Wastegate actuator problems

On the greddy kit, I've had nothing but problems with it overboosting. It's been getting worse lately. Kpro is saving my motor but it's shooting up past 7psi (upwards of 15) very fast even with quarter throttle.

Sometimes it will work fine, I thought I had fixed it but it worked for a week. I replaced vacuum lines, even tried the test to see if the actuator opens at 7psi with an air compressor and it does... So I'm quite confused

I recently switched the actuator arm and boost gauge on it's own vac*** block from the pcv intake manifold port (installed a catch can) to see if that would help in any way, but no such luck.

Can anyone tell me a potential issue that would cause this, and a way to fix it? I cant pass anyone on the highway without hitting my 12psi boost protection wall.

Sounds like boost creep caused by the manifold since the actuator is working without a problem. But then again it could be a few things. Are you running an electronic boost control solenoid?

Nope, I had a manual one but it didn't help. I went back to a straight line. Would it be the manifold or the greedy downpipe causing this? I have 3" kteller exhaust but I haven't seen any 3" downpipes that are internal wastegate friendly.

What's a decent boost cutoff for this problem? I set it to 9psi which isn't helping my case but I'm afraid of causing any damage. It has been professionally tuned a long time ago, and I know that can be a difference in judgement in this case. I think he originally had the cut set at 15psi but that seems excessive and it was hitting it.

Any changes to the car since the tune? Ie:changing cam angles in kpro, cams, change in diameter of exhaust, silencer in muffler taken out, major weather change, did you move to a different altitude to sea level? I'm just rambling on things but some if not all of these can effect the boost level. I know you tested your acuator...but for shits n giggles have you tried a different one?

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None of that, other than the cold winter but it's been doing it before that. Unfortunately I don't know anyone with another actuator, and ri junkyards never have anything good. I think I've maybe seen one Rsx in the many ones I've gone to haha. I called greddy a while back to see what the issue could be, they weren't really helpful and quite rude. Honestly the last of their product I will own. I asked what a replacent would be from them, he quoted 250-350 not including shipping...which at that price I would go external. But money is tight right now. I would like to get the car feeling safe.

I do work at a metal fabrication shop right now and I'm checking into a 90 degree mandrel and flange ( I believe it's the same as the gt28?? Correct me if I'm wrong) since I already have plenty of scrape 3" stainless pipe at work. I haven't seen 3" internal wastegate friendly downpipes except the Natedog but I can do it for more than half the price myself.


I mean the setups been the same since the tune, stock greddy downpipe, 3" kteller into a 3" magnaflow exhaust. Maybe the downpipe is restricting the gas flow??

To be completely honest I'm not a very knowledgable person when it comes to these particular issues. I just figured throwing out some things would maybe spark your brain for possible ideas.


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What downpipe are you using? Where do you have the boost source for the actuator connected to? What is your exact setup?

:yeahthat: Where is your boost source for the wastegate actuator?