I have a custom turbo setup on my 03 Z and I am having a little boost creep issue. Here is the list of part I have ,

Precision GT35 Turbo
Synapse Synchronic Waste gate,
Turbo xs RFL BOV
Turbonetics piping, including updated waste gate relocation kit.
Rc 550cc Injectors
Utec with map sensor

There are plenty more parts but these are the parts that I think are important in this case.

So I got the car tuned on Monday and runs great. But driving yesterday and today I realized something, in first and 2nd gear the car will make 8lbs and the boost stays exactly at 8lbs., but in third gear when i reach 5500 rpm the boost will spike to 11lbs and the car breaks up. Car also did this in 4th gear. It obviously didn't do it in 5th gear when it was being tuned because i saw them take it to 6400rpm. Its strange because what gear I am in is affecting the boost creep. Has anyone heard of this, and if you have what have been the cause? Thanks

 

ok we need to know what is ur wastgate stock boost ? is it 8 psi ?

do u have a boost controller ?

the more important thing is, did u install the vacum lines in the correct wastgate port ???

when ur in first and second gears, the car will not have a chance to built boost, but thin when u go for a bigger gear, it will make moor boost, u said it hits 11psi and the car breaks up wich means ur car is making more boost.

in ur guage ull see 11, but in real its more than 11

looks like u install the vacum line in the wrong port.


can u send me ur Utec para MAP

 

TN always have that boost creep problem even with the relocation pipe. You are still using the TN pipings with just a bigger turbo.. how big is the Synapse? I think upgrading to a bigger WS help solve the problem with the TN kit..

 

Another possible thing is that certain style of boost controllers have different settings for internal and external wastegates. When I had a custom single turbo in 05 my tuner runned my motor due to having my HKS EVC set on swing valve (internal) and I had poppet (external). For some reason it was giving really inconsistant boost control then it spiked about 3 psi higher than it should have.

If you don't have a boost controller it sounds like you may have a vacuum line routed incorrectly or possibly being pinched during heavy engine load/torssion.

 

The synapse waste gate is also a manual boost controller. It has a series of vacuum ports, and depending on which spring you install and what combination of ports you use, there is a chart that shows you what the boost level you will achieve. The turbo has no waste gate.
Here is the link to the products user manual. I have the 40mm WG001 model. I have the 45lb spring installed and the vacuum port that I have my vacuum hose connected to is port c which should give me 7.7 lbs and i have not adjusted my preload on the waste gate (spring C) but what I just realized is on page 13. It says if I have boost creep to remove my 45lb spring and just use the preload spring to get maximum valve lift to bypass my exhaust away from the turbo. I have very minimal back pressure in my exhaust, I have no cats and a turbo xs exhaust. The vacuum line that I am running to the waste gate comes directly off the turbo and is dedicated only to the waste gate. I will try to get the utec para.

 

ok
that makes it easy now, u have to make sure about the wasgate stuff u talk about.

but im sure ur car is over boosting, thats why it cuts off