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

Posted: Mon Sep 10, 2007 8:34 am
by 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! :wink:

RE: HIIIIIIISHHH sound when turn off the engine....Mustang

Posted: Tue Sep 11, 2007 11:16 am
by Talerno
Do you have your air conditioner on? maybe the fan was running and is stopping?

RE: HIIIIIIISHHH sound when turn off the engine....Mustang

Posted: Tue Sep 11, 2007 12:27 pm
by mikel
Yeah, this is most likely not tune related.

Thanks

RE: HIIIIIIISHHH sound when turn off the engine....Mustang

Posted: Tue Sep 11, 2007 12:55 pm
by 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

RE: HIIIIIIISHHH sound when turn off the engine....Mustang

Posted: Tue Sep 11, 2007 1:25 pm
by 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.

RE: HIIIIIIISHHH sound when turn off the engine....Mustang

Posted: Tue Sep 11, 2007 7:29 pm
by tequila4me
Hehehe! Billki..... :lol: ...I could tell ...95 is very good here...I´m going to states next month... :mrgreen: but I don't think is e good idea to get in to a plane with gasoline bottle..hahahaha :D ......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

RE: HIIIIIIISHHH sound when turn off the engine....Mustang

Posted: Tue Sep 11, 2007 7:55 pm
by tequila4me
Hey Mike!...I hope you give me some advise....thanks

RE: HIIIIIIISHHH sound when turn off the engine....Mustang

Posted: Tue Sep 11, 2007 9:34 pm
by 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.

RE: HIIIIIIISHHH sound when turn off the engine....Mustang

Posted: Fri Sep 14, 2007 8:25 am
by tequila4me
Hey Marvinmadman!

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