Alright when just boosted my d16z6. got a
.42/.43 turbo
cast mani with poor wg placement
knock off tial with 4psi spring
greddy type s bov
440 injectors
crome chipped p28

now when i boost first of all huge spike i spike at 10 constantly. the answer to this problem is the wg placement obviously not getting enough exhaust gases to escape.
now the second problem..
ok im getting on it sometimes in 1st but mostly in 2nd and 3rd gear and at like top end of boost and 5500-redline it kinda cuts out. so today i went on a back road so i could do it again and look at my boost gauge and wideband. when it happened i kept the gas pedal down to the floor and i lost all boost and it was reading vac and the car felt dead. I let off the pedal and car starts running normally again.. so possible causes...

Spark plugs? Replaced with ngk ones
MAP sensor? Still running stock map head was good to 11psi (Possible im hitting the max?)
just relized one more thing after i just took pics.. this sensor thats suppose to have vacuum connected to it what is it? connected to the back on the manifold(Pic posted)

i dont know anything else i can think of so through somethings at me that would cause this.. my first guess is the map sensor but dont wanna through money for a map right now if it isnt that. Needs a clutch desperately to save its life lol.

Please post up if you need anymore info to help you out on a cause but im leading towards map so let me know

 

I'd be more inclinded to think that your engine is cutting out as your reaching the max boost the MAP sensor is can read. 1st I'd find a way of trying to keep the boost within the 6psi you want. You won't solve the wategate problem without replacing your manifold but maybe if you use a 3psi or less spring then your boost spike might decrease. Just a suggestion. But you should avoid cutting corners on vital parts like that.

 

well im planning on a full build with ram horn manifold and new internals but just trying to fix it for now

 

The manifold design works fine, you should be able to hold steady boost with that wastegate placement unless your running a HUGE turbo.

I'd look at your wastegate and check for splits in the diaphram.

Are you sure you have a 4psi spring? Thats very low, i haven't heard of 1 that low.

 

yea its a small yellow spring rated at like 3.8psi.. i took the top off and nothing is split its fine. Heard from alot of people that this design is bad cuz you dont get enough exhaust gases out to keep the boost level steady.. but idk.

Anyone know what that sensor is in the second pic? could be a reason?