Ok so i have an 03 MCS with 111k on the odometer. i got this car bone stock about 8 months ago. Yesterday i installed an autometer boost gauge to track my progress and make sure im putting out the correct amount of boost. Which should be around 13-15 PSI with my mods. After installing the gauge im getting at max 8 PSI when damn near redlining and when i am coasting i get about 25 HG in. Vacuum.

I have ordered new alta silicone couplers for my IC and as well ordered the DT BPV because these seem to be a main issue for others with low boost. Any help would be appreciated.

Other info: I feel no loss in power whatsoever but i also could have had this boost leak from the beggining.

Mods listed below in sig.

 

If you feel no loss in power is the gauge reading correctly ? Where did you fit the vacuum hose. What does vacuum read at idle ? Maybe a small boost leak

 

Sounds like a slight boost leak. Your HG readings sound healthy, and if your car is peppy and not sluggish, it seems more in line of how the gauge was connected. Check the line going into the back of the gauge. Sometimes after sitting in a position for a while, the line can kink. Maybe check the line going into the vacuum connector you used to t off. That might not be connected securely. Of course with 111K, you might want to think about changing out the bypass valve too.

 

Remember than a small crack in a vacuum hose can be closed by the vacuum of the engine but when put under boost and the hose "swells" the boost can leak out. It actually does not take a very large hole to loose a couple PSI

 

ill do the idle test today i changed out a pcv hose cause it was cracked but im really thinking its the BPV cause the way my guage acts it shows let offs like its not fully closing and opening correctly. Will post vac at idle tonight.

Ty all for your help if any more ideas i would really appreciate.

 

My gauge was an autometer boost/vaccuum gauge i installed with the DIY provided in the forums all my connections were double checked no kinks anywhere . My gut feeling is i have had this boost leak since purchase

 

You probably did. It doesn't take much to get a leak on these cars. It's probably the BPV, but since you ordered a new one and intercooler bellows, do the swap. About two months ago I was only registering 8psi of boost. I removed my intercooler and checked the vacuum t for my boost gauge. It was dry rotted!!! I changed it and was back to 17psi at WOT. Anyway, keep us posted

 

my idle vac is 17 hg in installing altas couplers today when off work will post results. I hear slight whistle when WOT just before my boost drops. still unsure cause it is high pitched like the SC.

 

ok so installed Alta couplers pain in the ***! my boost is more stable up to 8 with them but nothing more.

so while I had it apart I checked my bpv I took a pic its spring was weak and it was 1/4 an in. open. so will show results of bpv when received and installed next week. Omg I hope it fixes this.


Ty all for help and input!

 

How did the bpv install go? Everything good?

 

all is well 16lbs of boost my car is killer after dt bpv install