legendr35

First off,

My car makes a screaming sound when you floor it, the dB increases as more gas is given. My friend says it sounds like an open wastegate (which I have never heard) But I know it is not normal.

But to the point, so far, i've replaced the stock Y-Pipe with a efini one (all this did was stop a small, boost leak due to cracked couplers, but it did not subside the noise). Second, I've replaced the coupler that goes from the Y-pipe -> Intercooler with a silicone one, which did nothing. I've check all the hoses from the intake, and all of them seem to be good. The only thing I need to check for now is the rubber piping from Y-pipe to the intercooler. Could the second turbo be making this noise, because it is going bad? It is blowing oil, I can tell, but they have 122K miles on them and they still pull 10-8-10, plus I have absolutely no smoke.

Do you guys have an suggestions of what else to check?

Plus, I want to replace the stock studs on my downpipe with bolts, I bought some recommend by some people here, but it doesnt fit right. If anyone has replaced the studs recently, please let me know what sizes I need. thanks

Thanks in advance!

Mindphrame

Crap...i just read something about this. Exactly what you are talking about....damnit..i gotta find it...

legendr35

thanks for helping Mindphrame.

Mindphrame

After reassembling everything on the car I was getting full boost in both turbos including a nice transition from the primary to the secondary. The problem was between 2000 rpm and 4500 rpm I kept getting a loud squeal coming from under the intake plenum. I narrowed down the noise to the air control valve (ACV). I removed the intake plenum again but could not find anything wrong with the ACV. I finally received advice from Dave at Blackstone Performance. I told him my problem and he told me to open the ACV and check to see if the metal disc had slipped down a little while I was reinstalling the valve. I loosened the three nuts on the valve and sure enough the disc was not flush with the intake manifold (I could tell because it left an imprint in the black carbon build-up). I tried to pull the metal disc up with a screw driver but the disc kept falling back down. In order to make the disc stay in place, I had to remove the solenoid rack (again) and pull the valve completely off. Next, I put a little rubber cement around the disc (from the advice of Dave) to give the piece a little tackiness so it wouldn't fall off again. After reassembling everything, another sore back, and much frustration the car runs perfect with no annoying chirps.
I also learned in the process (from Dave) that the ACV is only active between 2000 and 4500 rpm which is what clued him in to the problem. I can also remove the intake plenum in about 15 minutes but I hope to never have to remove it again. Anyway, I just thought you might want to mention something about the ACV disc to save someone else the headache of having to remove the solenoid rack twice. Once, as you know, is plenty.
Chris Davis

This was off of Rob's site. Hope it helps.
Jeff

legendr35

thanks, I might try that, but my noise goes all the way till 8000 RPM..

maxpesce

Also check the alloy intake pipe to the secondary turbo - if it is loose / leaking at the connection to the turbo it can cause a LOUD screaming noise.

legendr35

thanks, already did. Is there a gasket between the pipe and the turbo?

maxpesce

I don't think so but it can/should be sealed w/ silicon form-a-gasket

rx7speed811

you probably checked/changed this already with your efini y-pipe, but maybe the hose that feeds the blowoff valve for the second turbo is cracked. a lot of times with the 3/4 inch hoses you cant see the leak until you take it off and squeeze. i just found out one of mine was cracked while doing the hose job. boost might be leaking out of the crack and causing the noise. in my case it didnt because my turbos hardly boosted at all.

legendr35

i'll check that out, thanks rx7speed

Mindphrame

any solution yet?

legendr35

well, I fixed a boost problem, my intercooler piping was loose. I get nearly full boost now, but it screams loud as hell still....I really think my second turbo is dying, they have around 122,000 miles on them. plus the leak oil. and the compressor wheel can fully touch the side of the compressor if i push it from lef to right.

Alpine

yep there is a gasket.

legendr35

Thanks alpine, I don't have a gasket there. maybe thats where the sound the coming from.

technonovice

legendr35-
Did your gasket fix get rid of the sound?

P'cola FD

The gasket is a thin metal one. It's fun if you leave it on while removing your turbos... you'd be surprised how easily it cuts through flesh.

legendr35

Yup, I put a new gasket, and it still makes the sound. I know for sure my turbos are making it...they have 128K miles on them....