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Discussion Starter #1
ive had a boost issue for the past month and a half now and cant really figure it out.
I. When the cars just sitting, at a light or lets say im waiting for someone, the idle will drop down from normal 800-900 rpms to 500-600 rpms and play around at that rpm for a few seconds, VAC levels also fluctuate from -20hg to about -15hg, then what sounds like my SAI (hear a vacuum like noise coming from engine bay from the underside of intake) will kick in and my idle/vac will jump back up to normal for a few minutes till the idle/vac acts up again again.
II. When at WOT its gets funkier..other day on the highway i left it in 6th and put the pedal to the floor (normally spike at 23ish and hold at 19ish psi) and now spike around 20psi and it fluctuates from 20psi down to 15psi and jumps back and fourth between 20 and 15 psi. it wont hold steady.
- Ive checked all my boost lines and vac lines running from the turbo to the intercooler and everywhere inbetween and found no leaks or cracks or anything that could be an issue. Im basically lost since this issue came out of completely no where and idk what else to look for or look at. Ive been hearing that my N75 may be the culprit but im not too sure how the N75 would do this to the car. maybe? idk...
-Last week i had coilpack 3 die completely and i was misfiring in cylinder 1 so i replaced both with OEM replacements. No longer misfiring. Did NOT resolve boost problem. (not sure if this couldve played a roll in my boosting problems.)
any help at all would GREATLYYY be appreciated. for those who bothered to read all of this THANK YOU VERY MUCH.

car info: 05 Gli. unitronic stage 2, 3" turbo back, cheesed box w/ k&n panel filter, 007 valve, TIP.


Modified by LaXdUB at 9:24 AM 5-31-2009
 

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mine does the same thing but it will throw mine into gimp mode. im thinkin mine is an o2. maybe you have a bad wastegate?
 

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the boost jumping around from 20 psi to 15 psi is probably the n75 valve, i had the same problem. have u replaced the coolant temp sensor they can cause some weird idle problems though it sounds like u have a vacuum leak ?
 

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Re: (racin2redline)

im in the same boat
 

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Discussion Starter #7
Re: (pgk2004)

have not replaced the coolant temp sensor. been meaning to do this but you know...lol. and i figured it'd be either boost or vac problem. this car is really weird casue now at WOT it doesnt bounce around....it just holds at 20psi, no spiking or anything. just holds there.
my idle problem is still occuring. addressing the N75 valve, which would you recommend as a replacement to the stockie?
 

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Re: (LaXdUB)

underneath the right side of the intake mani theres 2 vacuum lines right next to each other. ones the fuel pressure regulator the other is for the n112 valve for the sai pump. the hoses are made really crappy with a braided nylon, so its possible there leaking. either would cause a weird idle problem and a vacuum leak. and with the boost holding at 20 my car did the same thing once in a while but most likely its still shot. i have the n75 J and my car goes into limp everytime i do a 3rd gear pull. ive heard pretty good things about the H (ecs one) i hope that helps...
 
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