16g wastegate not working properly

[93talonkid]

I recently installed my 16g, its not an MHI, bash as you please , but it seems to be alright, its fully ported and the wastegate actuator that came with it broke on accident, friend dropped it and broke the little port off of the actuator. ever since then its like its not working, i will hit 23 and 24 psi so i replaced it with a 14b wastegate actuator, no avail. and then i replaced it with an MHI 16g wastegate actuator off of my old one( it took a shit) and its still ####ing up. i cant figure this out.

 

[ddavisaf]

Sounds like the vaccum line to the wastegate is bad. Have you looked at it for any damage? If the wastegate can't sense any vaccum it won't know when to open, or will open much later due to faulty readings.

 

[93talonkid]

i've replaced the lines numerous times, i even disconnected my MBC and ran the waste gate to the J pipe to run wastegate pressure, it helped, it will hit 11 psi, and then eventually go up to about 20+ psi

 

[kenamond]

i've replaced the lines numerous times, i even disconnected my MBC and ran the waste gate to the J pipe to run wastegate pressure, it helped, it will hit 11 psi, and then eventually go up to about 20+ psi

Might be creep.

Do a boost leak test with a line straight from the j-pipe to the WGA and see what pressure the WGA starts moving and how far it rotates the lever on the turbine housing when you get to like 15psi (should be fully extended by then). Some of these actuators only turn the lever about 30* at full extension, and that's "normal" (but IMO is the reason for most evo3 creep problems).

If that seems to work okay, disconnect the actuator arm from the lever on the housing and make sure you can turn the lever easily with your fingers. This insures that the test below will tell you something helpful.

If that works, do a test run at full throttle with the WGA arm still disconnected from the lever and see what boost you reach. If it goes over a few psi, it's creep. If it goes to 20+psi, it's definitely creep.

 

[93talonkid]

but i've put on 3 different wastegate actuators/arms

 

[kenamond]

but i've put on 3 different wastegate actuators/arms

If it's bad creep, you could take the whole flapper out of your turbine housing, and you'll still hit 20psi. You say your turbine housing is fully ported, but some folks only port it out to a wider turbo/mani gasket but don't port out the entrance to the WG hole. Many vendor-provided port jobs are like this, too. I'm not saying that your port job is inadequate, but that is often the problem, so it's worth mentioning. The test I suggest where you disconnect the WGA arm from the housing lever tells you a lot about WG flow through your turbine and O2 housings. If the flapper has nothing holding it shut, the turbo shouldn't boost. If it does, the flow out the WG passage isn't adequate, and the exhaust is still "choosing" to go through the turbine wheel, thus generating boost - and you get creep.

As for the WGA, the stock MHI EVOIIIB16G WGAs have a very short throw. That means that it's only turning that lever a small amount and therefore only opening the WG flapper a small amount - definitely not anywhere close to 90*. That makes creep an even bigger problem, because the exhaust has a much harder time getting out the WG hole with that flapper blocking the path.

Go take a look at the turbo porting article at www.vfaq.com. They have a picture where you can see the exhaust gas "stains" inside the turbine housing on the downwind side of the flapper - they are tan. It shows how far that particular turbo's flapper was opening which was maybe 30*, so the exhaust was hitting the flapper and slamming into the divider between the WG passage and turbine outlet passage and leaving those stains. Numerous threads on this forum discuss the short throw of some of these WGAs. That's why I suggested doing a boost leak test with the vac line going from the j-pipe to the WGA. That will tell you how much your flapper is opening under full boost.

There are a bunch of posts on creep and the limited WGA throw. Take a look around and see what others are saying, but this is pretty much an "in a nutshell" of what they'll be saying.