idling funny and sound on shutoff

bumpskier45

Registered User
Just got back from having my fmic installed and it looks fantastic by the way. my idle has slowly but surely been creeping up in the time it takes after I push in the clutch. For example when I come to a stop normally my car use to drop down to 800 rpm's or so and now it stays a hair below 2k and slowly over 30 seconds begins to drop once its down to normal it stays there till I hit the gas again and the process repeats itself. I am not sure if the next issue is related or not but now I get a hissing sound like a semi letting out its break pressure when I turn the car off,any idea's? randy K who put in my fmic says bypass valve,he said to post here and see what you all think.
 
Just hissing or like a honking or gurgling sound too?

When it's all warmed up, what happens to the idle if you remove the electrical connector to the IAC?
 
no its for sure a hissing sound only lasts a second or two,I have not tried disconnecting that,I will try that when I get home later let you know the results.
 
There is an air leak somewhere. Was the IC pressure tested before install? Check all clamps and connections. Maybe spray them and see if idle picks up.
 
no the intercooler itself was not tested before install,however there are several couplers where it could possible leak,I doubt any of the welds are bad. what would I spray it with carb cleaner?
 
If you spray carb cleaner, the computer may simply adjust/smooth the idle faster than you can try to detect a vacuum leak.

You can either start inspecting/replacing vacuum hoses and checking IC connections, or you can put compressor air into the system and then check for leaks (wet down joints with soapy water, etc.). Search here on threads that cover the details.

Have you been able to pinpoint where the hiss is coming from yet?

But yeah, I think you have a vacuum leak that was introduced w/the new FMIC, so start there.
 
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it sounds like it is coming from the raised top,but its the same top that was on before the new fmic was installed so im thinking its a connection right to the the top which is a rubber bootie.I will make a check of all these things when I get home later on see what I can find.
 
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