i have somewhat of a "whistling" sound coming from my intake. It seems to come and go during normal driving, but seems to show up more when sitting still idling, etc. running the a/c seems to make it occur more and you can hear it start and stop whistling when the a/c compressor engages, then disengages. i have run across a few articles that talk about the IAC opening needing to be enlarged, etc. and I wonder if this is what I'm hearing? Could it be that the sound is merely the high volume of air that is trying to pass thru the relatively small IAC opening?

Any thoughts?

Thanks!

Robert

 

Do you have a bbk throttle body? They had problems with that early on in production...

 

heh my edelbrock 58mm (same as bbk's if I remember?) has the whistle. Sounds a little like a blower. Doesn't bother me really but now that the question has been asked...are there any issues with this?

-Brian

 

I have an Edelbrock 52mm. And yes, it does sound a lot like a supercharger when it makes that noise...I've actually had people ask me if that's what it was. Anyway, I don't know that it's necessarily causing me any real "issues". Like I said, when I run my A/C, it seems to do it when the compressor cycles, and it does seem to me that my car just seems to hate when I run the A/C...seems to put more of a strain on it than it should for a stroker motor ya know? I mean, I can be be sitting there idling at a stop light and when the compressor engages, I will see my tach needle dip down a little and you can just tell it makes it harder for it to keep a good idle, etc. So, once again, it made me wonder if what I'm hearing is the IAC passage struggling to squeeze enough air through, and then when I turn on the A/C, it's making it even harder and starts to affect my idle a little, etc. Just a thought This has been one of those annoying little issues and I'm anxious to hear anybody's else's experiences related to this.

Robert

 

I've got an Edelbrock 52mm and have experienced the same whistling sound. If it really bothers you, you could try running with your stock intake/filter. I found that my stock piece reduced the whistling noise dramatically, but I put the SLP CAI back in. My tune reduced the noise substantially... to the point that it whistles just a little bit for a couple of minutes when the engine is cold, and that's it.

It'll whistle more when you turn your AC on because the IAC needs to flow more.

You could try opening the throttle blades a bit, so that less air has to flow through the IAC. If you can scan/log your car, what are your IAC counts? Mine are 25-30 at closed loop warm idle (currently 875rpm).

There was a write-up on Edelbrock's site about the whistling issue. Unfortunately I can't find it.

 

I've got a TPIS throttle body and K&N CAI and I have the same whistling noise. I usualy only hear it when the car is idleing. If the car comes down from idle it will settle for about .5 seconds then all of a sudden "weeeeeeeeeee". It doesn't bother me though, when my buddies ask wtf it is, I usually tell them that, unlike their 5.0s and 4.6s, these LT1s move massive amounts of air so it would be no surprise that there's a slight whistle somewhere along the intake...

 

I guess I'm relieved to hear that what I'm hearing is fairly common and nothing to really worry about. I am going to play with my throttle blades tomorrow and just see if I can come up with anything workable.

thanks again!

 

I tried adjusting my throttle blades a bit this morning, but still heard the whistling noise when idling and with A/C on. I guess it probably did make it idle a little better with a few extra RPM, but the only thing I hate about that is that you can't hear the lope as well

 

Here's an explaination of the whistling noise:

http://www.bbkperformance.com/tech1.shtml#Q8

 

check your vacuum hoses. you likely have a broken or mis-connected hose. if the AC puts a strain on the motor then it's either that or time for a new clutch assy. my jeep had problems till i replaced the clutch. i also had a vacuum leak at the same time...damn near pulled all the available current out of my battery just to turn on the defroster .

 

I built a 383 LT1 and sold it to a frined of mine, he put it into a 94 TA. I did the tune for him. For the AC i too noticed it worked the engine harder, (engine making less torque at low rpm because of cam?)

In tunercat there are some tables that if edited could help.

IAC Offset for A/C Anticipate Vs A/C Pressure
IAC Target RPM

try raising idle rpm some in drive or adding some IAC counts.

as mentioned above, check your IAC counts at idle, should be around 40, adjust your blades accordingly.

 

busta9876,

should my IAC counts be at around 40 while idling in neutral or in gear...with or without A/C on?

Thanks!