Wastegate testing

I fixed all the boost leaks on my car (cant find any more with vfaq.com intake tester) and I can still only run 11 lbs. Ive got a hallman MBC, 1g bov, UICP.

I was wondering if It could be my wastegate. Does anybody know how to test the actuator without disconnecting the actuator vac line?

OK! I just disconnected my acuator can line and my car infrequently runs high boost (I ran up to 16 lbs). When I accelerate slowly and let the boost stay constant at about 10 lbs, I hear a really loud leak, and I cant run over about 11 lbs. If I accelerate quickly, I can run high boost, but (like I said) infrequently.

I know this is either a problem with my actuator spring or my WG valve leaking. Anybody have any ideas on how to test my acuator b4 i take out the turbo to inspect my WG valve.

theres really no way to test the actuator, either it works or it doesnt by not being able to controll boost. Money has it that its you spring or somthing in your waist gate. Your probably gonna have to take the turbo off if you want to try to fix it, or you can just by an external waistgate.

What turbo is this on. Mitsu turbos have WG actuators set to around 9-11 psi. With the MBC disconnected and teh vac line straight to the actuator, you should be able to hold this boost all day. It shoudlnt go any higher, and if it does, its boost creep or boost spike, depending on what it does. If it holds that 9-11 psi fine, then the actuator and WG are working fine. If you cant get any more boost with the MBC, or get too much boost and ccant turn it down, then there is something wrong with the MBC or its plumbing.

With the cav line disconnected you should be running as much boost as the turbo will support. Since you only got up to 16 psi, something is wrong. And it would have to be a very large leak!

If you didnt plug the WG vac line when you removed it from the actuator, that was also a leak. You should do the leak test outlined in the intake section at www.vfaq.com.

You can test the actuator by putting compressed ar on it. With a tee in the line and a pressure guage, you can watch it and see what pressure it opens at. Actuators do fail on rare occassions.

If this is an external gate, replace the information above with whatever spring is in your external. The spring pressure determines the lowest boost you can run. When troubleshooting boost problems, I always remove the boost controller and run the vac line from the manifold right to the actuator (internal or external, doesnt matter). If it doesnt hold spring pressure there is something wrong. This will also tell you what your boost spike and creep are if any. If this test works out, there is something else wrong. If it fails, it could be the WG system, or something else. In your case a large leak will do it.

Good luck.

This on on a T25 (stock WG). I ran the boost up to 16, and Im sure it would have gone higher, but I didnt want to hit fuel cut. When I took the line off the actuator I FORGOT to plug the vac line that I disconnected. Im gonna disconnect my MBC and hook the vac line straight up to my WG and see wut happens. Thanks

I just ran the car with my actuator vac line disconnected and plugged. The boost went up to about 20 at 3/4 throttle and it would have gone higher.

But! If I drive the car at about 1/2 throttle and try to hold any boost, it wont hold. At one point, I slowly accelerated the car and It wouldnt even hold boost past about 5 lbs! (the boost would hit about 5 lbs or so, then I would hear a big rush of air, and it would go down to about 0, then boost would climb a little bit, and It would do the same thing), but when I punched the gas, the boost would climb forever.

Kevin, when you say, connect the WG acuator line directly to the manifold, I dont know which line your talking about? Should anything be connected to my bcs other than the wire plug? Im kinda new to this turbo stuff >_< Thanks

you got a huge leak somewhere...

The WG actuator hose goes from the actuator to a boost/vacuum source.

Stock setup is WG to a tee to the turbo, the other side of the tee to the BCS (or MBC).

Kevin meant run a lone hose from the actuator to the intake manifold. This way the only boost you will run is actual wastegate spring pressure. No BCS/MBC to give you extra boost.

I think I see where the confusion is. You will not build full boost unless you have a high load on the motor. That means full throttle. You can build some at less throttle, and may even build full boost at say 80% throttle... With no boost signal to the WG actuator, you will run as much boost as the turbo will support. Maximum shaft rpm, maximum flow, maximum pressure. So be careful when testing like this.

Run a line straight from the manifold (BOV line, P port on the throttle body, etc), or the nipples on the compressor cover if there is one, to the WG actuator. Like JoeWagon said, the purpose of this is to verify that it will build boost to WG spring pressure, and hold it to redline. On a t25, you're looking at ~8 psi. If it starts to creep up at high rpm, thats boost creep, and is likely normal, especially if you have upgraded the ehxaust.

If all seems acceptable in this test, hook up your MBC again, and raise boost to where you want it set. It should reach that full boost before 3000 rpm (assuming 2 liter and t25), and hold it to 5500. For most cars, the t25 wont hold more than 13 psi to redline. My car did a little better, some do a little worse. This is normal. Dont bother trying to run anything over 16 psi on a t25 on a 2 liter. Smaller motor, the t25 is good for a little more boost.