Boost spike, and creep
 

I have an internally wastegated IHI RHB5 with a 2.25" exhaust system.
I got a homemade boost controller and am trying to set the boost to hold a steady 9 psi. I teed off the FPR, which my BOV is also teed off from.
Woudl having the WG vac line teed off from this source cause spike? since it takes a while to build up pressure in all those hoses? Its a fast spooling turbo, so it spikes to about 10 psi before settling to 8, then after 5000 it creeps to 10 psi.

Any ideas?

Re:Boost spike, and creep
 

10 isn't too bad, I have one of those on my Toyota and it is hitting 11-12 on a cold day.

The IHI are really fussy about the actuator orientation, if you've rotated the compressor housing at all, you need to make sure that the rod is at a hair over 90 degrees when fully open, you can test this with an air compressor set to about 20 psi if you have access to one. If the rod is not straight enough it will bind and will not fully open.

To fix you can try rotating the compressor housing a little or re-drill the actuator mounting bracket. You can also try adding a washer to each bolt where the actuator bolt's up to the compressor housing, this will give you a little more travel, less spike, but also a bit less boost all around. I did the washer trick and it dropped my spike by 1.5 psi, and without spike I'm at about 7 psi. I used those same washers that are used to hold the compressor housing on with the little 8 mm bolts.

Neil

Re:Boost spike, and creep
 

DO NOT T off the fpr whatsoevar :-X get some 5/16" plastic Ts' and T off the PCV valve and/or the charcoal emissions filter vac/boost ports on the intake manifold, they're the biggest vacuume boost sources. i bet that's the reason for your problems. plus i also bet your fpr isn't putting out as much fuel as if it was on its' own without anything Td' to it.

Re:Boost spike, and creep
 

thanks for the help guys, ill let u know!