hi guys, i have a boost issue. my evo8 was running around 23 psi, but for some reason now it wont go past 15psi. nothing has changed since then and i didnt installed anything different since then. i have a hallman mbc but doesnt mattter how i turn it, it wont go past 15 psi and its running like ****. can somebody help me out????

 

Boost leak test it.

 

1) Did you do a boost leak test (attach an air compressor to the compressor side of the turbo and listen for leaks)?

2) Did the vacuum line come off the turbo's wastegate? I believe the stock wastegate pressure is 11 psi.

3) Did you inspect your spark plugs?


-Bink

 

i will be doing the leak test this weekend, and vaccum line is still attach to wastegate. would bad plugs do that?

 

It could be plugs, wires, rarely coils.

 

i wanna figure it out before i bring it to a shop, they'll suck me dry. is there a possibility that my hallman is not functioning properly or my greddy RS is leaking?

 

There are plenty of possibilities which is why we are throwing out the obvious stuff first i.e. check all your vacuum lines. They may have all still been on but are they all intact... none torn or any holes? Did you check all your IC couplers and connectors (both sides of your IC, Turbo down pipe, mid section of pipes running from the DS of the IC up to the TB, and the TB elbow) and MAP to include the one running to your wastegate? Did the wastegate come off the flapper arm nipple, did that cotter pin that holds it on break? Is your wastegate still opening up at the proper psi, maybe the diaphram inside of it is torn... I could do this all day. What about your exhaust are you running a stock cat or a test pipe?

 

oh damn, i should just do a leak test and go from there. too many possibilities and dont know where to start. does anyone have it go down to 15psi like this?

 

The, "....running like ****...", part has caught my eye. What exactly do you mean? Could you be more specific?

 

well, after i changed the plugs it seems a bit better but still not getting past 15psi. i suspect my greddy RS is leaking bcause when i shift normal it opens up nicely and you can hear the woosh! loudly, but when it gets close to 15psi i feel like its leaking and when i shift you bearly hear the wooosh! sound anymore. im off Sunday so i'll do a leak test and hopefully i'll find something that cause it

 

Those are notorious for leaky diaphragms, I got rid of mine recently as well due to a bad diaphragm. Went with a OEM IX diverter valve. Held 28psi beautifully.

 

alright brother, i'll get an ix DV. by the way, i had the flange welded on the injen IC pipe, what will i need to get the IX DV to fit?

 

You'll have to have that flange removed, if you still have the bung on that IC pipe meant for the stock DV, then use that.

 

well here's the update on the boost issues. i did a boost leak test and found 3 HUGE leaks. one down by the LICP, one by UCIP and one at BOV flange. i fixed all of that and didnt take it out for a drive yet. i'll update that tomorrow but everybody should do the leak test once in a while. **** just get loose over time you know.

 

You should invest into some constant torque clamps as well. Won't loosen up so easily.