So I just had a shep rebuilt transmission and an act clutch installed at my local shop. At the same time I had them install a cold air intake I had. After I got it back I went from running about 20 psi boost to only hitting 10 max with my boost controller turned all the way up. Anyone have any ideas of what could be going on? Thanks

 

boost leak!

 

Are you calibrating boost with an electronic, or a manual boost controller?

 

It's a manuel boost controller it's a forge controller. I talked to the mechanic and he said the bov was in backwards so he flipped it around. Does anyone have a picture of how the bov should be connected?

 

I don't think that your mechanic is correct if he is advising that the DV being installed backwards would result in lower boost levels. In fact, that the opposite would invariably hold true. Under those circumstances boost should be higher not lower, right? . Why so? Well, if the DV is clocked incorrectly and installed backwards then the valve would not open or lift off its seat...EVER. But, what do I know. If he installed everything then that might be the source of your problem. At least you would hope that he could figure out how to orient the two ports of the DV correctly

 

What BOV/DV do you have on there anyway? Is it the stock piece or aftermarket?

 

Maybe I wasn't understanding you correctly and maybe I was too hasty in criticizing your mechanic. Maybe he is right. My apologies!

If the DV had been installed backwards before, then it had not been opening at all. Then, once he flipped it and installed it in the correct orientation now it is lifting and venting properly. So according to this scenario boost levels might now be lower than they were before when the DV had been installed backwards. Although, this would not account for the huge 10 PSI drop from your previous high of 20# down to your current level of 10#.

If your turbo's stock wastegate actuator is set up with zero additional spring pressure then that base pressure would be 10-12#. But, this doesn't answer the question as to why your MBC is not effectively able to raise the boost level any higher though does it?

I am still curious as to exactly what DV, or BOV is installed on your car?

 

bov installed backwards? I didnt know how thats possible. I thought u can install anyway as long as vacumm lines are correct. i thought its just put on the piping and wouldnt matter which way the bov is facing. What am i missing here

 

sounds like a big boost leak, I had the same issue before, turned out the IC pipe coupler wasn't fully tightened.

 

You are missing the boat completely my friend.

 

Yeah im not sure what exactly the mechanic was trying to say either. Im very new when it comes to forced induction so im trying to learn. Where should the vacume line that is attached to the BOV be connected to. I understand that vacume opens the vave but right now that tube is ran back to my intake tube before the turbo. Does it need to be ran off engine vacume or vacume caused by the intake?

 

What BOV are you using?

 

just the stock BOV for now

 

This is the setup i have now

 

I cant tell from the picture but in my opinion if it is backwards (now) then the charged pipes would be pushing against the opening and when it gets past 10-12lbs it forces it open if the vacuum is not pushing hard enough to keep it closed since Evo's run on a push/pull type BOV and it stays open during WOT, causing you not to pass about 10-12lbs.
The normal way it works is the charge pipes push with the vacuum to keep it closed then when you let off or shift the vacuum sucks it open and allows the charged air to pass back thru to the turbo.
Correct me if i am wrong but dont flame please. Just the way i thought they worked