Wumpa

hey guys i just had my exhaust manifold and O2 housing changed to aftermarket ones
and now my evo 9 only boosts 13psi when before the manifold and O2 housing was changed it was boosting, and is tuned to boost 20psi.

i have disconnected the line to the actuator and taken it for a drive and it still only boosts 13psi can anyone help me out with this?

egis

Exhaust manifold leak?did you put new em gasket?torqued properly?

Wumpa

it looks ok it was done buy a mechanic and its all been installed with new gaskets and sealant

impact blue

iTrader: (1)

any codes?check for boostleaks,maybe the wastegate is shot,when I shot a code I though I had a boostleak come to find out that the computer went into safe mode and wouldn't let me go past a set boost figure cause the mass airflow sensor went to hell.

High_PSI

iTrader: (50)

Me thinks your Waste-gate hasn't been hooked up. Stock Pressure is 12 PSI so no boost control will result to spring pressure, or 12 PSI

Wumpa

so just got my car back and think its got the mechanics stumped, they checked the waste gate over and everything else and with the gate fully closed they could only get 15 psi max out of it so they have put it down to the flow of aftermarket exhaust manifold not being right so guess ill get another set and see what happens

sparky

iTrader: (1)

A couple things: you have changed exhaust gas pressure and flow through the turbine housing, exhaust back pressure and thus the pressure differential between turbine inlet and turbine outlet. This reduction in exhaust pressure in turn impacts the overall pressure differential across the turbo itself. That is the turbine does less work than before to produce x amount of compressor outlet flow or manifold boost

You are going to have to adjust wategate spring pressure (preload).

sparky

iTrader: (1)

Since you didnt do the R&R youself on the manifold/turbo/O2 hsg. We cant know if your mechanic disconnected the actuator assembly from the turbo at some point. He may have done so if let's assume that manifold-flange fasteners were seized, or if he left the compressor side connected to the inlet pipe and split the turbine housing away from the center housing. To do so he would have had to disconnect the actuator rod from the flapper valve pivot arm in which case the mechanic may have not reset wastegate spring pressure to the same level it was set at before he did the removal.