marshmellows, but as soon as I give it some gas, it runs fine. I just put a breather on the pass. side hose, and called it good. However, I've been told that it needs to have metered air (air after the MAF) and not outside air. In addition, I've sent the TB off to Tony Mamo to work his magic. I'm also adding a catch can to the PCV line. When the TB is re-installed, I'm gonna tap a fitting somewhere in the airbridge to feed the pass. side valve cover, instead of just using a breather. I'll see then how it runs.

NeverT00fast

iTrader: (4)

somebody suggested drilling a hole on the blade also, but wouldn't that in turn raise my idle since vettes are fly-by-wire?

NeverT00fast

iTrader: (4)

Ok am I missing something here? Vengenance told me to drill a hole on the LS2 TB blade, they said my old stock TB had a hole on there but I'm looking at pics(I sold my TB already) and I don't see a hole on there. But it looks like the stock TBs on Fbody has holes on them, do the holes only come on the Fbody TBs??

miami993c297

iTrader: (6)

No hole in my TB Blade,
No surging or bucking,
Idle smooth as silk and steady at 900rpm ~50rpm,
Coming back to idle anytime like stock,
Steetability very close from stock,
Using HP Tuner in OLSD.
And my cam has a lot of overlap.

Christian
PS: I recently tried a hole in the TB Blade, that was not the solution...for my set up.

ACG

iTrader: (1)

My 02 camaro came with a hole in the stock throttle body

[IMG][/IMG]

miami993c297

iTrader: (6)

Hi NeverT00fast,

Are you Fly by Wire as my 2002 ZO6 or cable commanded??

In FbW no need of drilling the TB Blade, no IAC count...

Christian

Sigforty

No hole drilled in the stock ported TB that came off my vette. The hole will increase idle air, but you would need to adjust the throttle blade to account for this air to keep from idling at 2k.

vettenuts

iTrader: (4)

One issue you have is not having the PCV inlet in the air inlet system. By introducing a breather, you have also introduced unmetered air, i.e., it isn't going past the MAF but it is going into the intake. You need to plug your PCV inlet line, previously on the TB, to the air bridge behind the MAF. This may not solve all your issues, but it should help.

NeverT00fast

iTrader: (4)

I have a 03 Z06, so it's FBW. So your car has a SD tune??

NeverT00fast

iTrader: (4)

Very interesting point, I thought the same thing too. But Vengenance said that the pcm controls the idle speed so it'll still idle at 900rpm with the hole drilled.

NeverT00fast

iTrader: (4)

I was thinking about that too, I think i might have vacuum leak? I'm going to retap the inlet tube into the airbridge, should I run it through a catch can while I'm at it? I already have a catch can.

Also going to check for leaks around the intake runners by spraying carb. cleaner around the intake. And pull the intake out and put some RTV on the map sensor, as it was pretty loose in the hole on the Fast intake. Plus port the LS2 TB.

IF all that fails, I"ll probably either drill that hole or go to a SD tune.