911GT2

So as I was driving around getting supplies to do the poormans non-seq tomorrow to hopefully fix my boost problem, i decided to take one more look at the full boost pattern before non-seq. So i floored it, and as the tach got near 3500rpm i heard what sounded like a saw and it was increasing in pitch. The only thing i could think of was turbo rubbing inside the housing, which could be the cause of my very low 3 psi boost after 4500rpm.
Is this noise characteristic of anything else?? Again, it sounded like a saw, but got louder as revs built, and it came intermitently, but very rapid, like on off on off on off, very quickly. So, like i said, is my turbo dead?

911GT2

Forgot to add, my boost stayed constant at 10psi that whole time, and my "normal" pattern is 10-7-3.

93TTRX7

could be an exhaust leak. I had one of the bolts on my turbo manifold come off that was causing it. Does it happen only when the secondary comes on or does it happen off idle?

911GT2

What are you talking about when you say causing "it" The noise or the boost issue?

Meiogirl

iTrader: (2)

when do secondary turbos normally hit?
i found out recently that my secondary is gone, but that was only discovered at 6400 rpms.

Mahjik

iTrader: (1)

http://www.autosportracetech.com/RX-...leshooting.htm

911GT2

Thanks Mahjik, i've bookmarked that webpage and read it numberous times before, but I pretty much gave up on sequential, and decided to go non-seq, and was planning to do it tomorrow. But, I didn't want to do that if my 2nd turbo is dead, because i assumed driving it in non-seq form would make that worse, since it would be spinning or trying to spin the entire time, whereas in sequential it will only spin in higher rpm's.

I was just wondering if anyone else had ever encountered this noise, so i would be able to know if my turbo is dead, or if it's something else.

Mahjik

iTrader: (1)

No problem, I was really posting that link for Meiogirl.

I had a problem like that last summer and it was either a mis-routing or the vacuum lines weren't connected well. It was the two vacuum lines on the firewall side of the UIM that cause my problem.

Basically, I got full primary, when the transistion hit the boost just kept going down. I knew it was my problem because I had just reinstalled everything. Those two lines were extremely short and I had a difficult time reinstalling the UIM. I replaced them with some longer lines to make installation easier and I was back into business.

Aside from checking all the hoses, you should take a look a the check valves. Personally, unless you are going to do the FULL non-seq conversion, I would just troubleshoot your current problem instead.

911GT2

I've thought about the full non-seq, the poormans was just to test it out and see how I liked it, full non-seq was in the plans.

I'll look over the vac lines tomorrow before i try out the non-seq. Thanks again.

Meiogirl

iTrader: (2)

thanks, i bookmarked that one myself.

so is the answer 4500 rpms? I am referring to the section on the Charge Control Solenoid/Valve. There is a part in the explainantion that states the secondary turbo compression is applied to chamber A. at 4500 rpms
I am confused is that a second stage to a turbo going off period, or the secondary turbo itself?

911GT2

The secondary turbo should be fully online just after 4500 rpm. The turbo control actuator (TCA) pre-spools the secondary at 4500, and just after that the charge control valve opens, allowing the boost form the secondary to be added to the primary.