Element

iTrader: (5)

Got my ported throttle body and LS6 intake installed last weekend, and having a bit of an issue with the throttle body. In order for the car to idle regularly, the set screw for the at-idle blade position has to be almost completely flush with the throttle body casting. However, when the engine is on, the throttle seems to "stick" - almost like there's a vacuum inside the intake that makes opening the throttle body difficult. When the engine is off, there's no problem in opening the TB via the cam on the side; however, at idle, it's very difficult to do by hand, and takes a good bit of foot pressure to "pop" it open. Bringing the idle set screw up a little farther fixes this problem, but causes the car to idle at 1000rpm at idle, and when coming to a stop in neutral, a 1800rpm. The car also idles along - without my foot on the gas - in 5th gear, at 45mph comfortably if the set screw is raised enough to prevent the blade from sticking. I believe that's because the screw is high enough to allow excess air in around the blade, not just through the hole in the middle, because the blade doesn't sit exactly perpendicular to the TB housing.

I'm out of ideas on this one. If I raise the set screw to keep the blade from sticking, the car idles and drives like ****; however, with the screw down to allow it to idle properly, the blade sticks to th point of making it very difficult to start moving from a stop without spinning tires, because of the throttle force necessary to break the blade loose from the vacuum-lock (or whatever it is).

C5XTASY

Out of curiosity, who ported your throttle body?
Ed

Element

iTrader: (5)

Bo White. The TB itself is beautiful, and due to a scheduling conflict (I was out of town for work when he tried to call), I haven't been able to directly talk to him about the problem, but that was my fault.

Bo White

iTrader: (59)

When I assemble TBs, I set the center of the blade were the screw is when someone recieves it. If it is lowered, the center may not be perfect so just loosen the blade screws and center the blade in the housing and retighten. The thing about your post is you said the screw is almost flush with the housing, that would be really low and would seem to me like the IAC o-ring is missing or some type of vacuum leak. If this is the TB I think it is, in your e-mail you sayed that at first it idled fine but got worse and that is what I was plannin on helping you with but we've been playin phone tag

Element

iTrader: (5)

Yeah, with work being as busy as it has been, I haven't been getting out of the office until about 8 or 9, and have an hour drive home. Makes it really hard to get ahold of anyone :\

Here's two pictures of what I mean about the set screw (the blade itself is centered up in the housing, as far as I can tell, using a flashlight behind the blade in a dark room - light only shows through the hole in the blade with the screw set this way):




I'll go and check the IAC to make sure it still has an o-ring on it. Haven't heard any hissing or anything like that from the engine bay, but I'm not really sure where it could have a vacuum leak at.

Bo White

iTrader: (59)

Thats not too far from were I put em. I flip the screw over and screw it all the way down like that, put the blade in and center it and back the screw out about a half turn- this pretty much puts it at the stock location on most TBs. You should be able to see a crack of light all the way around the blade, if you cant then the blade is bottomed out in the bore and when you start the engine the vacuum pulls it tight and thats probably were the sticking at idle is commin from. If it idles good were you have it now and you cannot see any light around the blade then theres gotta be a leak somewere since there is no air going around the blade. The bleed hole is 5/32 or so and the IAC can only compensate so much so air is commin from somewere but were is the question . I called ya and left a message, Ill be at the World of Wheels after 3 and I will have my cell on me then.

Slammed99s10

iTrader: (11)

Did you reset the TPS yet?

Element

iTrader: (5)

If I can get a few minutes off work around then, I'll try and give you a call back. Think it's a vacuum leak now, just absolutely no idea where at. Guess I'll be pulling the intake off again sometime next week to see if something is loose.

Element

iTrader: (5)

As far as resetting the ECU after the intake/TB install? Twice, if so.

Slammed99s10

iTrader: (11)

No not the ECU just the TPS itself, had to do it on the shaner s2 I had installed.

1. Set the idle screw so the blade doesn't stick
2. Unplug the TPS sensor plug from the TPS sensor
3. Turn the key to run but don't start the car
4. Turn the key off
5. Reconnect the TPS sensor plug

That should cure the problem, it did on mine at least.

Element

iTrader: (5)

Done, didn't make any difference. Still idles high while the car is rolling in neutral, and still takes for it to idle down after blipping the throttle.

Other than the small vacuum line on the rear, and the large brake booster line, where could I have a vacuum leak at?

TheBlurLS1

iTrader: (8)

Did you fix the blade sticking? I was going to suggest what Bo said about centering the blade on the shaft. Mine was tweaked a little bit for a while and had the exact same problem as you.

Did you indeed check to see if your IAC o-ring is installed?

Element

iTrader: (5)

I'm waiting for it to stop snowing (or at least slow down a bit) and I'm going to go out and pull the TB off the car, bring it inside, and recheck everything on it - the IAC o=ring (that's the top sensor, above the TPS, correct?), and make sure the blade is centered.

The sticking problem, I fixed by bringing that set screw up just a bit, so the blade doesn't get vacuum-locked. However, that just causes the idle problem to become exaggerated. Fix one problem, and the other pops up

Slammed99s10

iTrader: (11)

Resetting the TPS sensor should fix the idling problem, the reason why it's idling high when you turn the set screw so it doesn't stick is because the TPS sensor is showing the throttle is open (probably between 2-5%) so the ECU thinks your steping on the throttle some.

Element

iTrader: (5)

I'll try that again when I put the TB back on. Not too worried about it right now, since I can't drive the T/A in the snow, and my truck is coming out of the shop on Monday. Makes it a lot nicer not to have to rush and worry about getting the LS1 running by Monday.

TheBlurLS1

iTrader: (8)

The air pressure is evenly distributed across the bottom and top of the throttle body blade, and on both sides. There is just as much pressure trying to open it as there is trying to close it. This makes the think that you dont have a vacuum lock problem, as i have never heard of this before, and can't see it happening.

I believe the problem is more related to the blade hitting the bottom/top of the TB. When you take it off and look, i bet you'll see some marks where it's been hitting. If you loosen the screws, you will be able to slide it around quite a bit, try in in a spot where you dont have any scratching. Remember to put a little blue loctite on the blade screws when you're done, don't want one of those bad boys coming loose

Element

iTrader: (5)

The only reason I think it's vacuum-related is because, when the engine is off, the throttle body open up just fine - no sticking or anything. However, as soon as the car turns on, it gets really hard to open up. I'm going to try and take just a tiny bit of material off the top front end, and the lower rear edge of the blade, to try and round it off a bit - might be getting stuck due to the sharp edge there. Also going to try resetting the TPS and ECU again, and centering the blade (if it isn't already).

Hopefully I can get this ironed out pretty soon.

Bo White

iTrader: (59)

I have sold all of my cores but will round one up that is a 98-99 style that I can send ya until we can see whats up if need be. We will get it straightened out one way or another. I would send ya mine but mines been modded for my cam and would idle high on yours.

Element

iTrader: (5)

That'd definitely be an option, if you didn't mind doing it. Going to stick the TB back in tomorrow and see what happens with a completely reset ECU and TPS, and if she's still idling funny, go from there.

Fedge

iTrader: (3)

I'm having the same problem with my BBK 80mm....would these fixes help me? I set the screw up and I have the same idling issues...i unplugged the IAC altogether and that got rid of the high/wandering idle in neutral or coming to a stop, but it still sits at around 1200 rpm when the throttle doesn't stick anymore...it's a royal pain