So normally my vacuum gauge reads 18-20 at idle.

Today as well as last friday I started it up and it read 15-16 at idle.


Last friday when this happened I got to my destination (work all night) and turned off the truck and went back out later and started it up and it was normal. 18-20.

This weekend I drive to work and at idle its at 15-16 but i havent gone out there yet to see if its still going to read that.


What does it mean when the vacuum goes down below the normal 18-20 at idle?

Truck drove fine, my wideband was great it didnt say i was lean or anything. Everything seems okay but the vacuum gauge.

Any info would be great
Thanks.

 

Leak?

 

well i think i do have a leak.

i can hear a loud hissing sound by the boost controller.

when i push down on the **** to adjust the boost the hissing noise goes away.

but ive yet to see if the vacuum goes back down to normal.


i would agree that less vacuum means a leak. but its not a leak thats affecting too much. truck isnt bogging down or anything.

is it okay to bypass the boost controller? and just connect the 2 vacuum lines on each side of the boost controller together?

 

this may help. http://www.secondchancegarage.com/public/186.cfm

 

all these views and no other suggestions?

thanks for the link but im pretty sure i have a leak, i just want some other opinions on a boost controller, I dont know for sure if the hissing sound is normal or not.

 

for those who are wondering what the problem was... since theres 80+ views and no one seems to have any idea about how to read a vacuum gauge.

Paralyzer - thank you for posting that link it is very helpful.

now to the problem.

it is a leak thats for sure, a boost controller does make a hissing noise but the hissing noise mine was making was beyond LOUD and was actually the culprit here.

I vented the top port of the wastegate and disconnected the boost controller from the vacuum source and capped off the vacuum source.

Vacuum is now correct.

SO, new boost controller was ordered and i recommend anyone with forced induction to have a vacuum gauge along with their boost gauge.

I would have never of known there was a problem if it wasnt for the vacuum gauge.

 

you have a vacuum leak... thats why

 

yes but what i did not know is that a boost controller can fail and cause the leak.