Vacuum leak

[trahamp44]

Whenever i crank my truck i hear a loud hissing along with the sputtering that is indicating that i have a vacuum leak.how do i fix this?i know something is not connected

 

[rburch]

Some info on the vehicle would be helpful!

 

[Thermo]

trahapm44, if you are suffering from the common problem, open the hood, look on the passenger side valve cover. You will see the PCV valve sticking out the top of the valve cover. You will also see a plastic tube running from it to the back side of the engine. Follow this tube around to where it taps into the back of the intake. The rubber seal there is prone to cracking and will cause what you are seeing. If it isn't that, then more info is going to be needed to help narrow things down.

 

[wink]

you need just a auto mechanics on this one, Even a tiny leak, as small as 0.020 of an inch, can degrade engine performance, compromise driveability and turn on your Check Engine light. Here's why. A vacuum leak is downstream of the device that measures the incoming air the mass airflow MAF sensor—which means the engine actually ingests more air than is measured and the computer gets an erroneous low reading.

 

[Lane24]

Check this link....... just expands what the others have said, and even has a picture or two.... http://www.expeditionforum.com/f27/rough-idle-p0171-p0174-heres-what-you-need-check-first-4926/