Dan8289gta

So last night i tore down the tpi (pia broke 2 torx bits) and installed 4 new injectors. I got her all back together and she runs like a champ very smooth good idle ect. The problem is when you rev the throttle quickly you can hear a loud hiss and there is a delay, we sprayed around the runners and obvious possible vacume leaks with carb cleaner but heard no change in the way it ran. So anyone have any ideas on something i may have overlooked or a usual culprit?

onebluemcm

I can appreciate the teardown - I recently had to change an intake manifold gasket for a water leak.

As for the hissing sound, double check all the small vacuum lines - there are a lot to remember to re-connect and I bet one might be loose, from under the plenum or other. I guess, I'd just double check that first.
Kev

Dan8289gta

Alright guys pullin my hair out here, pissed with it for a while with no luck. Does anyone have a Vacume diagram or any good ideas, have already sprayed carb cleaner everywhere a few times and tried the rubber hose to the ear trick. I even tried to disconect each line from the plenum one by one and plug the hole with my finger and rev.

Steve89GTA

Did you use new runner gaskets?

Dan8289gta

No but the ones on there seemed to be in good shape.

D's89IROCZ

change them ...I had the same issue .

Dan8289gta

Top bottom or both, is there some type of sealer that is good to use?

Guest

Power brake line hooked up?
There's also the PCV hose to the driver side on the base.

91 camaro racer

iTrader: (2)

RTV is the sealant that it calls to use.

8Mike9

No sealant needed or called for on runner gaskets, use new ones though, they compress to seal...you notice the difference when you get the new ones.

Not sure if it's your problem or not, though...carb cleaner should have brought poor sealing to your attention.

Did you hook up the little tube under the Throttle Body?

Dan8289gta

I sprayed around the runners good with no noticable difference, and yes i did reconnect the hose under the throttle body/plenum, power brake hose, and the pcv hose.

RednGold86Z

iTrader: (1)

Could you describe the "delay" a little more? Does the hiss lag behind the throttle moving? Does the engine delay revving from the throttle moving? Does it hiss when revving up, or when returning to idle, or both? Does it really sound like the intake is hissing?

Try a length of hose put up to your ear to try to locate the source.

You still have it MAF, right, not converted to SD (and revving without an air intake - the IAC has loud flow through it)?

Since it doesn't idle really high, i'll assume you have the runners on the correct sides.

Did you remove much else besides the runners, plenum, TB, and rails?

Dan8289gta

The hiss does lag behind the throttle moving and it delays the motor from revving, it only does this when romped on . At no other time is it even noticable. O and no its not coming from the intake.Yes it is maf, and the only other thing i changed was the ignition module. I did also try the hose trick.

RednGold86Z

iTrader: (1)

Did you get the tranny's TV cable hooked up and adjusted correctly (fully retracted, then hooked up, then WOT)? Is it your transmission hissing (and burning up)? I don't think a loose TV cable will cause the engine to lag, though - from what I've seen it revs faster due the slipping clutches.

Are you romping on it by hand in the engine bay, or while driving? TV cable won't matter if it's in Park.

It's a strange problem... Does it feel like it lost any power? Did you put in 22lb/hr injectors?

Dan8289gta

It does it while in park, and i am doing it by hand under the hood, i drove it around the block one time and it just didnt feel as responsive as it should. And yes they were 22lb injectors, i also tested resistance on all of them before putting it back together, all were 16.5 ohms or higher.