Simple Ways How to Test for a Bad Wastegate Actuator:
- Stretch the Wastegate Actuator Rod Open with Your Hand, While the Wastegate Actuator is In this Position (Open position) Then Put your thumb Over the Nipple to not Allow air to Leave the Wastegate Actuator. If The Wastegate remains in the Open Position, then that means that the Wastegate Diaphram is Still in Perfect shape. (If the WG is Tightly close but diaphram blown air Past or doesnt hold vacuum, this causes Full Boost Condition.)
- Check for Binding of the Wastegate Rod when the Wastegate Actuator is Mounted. Often the wastegate actuator diaphram can be Crushed Causing the wastegate rod to get stuck on the wastegate frame. This is more of an alignment issue with the wastegate actuator. (Usually This Condition Causes the Wastegate Door To be In Open Position When the Wastegate is Mounted, Causing Lag and Little or No Boost.)
- You Should be able to Apply air Hose Pressure to a Wastegate Actuator to have the Wastegate Open and Remain Open Without Leaking air our of the Diaphram.(If Doesnt Open Full Boost Condition can be the Result)
- Broken or leaking Wastegate Nipple (Causes full Boost Condition Because the Boost Pressure is not able to open the Wastegate Relief Valve)
NOTE: Usually a Bad Wastegate Actuator Means Little or No Boost or Full Boost Conditions.
NOTE: If You see Boost Spike Above Target Boost, The Way to fix this is to use a Boost Source as Close to the TurboCharger as Possible, With as Short of a Vacuum Line as Possible, The Spike is simply Cause By a Delay in getting the pressure of the Turbo to the Wastegate Actuator. This is not a sign of a Bad Wastegate Actuator.
NOTE: If You see the You Reach Your Target Boost, Then See that your Boost Creeps from Your Target Boost Level When the Engine is Turning Higher RPM 4500 or Above, this is not a sign of a Bad Wastegate Actuator. The Reason This is Happening, is because the Wastegate Flapper hole and or passage after WG Hole will not Flow Well Enough To Control The Boost Level, This Can Be Fix By Porting.
But if too Much Porting is Applied, Then You Could have an issue with not being able to run high boost, Because The Exhaust Pressure Gains so Much Ground On the WG flapper, that The Exhaust Pressure will force open the WG Spring Before the Pressure To the WG Nipple is Applied. At This Point you need a Wastegate with a Higher PSI Spring Pressure. Choose the Base Pressure of the Spring by taking your Target boost and Divide it by 2. If you want to run 30psi, you should use a 15 psi WG with a boost Controller. Or you Could use a 30 psi wg without a boost controller.
NOTE: Wastegate Adjustment Should Not be Treated like a Boost Controller, Excess tension will Cause the Turbine Housing To Crack Sooner.