Ok, so I just removed my emission on my s5 Tii this past weekend. everything went well... redid all the grounds, added new ones, new fuel lines, I kept the dashpot and thermowax. new vacum lines everywhere. also kept my OMP. Did the TB mod. after setting my idle and adjusting TPS... car runs smooth, pretty much the same as before, except it will not boost over 5psi. I used to boost from 9.5 to 10.5 psi on 2.5" exhaust. So I was wondering... is this just some boost leak? I checked everywhere for vacum leaks... none... no sign of any leak.. any advice?

 

Did you hook up the factory boost controller?

 

My car used to be N/A. I have an aftermarket boost guage. Anyways... so I replaced all the gaskets, redid the block off plates... CHECKED for boost leaks by pressurizing the intercooler piping after the turbo and the TB with over 10psi... no leaks... so it doesn't look like I have a boost leak... so I just don't get why I can't get passed 5-6 psi. I should be running 10psi-ish. I have the boost guage, BOV, and pressure sensor hooked to the same vacum source... is that too much? is my boost guage reading poorly? Can the waste gate be messed up? (still stock wastegate, not ported)

PS. The car ran great before the emissions removal... 2 days later... it runs good, but it doesn't seem to boost enought (yes, I did have a different set up for the BOV, pressure sensor, and boost guage before I removed emissions... different source of vacum)

At this point, I have no clue... and I'm very confused on what can be happening.

 

my n/a hasnt ran right since my emmissions removal. idk whats up with that.
overheats a lil now as well...

 

lol, that's not very reasuring for me :P My only problem is either a boost leak or bad wastegate or bad reading from the boost guage. (I think)

OK, so I finally decided to take the line from the actuator that open/closes the wastegate... went for a ride and I was easly boosting 10psi, 12psi... etc. Yes, I didn't blow my engine... lol wasn't trying to either... but as it looks like I didn't have a boost leak after all. So I am assuming the waste gate actuator randomly just went bad? It opens too quickly? Why not letting me boost more then 5-6 psi. Anyone have any ideas?

 

Do you have a boost controller now or what? What are you using to control the boost?

 

I don't know about the turbo cars that much but with the N/A's we have 4 vacuum solenoid switches and its all controlled by the ecu. maybe you eliminated one of those and it went to your waste gate line. maybe its stays close until it hit certain boost or certain RPM the the ecu turns it on.

the last car I turboed we got really tricky, we wired a vacuum switch to the electronic boost controller. so the wast gate was closed and un feed so it spooled up harder and quicker since its not getting pressure all the time(when the wg gets pressure all the time it starts to open at a pre set psi, but with the switch it opens when we want it to)

my advice to you is look up what was inline with the wg hose maybe it was something like that nd it was holding your wg open longer so it can boost more

 

Did you remove the all those solenoids and crap on the right hand side? One of those is the factory boost controller. The spring in the wastegate is set for about 6psi, without the factory boost controller, which you likely removed, you'll only get 6psi instead of 8-9

 

I do not have a boost controller, and I didnt before, and I used to boost arround 10 psi all the time. Right now I just let off the gas when I reach 10psi so I dont blow my engine... until I put the actuator for the waste gate back into the equation, then I won't be able to boost more then 5psi. The turbo duty solenoid is what you are talking about... that did help controll boost pressure, BUT in the emissions removal I am supposed to remove it since if your car already boosts over 8psi, then there it becomes useless anyways. And just to prove that right, I put it back on last night... and still couldn't boost more then 5psi. So at this point it just seems like the spring in the waste gate actuator is broken or something... not sure how to test that

 

The springs can fail, I've never seen it happen though. But considering the boost is cutting off at approximately the point the spring is designed for its hard to fault the spring.

 

It just seems like my wastegate is opening too fast, which is the only way I can explain why I can not boost more then 5psi with the actuator connected. What else can be limiting the boost at 5psi at this point? Unplugging the actuator allows me to boost easly more then 10psi (which I do not want)... so there is no boost leak as I have originally thought. I have a 2.5" straight exhaust on a stock JDM S5 turbo engine. Pretty much everything else is stock except the intake to the turbo, BOV, and S5 FCD.

 

You need a real boost controller then. Thats what they do, delay the wastegate from opening until you get to a set psi.

 

I got a mechanical boost controller and it solved the problem . I'm running a little over 10psi again. thanks alot for the help.