I think my wastegate actuator is bad, at WOT is hits full boost then my boost drops at about 5.5k, what could it be?

 

How far does it fall off?

 

pretty far, almost all the way

 

By "almost all the way" do you mean "about 11 PSI"?

 

When you say that, "...it hits full boost...", exactly how many PSI are we talking about, and in what gear? How do you control boost(MBC, etc.)?

 

its at the stock boost right now and it drops down to like 6-7psi =/, like it feels like a pinto when the boost drops

 

Have you done a boost leak test yet?

 

ya its all fine

 

I would say boost leak is the likely culprit... you may be able to hit 20psi at 3500RPM, but your turbo is flowing the most CFM at high RPMs, around 6500RPM.

WGA doesn't seem to make sense as the cause of the problem... even if it were being subjected to raw boost (ie, no MBC or boost pills), the actuator should stay closed until 10.5psi, so if you're dropping to under 10psi, I don't think the WGA makes sense... double check all clamps and piping and re-do the boost leak test

 

If the boost is dropping below 11lbs you must have some sort of leak. I'm not saying thats your only problem, but I would try to sort that out first before you start replacing parts.

 

Yeah it could be a boost leak of some sort. Do an actual boost leak test. check all the boost/vacuum line fittings for tightness and secure with zipties. Sometimes the line to your boost gauge can pop off. I've had them pop off both at the nipple on the back of the gauge and at the source where you "T" into the factory line.

I'm still not clear if you are using an aftermarket boost controller or the factory boost control solenoid. In either case check all boost/vacuum line fittings for tightness.

The wierd thing is the drop in boost to a level significantly below the usual factory 10-11# base wastegate setting. I hope it's not another case of a failed wastegate flapper valve weld. Whereby the wastegate port in the turbine housing is constantly open due to the flapper valve separating from the pivoting arm's shaft.

The most likely scenario however is a boost leak. Possibly a leak somewhere between the turbo's compressor discharge and the thottle body.

 

ok ill do another check when i get a chance and let everyone know what happens, im planning on taking a trip to GST motorsports here soon hopefully this week to get retuned so hopefully they can just work out all the bugs for me.

 

Do you still have the intake snorkel? If so, makes sure the little plastic rivets are still in. If they are not, it will get sucked up into the hood at speed and will suffocate the car and the boost will drop like you are describing.

 

no i have a hks drop in

 

But you still have the plastic intake snorkel correct?

This:



See the two plastic rivets at the mouth? Do you still have those?