Weird Vacuum issue please help

stage 2+ apr
glow shift boost gauge
wide band gauge .

..i been having a very weird vacuum issue.
1) on start up or as in idle its at 19-20.. normal ..but when i am driving 70 mph its at 9-10 very low .the car definitely has lost power . i can see on my boost gauge it goes quite up to 21-22lb . then drops to 17 with out moving my foot of the pedal. note i do not punch it pedal to the floor, i keep it at maybe half pedal.. i have also seen that when i take an exit of the freeway, upon stopping the needle doesn't always drop to the 19-20 range. it at times get stuck at 16-17 . maybe there is something simple as a kink. but i just cant see one since i have not moved any lines or anything.

the car does not shake or anything, but one thing i have noticed is at around 1900-2000k RPM there is some kind of weird vibration i can hear and feel under the car. . so thats my situation i did replace my PVC valve from ECS tuning to OEM brand, but i am thinking i can go with the delete option,. . any thoughts anyone ? i would really appreciate it.

http://bshspeedshop.com/bsh-fsi-2-0t-pcv-revamp/

Check your MAF sensor mine just wasn't plugged in all the way and it caused my bov to stay open all the time and just dump any boost I made


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going up to 21-22 lbs of boost and droping to 16-17 is normal for a tuned car. k03s dont hold boost for very long at all. it just slowly drops once you hit peak. crusing 70 mph i would say 10mmhg is also normal. but idle once the car is warmed up you should see 21-24mmhg. 19-20mmhg cold is also normal. I dont think you have a problem from the numbers you posted. if you are giving the engine gas you will have less vacuum. no gas you should have full vacuum.

Vacuum/ boost description sounds normal, rattle under the floor could be the fuel line rattle. There is a TSB for it.

Alright thanks hearing that from others outs me a bit more at ease, only thing that troubles me is that I distinctly remember at cruising speeds vacuum Would be at 13-15 . Not sure what changed..and fuel line tsb. By any chance would you have a link I can go to ?
Thanks again

so as i been driving the car and i have noticed that at times my boost gauge gets stuck at about 13inch vacuum. that is even when i let of the throttle and cruise it to neutral. .that normal ? for it to not drop down to 19,20inch vacuum

phantom1209 said:

so as i been driving the car and i have noticed that at times my boost gauge gets stuck at about 13inch vacuum. that is even when i let of the throttle and cruise it to neutral. .that normal ? for it to not drop down to 19,20inch vacuum

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Could be fault Guage. All depends on the tune and health of the engine but that low of vacuum is out of spec. If I'm engine braking I'm getting close to 28 inches and idle at op temp is around 25. Stock tune and minor bolt ons.

I also had my boost tap tear and that caused a really weird Guage reading but very very little performance difference. Check that too.

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