For the purpose of testing car under no boost and for other reasons, what is the best way to rig a wastegate open? My personal situation is with a Mazdaspeed Miata that has a manual boost controller. I dialed it all the way down and it is still making at least 4 or 5psi (didn't venture beyond that). I have heard of wiring open the wastegate but I'm not sure how exactly to do that.

http://www.flyinmiata.com/projects/i...s/IMG_6379.jpg

The above image shows the wastegate on my car (slightly modified). Do I need to rig something up to pull that rod back? Reason I ask instead of try it first is it's currently somewhat tricky to get to.
Or, do I need to take the wastegate off and remove the spring?
Thanks in advance.

 

Not sure if there's an easier way but this is how i'd do it.

Remove the C clip on the actuator arm located on the exhaust housing side of the waste gate. this will allow free movement of the flapper. I'd then take some wire and tie it in an open position using a nearby structure as support.

The reason you're still making boost even with your mbc all the way turned down is because your boost controller doesn't determine the minimum boost you can make but the maximum boost (within limits). The wastegate spring determines the minimum boost which is i'm guessing 4-5psi.

 

Thanks, that's helpful. I can't seem to get the wastegate actuator arm off the flapper. It hits the exhaust when I try to remove it and just won't come out due to lack of clearance. I spent a bunch of time trying to rig it open with the actuator arm still attached with no luck; that's a lot of force you have to overcome.
Ah... I'll keep trying.

 

You could loosen the actuator pot bolts till the pre-load is gone, then it should give you some play to pop off the C-clip.

 

I might be a madman but what I ended up doing is rigging up a compressed air can at 20 psi to the wastegate actuator. It's fully open at 15 psi but I figured 20 psi should be safe and allows for some leakage. If anyone else does this remember to block off the vacuum line you just pulled off the actuator. I bought a couple feet of 5/32 vacuum line and a 1/8 to 1/8 npt to hose barb fitting for my air canister. Boost came on very slow and would only hit 4 psi max. This is perfect for my needs at the moment.
Pros:
Simple and easy if you have a compressed air canister that will work. You don't have to remove anything except one little vacuum line. It works.
Cons:
If you leave it that way a long time maybe you'd wear out the actuator spring? I also don't like the idea of having something under the hood that isn't bolted down. Air could leak out and it would fail, but if your fittings are good it shouldn't.
In these two images you can see the flapper move position.

 

Unclipping the wastegate actuator arm seems a lot easier and safer to me.

 

Won't come off, I tried for longer than I should have. The C clip comes off easily enough but there isn't enough clearance for the arm to come out without bending the flapper or taking the actuator off which on mine at least has some very rusty nuts I don't want to touch. It butts right up against the exhaust. I don't know how they even put it on.
I'm mechanically retarded by the way and would vastly prefer to never touch anything under the hood.

 

The compressed air can will theoretically work, but it's a very rube-goldberg and unstable solution. One small leak that you don't notice and you'll go from wastegate open all the time to wastegate closed all the time. If you need to disable the turbo, removing the clip and using wire to hold the door open is a much better solution -- just don't drop the clip.

That said, there aren't many reasons to do it, you're usually better off just keeping it out of boost with your right foot.

--Ian

 

Seeing your photo makes the issue a little clearer; I, and most guy's were probably picturing a typical Garrett set up, which takes about 1.3 sec. to pop the C-clip off. That does look like a shitty design. Good luck with the fix!