When I first start my car, the idle is still high, the sucking sound is super loud coming from the filter. Is that right? Also my car seems to lag sometimes. I have no check engine light. Would lack of fuel cause this? Any info would be great. Thanks

 

Sounds like a vacuum leak. Did you plug the vacuum port on the throttle body that controls the THERMAC system?

-Mark W.
'88 SC Camaro w/ 305 TBI

 

Mine makes a sucking sound when it's first started up, for like 1 second. I think it's just the iac valve moving around.

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1989 Pontiac Firebird Formula LO3 Auto
-180 degree stat
-Hooker Cat-Back
-velcro t-top bag
-Wonder Bar from my IROC
IAT MOD, 3.3ohm resistor
Open element 14x3

*****Possible future mods*****
4th gen seats, fiberglass spoiler, new paint

1985 IROC-Z, TPI Auto
-Accel Super Coil
engine and tranny overhauls coming this summer


http://www.geocities.com/krt80/

 

could be lean, but the computer will compensate for that if its a problem.

if at startup its lean, you may want to adjust the pressure a minute bit. the shshsshsh noise is just because that giant black hunk of metal you just removed was also a silencer, its all normal. lag may be from increased air, and your ecu has yet to compensate by changing the fuel settings at that rpm. if its an off idle lag, you should also adjust your fuel pressure a bit. to learn how to do that, there is also an article.

other than that, sounds normal.

 

I put an open air filter on my 91 and got the same problem. The high idle is the TBI's version of a carb's choke, and the sucking sound was always there, but you couldn't hear it through the (muffler) single snokel. I set my fuel pressure @ 11-12 psi to compensate for the increased air. My car now drives fine with no problems.

 

Yeah mine makes that noise in high idle too, I heard to today. And it will still make an initial sucking sound anytime you start it too.

 

Mine makes that sound all the time. Runs fine. It is really noticable since I got my cowl hood, sounds like a blowoff valve on a turbo if you tap it HAHAHA!!!

 

would that be your 12 second car sounding like that?