HIIIIIIISHHH sound when turn off the engine....Mustang GT

[tequila4me]

Hi ! dear DiabloSports Friends!!

First let me congrats all you..cause you´re doing good and fame is coming from all arround the world!

I have a mustang GT 2007 V8 3V 4.6 L, It has K&N Cold Air Intake OffRoad and Borla Agressive Mufflers. Yesterday I decided install diablosport Tune...so I bougth Diablo predator 7145...I couldn't update it cause some usb-serial cable issue ( I assumed), but I did not worried cause I read at a post..that a new update was just for sheby 2008.

I runned diablosports tune...(previusly OEM K&N CAI selection)......After back up ..my stock tune...of course!.....then I start engine...the first thing I noticed...was RPM at iddle..going up and down from 500-900 but..just for secconds..from time to time....

and then...when turn engine off...just a second after engine off...I hear a Shhhhiiiiishhh sound......I dont know where it comes....Is tha normal?? with diablosports tune?

I should remark..I´m at Venezuela...and here there´re two type of gasoline 91 and 95.....actually I´m filling the tank up with 95...

Could you have any answer for this issue?...do you think I should get my my car back to stock?

Thanks of lot for your answers!!!

have a good day!

[Talerno]

Do you have your air conditioner on? maybe the fan was running and is stopping?

[mikel]

Yeah, this is most likely not tune related.

Thanks

[tequila4me]

Hello Mike & Talerno:

Well A/C is off....but if is on...sound is same...Must be tune related...cause that sound doesn't show without tune....last night ( with help of friend who turned engine off)...I could see closely...that sound comes from K&N air intake......I was told (people other forum) that sound is normal when diablosport tune CAI K&N....So I expect to clear this issue...

Best regards

[billki]

Hi Tequila4me,
I would make sure that all the connections on the filter and air intake are making a good seal and ask that you send some of that 95 octane to us in Washington state USA, 92 is the best we can do here. good luck figuring out the noise.

[tequila4me]

Hehehe! Billki..... ...I could tell ...95 is very good here...I´m going to states next month... but I don't think is e good idea to get in to a plane with gasoline bottle..hahahaha ......about connections...I re-checked then again...and everything looks ok ....is strange....that sound appears just when engine off...lasting just one or two secconds...and its very easy to hear it at filter...like a globe lost its pressure......the car is running great!...but I don't have peace on mind..with that issue
Cheers

[tequila4me]

Hey Mike!...I hope you give me some advise....thanks

[marvinmadman]

What you are hearing is vacuum sucking air in through the throttle body after its killed. Normal for a car with a Cold air intake.

[tequila4me]

Hey Marvinmadman!

I think you' re right!!!...Thanks of lot!!!