okay so i just bought an 05' evo 8 MR the boost gauge wasnt working. i replaced the vaccum line runnung to the intake manifold and the gauge reads 12psi of boost on a 4 gear pull.. stock boost is supposed to be 15-16psi spikes 19.. why is mine so low? could it possibly be from a tune?

 

boost leak!

 

im hoping thats what it is. i need to do a leak down test asap! are there any other possibilities other than boost leak?

 

did u check the mbc?

 

other possibilities include wga, exhaust leak before the turbo, boost controller or stock solenoid, and vacuum lines. check all of those, and the turbo for shaft play and you should find the problem. also if the car is stock from where the previous owner returned it to stock more than likely they didnt put the "boost pill" back in. search boost pill and you can find numerous threads about it and where it goes. thats more than likely the problem.

 

tb seals/boost leak/ vac leak/ bov leak/

 

try a different guage if everything eles checks out

 

i dont have one right now. but i used a turbosmart mbc and it eliminated the problem... so obvs the mbc is my next purchase. lol

 

the guage wasnt the problem. i tried an auto meter guage and that read 12psi.

 

Most likely a boost leak, also be sure to check all of your intercooler piping and boots! is there any kind of whistling or hissing while in boost?

 

12psi is wastegate pressure. If an MBC fixed the issue then you're just lacking the boost pill.

Do a boost leak test while you're in there though, never hurts.