Hi everyone I just recently purchased a used STOCK(besides intake) 2008 evo x gsr from a used dealership. Since the day I bought it ive had problems with it. I had a check engine light for overboosting, maf sensor and my cat was blown 2 days after I had gotten it.
I demanded they fixed it and they did. I got it back and it felt great. I asked why it was over boosting and the mechanic said the vacuum line under the plastic peice covering the valve cover was disconnected.
A week later my clutch was slipping like no tomorrow. I brought it back once again and they replaced it, took them almost 2 damn weeks! The day I was supposed to finally pick up my car the mechanic told me the engine light for overboosting was happening again. FML. So the next day he calls and says he replaced a vacuum line and the light is gone and the car feels much slower because its apparently not over boosting anymore.
I pick the car up and DAMN slow as hell! I thought maybe that it was just stock like that but then i realised driving on the highway with other cars and stuff that clearly there was something wrong. I buy a boost gauge install it and am only getting a constant 9-10 PSI?! vacuum sits at 20 so i know its hooked up right. Im pretty sure stock boost pressure is 19-21 then tapering off to 16 at redline correct? I dont think its a boost leak is it? could it cause that much loss of pressure without noticing it? Could it be a missing boost pill? or broken wastegate? PLEASE HELP im new to the car and just want to enjoy it! Thank you!!

 

Please someone?! Brought it to mountain mitsubishi in Hamilton and they didn't want to work on it?! Said come back when they have more time. Need some input!!

 

It sounds like you are running off the IWGA spring pressure. I would start with a boost leak test and check out the IWGA.

 

If it's anything like the older models there is probably a restrictor pill in the line that was replaced.

 

I'm currently running at .7 bar so I'm in the same boat with my 8. But I know im running of the stock wastegate pressure so hopefully a MBC between it will fix up my problem as it seems the entire stock BCS was removed.

 

Check the vacuum lines, I believe there should be two boost pills. Same thing was happening to me. Found out it was because the vacuum lines didn't have the pills.i fixed it by adding a 3 port and Cobbs stage 3 other, she's now running better