Boost fluctuating at WOT / Puck possibly fluttering?

[Rustyregal]

So my car was running better than ever at around 20psi. Decided to add one of my last modifications an RJC downpipe. After installation I began to notice that no matter the pressure setting (15-25psi) when my boost would peak it would begin to fluctuate. With lower pressure the fluctuations were large with a variance of 4-5psi. When I moved up to 25psi it would peak then fluctuate 23-25-23-25-23-25 and so on. Also as an added side note it spools archaically slow until 10psi then comes in normally.

Now on to what troubleshooting I've done:

-Replaced all of my actuator lines and tywrapped
-pressure tested and leak down tested my actuator
-Installed an RJC boost controller

Will of the above with no change. Then I removed the downpipe and noticed that the puck rests WAY to one side of my watsegate port. Apon closer inspection it looks as though exhaust gasses are escaping at the bottom left of the port. The imprint on the puck shows how offset the contact patch is. I'm wondering if its able to put leverage on the edge enough to lift it and cause the fluctuations I'm seeing. Any ideas are welcome as I'm at the end of my rope. Has anyone ever encountered or heard of this?

 

[TurboDave]

I'm amazed at the tiny little wastegate hole on that housing!!! I'd be opening that up!! I don't see enough evidence of leakage to make a difference.
How fast are these fluctuations occuring?

A graph display of boost from Powerlogger would be extremely helpful. Sorta like this:

 

[Rustyregal]

They are pretty rapid. Let me find the file and I'll upload it.

Posted from the TurboBuick.Com mobile app

 

[Rustyregal]

Here's my log from that night. No knock or anything. My friends said you could hear it and see the nose lifting up and down.

 

[87geeinn]

The placement of the puck is just fine. Don't mess with it.

Are you sure you didn't hook the RJC boost controller up backwards?

Remove the RJC controller to take it completely out of the equation for now and run it tuner style. Also, put a decent amount of preload on the wastegate arm. Report back.

 

[Rustyregal]

Sorry I didn't list it but thats been done also. Still fluctuates. At 25psi im pulling about .375" to get the rod on.

Posted from the TurboBuick.Com mobile app

 

[Rustyregal]

Also I had the RJC hooked up with the in line fitting going to the compressor and the 90 to the actuator. It basically being a check valve I assumed the ball side went to the compressor.

Posted from the TurboBuick.Com mobile app

 

[aminga]

looks like a miss to me

 

[Rustyregal]

But it was running like a top right before the pipe install. Thinking about putting the stock back on open ended to see if it stops.

Posted from the TurboBuick.Com mobile app

 

[aminga]

turn off the A/F correction in the chip and see if it does it again.

 

[Nick Micale]

Having seen this issue many times over the years, the first thing I would do is replace your waste gate actuator.

The spring inside may have become weak due to age and fatigue, and your new DP is allowing more exhaust flow.

Many times we have seen the W/G open on a dyno pull, sometimes as low as 13 psi. At its limit, the boost will fluctuate as it is opening and closing.

I have replaced about 5 waste gate actuators just in the past few months.

A simple check for this issue is to wire the W/G closed, and try it out - carefully!

 

[Rustyregal]

The actuator is new (5000m) but I have a standard I can test with. I got a new HD actuator when I purchased the PTE 5831.But I have witnessed plenty of "new" equipment bad right out of the box. I'll give it a try. If I wire the gate closed then I may not be able to hold peak boost where its fluctuating or am I missing something.

Posted from the TurboBuick.Com mobile app

 

[Rustyregal]

It's supposed to rain for the next 2 days straight here in south Ms. So I'll get back on it asap. Thanks for the help folks.

Posted from the TurboBuick.Com mobile app

 

[Rustyregal]

So I've done the following and still no change.

-Changed Actuator with new HD unit
-Installed New stretched SLIC
-Ported my WG hole
-Replaced WB sensor with known good spare
-Replaced MAF with known good spare

I cant find what it is. I'm kind of at a loss. No matter what I do the logs are the same. I've search this site over for more answers. I'm working out of town for the next three weeks and home on the weekends. I may try new plugs and a fuel filter change this weekend. It just stumps me that everything was great before I installed the DP. Oh well I'll eventually get it.

 

[5280GN]

Did you ever figure out the solution? I am having the same issue on my car.

 

[Rustyregal]

Not yet. I just kept it under 20psi. I blew a head gasket and I'm wondering if that was it. If I ever single it out I'll post it up.

 

[SCOOBY DOO]

A head gasket on its way out will cause flutter.

 

[5280GN]

I put more preload in the wastegate and found a vacuum leak. It now fluctuates 1-2 psi tops.

 

[TurboBuRick]

Looks to me like fuel pressure is osculating.

Rick

 

[Rustyregal]

Well I just left for offshore. My heads should be ready when I get in. I tried 2 different regulators. New HD actuator. Ported my WG hole. Different styles of boost controlers. The list goes on and on. But I'll find it eventually.