Diverter valve not opening when engine is cold, how can I test it?

[rzyao]

So I've been having a turbo flutter issue for a few months now, and I think I've narrowed it down to only happening when the engine is cold, when it warms up a little it will vent properly. Does this indicate my DV is failing, and is it possible to test it somehow and rebuild it, or do I need to just bite the bullet and buy a new valve? My car runs spikes of around 18psi, and it usually flutters a little then opens up, the DV opens sooner the warmer the engine is. I have a Bailey valve of some sort, but unless it says on the unit I can't say which one. I also know that my N249 is nowhere near causing issues as I bypassed it to test and the issue still remains even with a line straight from the manifold to the valve.

Sidenote, is the Forge splitter valve any good? I'm interested in getting a little more of the sound.

[walky_talky20]

You can test it with a hand vacuum pump. Pull a vacuum on it and you can see if it opens smoothly and fully. You'd also want to make sure it does a decent job of holding vacuum and not immediately leaking it off.

With an aftermarket "piston" type valve like yours, getting contaminants inside can certainly cause the piston to bind up in the bore. So it may just need taken apart, cleaned and re-greased. This is normal maintenance for the piston type that is not required for the OEM diaphragm type.

I have the Forge splitter valve on my car. I like it. You would definitely want to run it with the N249 bypassed, as they do not play nice together. Initially you will think that all the clicks of adjustment are quite overkill. However, you will find that the correct tuning of the splitter actually requires fairly granular adjustments. Too loose and you can create an intake leak. Too tight and the piston can chatter, etc. But when it's dialed in correctly it is a cool effect in my opinion. If I'm driving a turbo car, I at least want some audible confirmation that I'm doing so. And I want the people on the sidewalk to also have this information...because racecar. Some people don't agree with this at all and think the splitter valve is silly. I see where they are coming from and can fully respect their opinion. But, personally, I think it's cool. I run one on my AWM and my brother has one on his ATW with no issues.

[rzyao]

You can test it with a hand vacuum pump. Pull a vacuum on it and you can see if it opens smoothly and fully. You'd also want to make sure it does a decent job of holding vacuum and not immediately leaking it off.

With an aftermarket "piston" type valve like yours, getting contaminants inside can certainly cause the piston to bind up in the bore. So it may just need taken apart, cleaned and re-greased. This is normal maintenance for the piston type that is not required for the OEM diaphragm type.

I have the Forge splitter valve on my car. I like it. You would definitely want to run it with the N249 bypassed, as they do not play nice together. Initially you will think that all the clicks of adjustment are quite overkill. However, you will find that the correct tuning of the splitter actually requires fairly granular adjustments. Too loose and you can create an intake leak. Too tight and the piston can chatter, etc. But when it's dialed in correctly it is a cool effect in my opinion. If I'm driving a turbo car, I at least want some audible confirmation that I'm doing so. And I want the people on the sidewalk to also have this information...because racecar. Some people don't agree with this at all and think the splitter valve is silly. I see where they are coming from and can fully respect their opinion. But, personally, I think it's cool. I run one on my AWM and my brother has one on his ATW with no issues.

Thanks for the info! I think I'll take the valve out tomorrow and try rebuilding it, and see what happens. Is there a good way to test it without a vacuum pump? I don't think I have anything I can use.

[walky_talky20]

I can't think of a good way without a vacuum pump. You basically just want to see it moving smoothly. So you can just push on the piston with your hand and feel it, perhaps. Depends on what spring you've got in there (and how strong your fingers are).

To check that it holds vacuum, you can push the piston up with your hand, then block the vacuum port. It should hold open. Release the port should close the valve abruptly.

[rzyao]

After fighting with a super rusty hose clamp I managed to get the valve out. It's just some generic Bailey branded valve, so I don't know the model. If it matters, it looked like it was covered in corrosion. When I pushed up on the piston and put my finger over the vacuum port, it did push back noticeably slower, but it's definitely not sealing, as when I took it apart, it appeared to have a little bit of tolerance between the housing and the piston. I don't know if it's missing an O-ring or something, but if it helps I can get a photo.