I have an 06' supercrew 5.4 v8 and when I drive it then turn it off it makes a hissing noise, coming from the engine? Anyone? Almost like an airleaking noise. Hopefully nothing serious.

K.C.

 

Mine does that if the AC compressor was running when I shut it down.

 

Mine 2

 

Not to state the obvious, but do you have an aftermarket air intake on it? My 03 makes the same noise but it is the air intake still sucking air through the filter for about 10 seconds or so after I kill the ignition.

 

Mine does it to. Mine is just vaccuum in the intake leaking past the throttle body. If you punch the gas (with the engine off while still hissing), the noise goes away right away.

 

I believe the 06 has an electronic throttle - so punching the gas on that with the engine off won't do anything.

 

You're right. Fly By Wire isn't hardwired in my brain yet, even though they have been around for years.

 

That intake sound after you kill the engine isn't from sucking air IN. How could it? It's "unused" air escaping from the intake.

And yeah, if you've been running the a/c you'll have a hissing for a few seconds after you shut down..

 

I think The EVR is playing with all your heads

Sometimes those things will even hum a tune when there put to bed

 

I have the same thing but it didnt start until around 10K???

 

Good, then mine is not alone, lol. I noticed that "hiss" day one. Now I just need to find out if my 5.4 is supposed to sound like a diesel when it is idling Seriously, it sounds like a rod knocking, but it has less than 450 miles on the clock.

 

No, it's not supposed to sound that bad - I'd get it back to the dealer ASAP.

 

It's not sucking air in. It's atmoshpheric pressure rushing into the low pressure inside the intake until the pressure equalizes.

 

Theres something else it can be, I bought a 1999 zx2 as a daily driver and it did it after I bought it. It would make a slightly whistling noise while idleing and whistle down after the motor was turned off. Turned out its was the PCV valve and it wasnt letting the preasure out of the crankcase right. Dealer replaced it and not a sound since.

 

If you have the ingnition on with the engine off then the throttle body will still work/open. You can hear it. It makes a humming noice.