I have replaced all the rubber, ICV is new, both MAF o-rings and R&R'ed the intake, so it should be sealed up good.

I measured my intake vacuum, today, engine warm: ~19.5 in/mercury, dead flat. When the ICV cycles, the vacuum level dips slightly, and it whistles.

I have disconnected the crank vent system (free vent with two hoses from the tower, cam cover vents capped), and removed the venturi Y-connector, so I think the manifold vacuum may be higher than stock?

IIRC, the 85-86 ICV is different than the 87-up. It uses a stepper motor, versus a solenoid.

 

Since the majority of us buy these things used and in relatively poor operating condition, could it be an issue that the whistling is normal? Or could it be a situation where the whistling happens if the ICV/ISV isn't perfectly positioned?

 

I can't believe that it would be normal, it's pretty loud.

It makes me think, though, maybe if I reset my idle speed at the throttle body, I can make it quieter.

 

Wow...not bad. Kind of like those playing cards that we used to click in between the rear tire spokes of our bikes, so that the spokes made this flicking sound on the playing cards, "BDDDRRR! BDDRRR!"

Yeah! "BDDRRR! BDDRR!" "VROOM! VROOM"

....Whatever

Mike

 

I've owned a number of 85/86/86.5 and never hears a whistle. My current 85 does not whistle or do a jig.

 

Ken,

I had a problem with my intake side boxes coming loose after a few thousand miles, then I had the bright idea to tighten all of the intake manifold clamps with the car warmed up. Everything is more flexible that way and it all gets sealed much better. No more slippage. This might be the right way to do it, I just don't remember reading or hearing it anywhere.

 

I see a lack of talent in your cars, H-miler.

Mike - I'll try tightening all the (100+) clamps when warm.

 

Now that's pretty Low, and here I thought we were friends

 

Trying to change the idle speed at the throttle body has proved a fruitless endeavor for me.

 

Porsche built the air leak into the intake as a safety precaution that you might have too good a combustion ... simple routine maintenance will ensure that the whistle is maintained in pitch.

 

That would explain why my car drives my neighbor's dog nuts!

It's gone ultrasonic!

 

No, he is just envious.

My 928 does not whistle either - probably because it is an 82 model. I have hopes it will display other musical talents & so earn enough to cover the maintenance bills.

In hope

Marton

 

your car is far to quiet if you can hear a wistle in the engine bay.

hey Ken just drop a muffler or 3, I bet you wont notice a wistle any more.

 

Ken, did you ever figure out the whistle? I cannot figure out mine. Same deal, intake refresh with new orings, intake boots, isv, etc., etc. I have fiddled with pressing on the various tubes as well. Since I saw you at SF11, I have checked and re-checked the rubber intake boots. I used a 10mm vacuum tube to my ear to try to pinpoint the whistle. It seems like it is coming from somewhere around the DS T-pipe. Thanks.

 

Same here Ken.... whistles dixie and I cant figure out where its coming from either... Let me know if you figure it out