PDA

View Full Version : Boost falling off

Silvia_Drift
06-17-2010, 07:18 PM
Hey guys. I'm having trouble with setting my boost. I want to set it for 19 psi but the boost is always falling off at high rpms. It usually falls off around 6600rpm and higher.

I have a HKS adjustable wastegate actuator so I tried bypassing the boost controller and adjusting it through the wastegate and the boost drop off was even worse.

I also tried playing with the gain and set gain values (Greddy Profec Spec 2) but that didn't do much.

I also fixed all of the boost leaks and while this improved response, the boost still falls off.

Could this be that the actuator is not good enough for the higher boost setting?

My setup:

Redtop SR
GT2871R .64
BC Step 3 cams
Greddy Profec Spec 2
s13silvia123
06-17-2010, 09:30 PM
get your motor tune
bb4_96
06-18-2010, 08:18 AM
what do you mean by falls off. be more specific.
jspaeth
06-18-2010, 10:17 AM
I had this problem, and it turned out to be a slice in an intercooler coupler causing a boost leak, but my fuel/spark were just fine bc I am on MAP sensor.

Check for boost leaks
Silvia_Drift
06-18-2010, 10:17 AM
what do you mean by falls off. be more specific.

The boost will hold steady at 19psi until I get to about 6600rpm. From then on all the way to the 8000rpm limiter, boost falls off to about 15psi before I hit the limiter.
jspaeth
06-18-2010, 12:50 PM
The boost will hold steady at 19psi until I get to about 6600rpm. From then on all the way to the 8000rpm limiter, boost falls off to about 15psi before I hit the limiter.

There are a few things:

1) Boost leak (i had this and it only caused boost drop off at high RPM)
2) Wastegate flapper can't stay shut enough to hold boost
Silvia_Drift
06-20-2010, 09:45 PM
There are a few things:

1) Boost leak (i had this and it only caused boost drop off at high RPM)
2) Wastegate flapper can't stay shut enough to hold boost

Checked for boost leaks. The whole system is mint with no leaks.

If the wastegate flapper can't stay shut, that would be a problem with the actuator correct? I don't think the actual flapper mechanism could be bad because it is a brand new GT2871R .64.
Carbomb
06-20-2010, 10:18 PM
get a external gate. and never worry bout it again!
my buddy had this issue...then he went ext