(b18b)My boost is hitting like 16lbs and it only tuned for 13lbs and is cutting out towards top end... its the first time its everhappend. car has never spike ever. has stock block head and intake 550 injectors, 255 walbro-fuel pump, hks wastegate, cast turbo header...turbo is turbonetics. I have look on alot of threads but nothing has yet helped with my problem( dont blast me to hard this is my first turbo set up i WAS a allmotor man....

 

Check your vacuum line running to the wastegate; if this has a crack/hole in it it can cause over boost problems.

 

check wastgate and everything that attaches to it.

your hitting a boost cut.

 

^^

What they said

 

checked the wasgate and everything is good... now i have come to the conclusion that its only doing it late nite when it was cold out side... during the day when its hot it runs normal no cutting out and no boost spike wtf????

 

That will happen when its very cold outside like that, especially under 40 degrees. Cooler, denser air allows for a bit more boost under those conditions. You either need to get some boost control to help on those cold days, or don't lay into the throttle so hard. That way you won't hit boost cut or spike over 13psi.

 

If it just started doing it all of a sudden then i would suspect the vacuum line to the wastegate or the wastegate itself. Maybe when its colder out the valve in the wastegate starts to stick Maybe a torn diaphram in the wastegate Double check the vaccum line first and do a boost leak test. Its just a process of elimination