my car started to cut off at 4000RPM in 1st 2nd and 3rd gear does anybody ever had the same problem???

 

yes. bought the car with a 16g, injectors, and no other supporting mods, wouldnt go over 4000rpms. I got fuel pump and safc-II, tuned it and it was all good. that may not be your problem though if you dont have an upgraded turbo.what does you a/f gauge say?

 

what happens when it gets to 4k rpms? does it just stop producing power? does it sound like it suffocating? does it sputter?

 

Well if its the narrowband then it says GREEEEEEN

 

my a/f reads regular but I have a crack on my header and it only does it in first three gears it cuts the gas so I have to shift in order to produce power. I dont have a bigger turbo or no other mods other than a MBC and BOV and I run my car about 14 psi

 

I doubt its fuel cut with your mods. Sounds like you may have a boost leak. Have you done a boost leak test?

 

no i didnt do any test at all. how do i do a leak test.

 

right in here!

 

everybody else miss this? if you have a crack in your header... i'd say that would be your boost leak! you can try to weld it shut or just buy a new one. stock ones are dirt cheap... like 15-20 bucks cheap. a new/nice one will run you anywere from 150-300.