Ok, heres the deal. I was driving the car one day and noticed a sound I had never heard before. It is a hissing sound... but not when I am under boost conditions. If I coast with my foot off the gas, the sound leaves. IF I give it some gas(very light, enough to maintain current speed) the hissing sound comes back. Then if I give it boost, you hear the turbos spool and it drowns out the hissing sound, if it still exists... What the hell is it? I was just in the garage and was about to change my FD to non-seq, then I remembered that I had this problem. On another note, my boost pattern is so sparatic that is very frustrating. If I launch, the car will boost 9-5-8(or something like that) but If I am cruising in 3rd gear and roll on the gas I get like a 10-8-11/12 pattern. Can someone lead me to both problems cure? Thanks in advance.

 

Most likely a boost leak - if not from one of the IC couplers or the like, you may have a split control hose somewhere.

Dale

 

I don't understand how it could be... it is making the sound when barely on the gas....

 

Gees ...c'mon guys. There has to be someone who could point me in the right direction?

I took a listen while the car was running and if I flucuated the rpm while looking under the hood it sounded like it was coming from somewhere near the lim ccv area. But now I have it non-seq( to try it out) and it still makes the same noise.... and it almost sounds electrical

 

I have a similar problem.. Downpipe leak...
That hissing and squeling when under boost or when gasing it.

It could be your gasket, or bolt not tight enough...

 

would the loose downpipe cause low boost?

 

Sure,
I dont get any boost at all too...

 

I still can hit 12 lbs of boost no problem....I was just under there to do a non-seq conversion and it is tight

 

yeah, it's weird.. I always get boost on 2nd and 3rd... and boost on some other runs, but sometimes theres just no boost at all in 1st.

Well after all I'm still just stating my problem that could relate to your problem.
Buy a Mechanic Stethescope and go under the engine bay and tell somebody to constantly reving your car... Listen with the Stethcope to see whether you can trace that hissing down. Could be your Downpipe Gasket itself if the bolts are tight.

 

The easiest way to tell if your DP has a leak is simply start the engine when cold, and put your hand around the gasket, and have someome rev it lightly to a few thousand RPMs. You don't have to worry about getting burned since the engine and exhaust are still cold.......assuming you do it when the car is cold

A common large hissing problematic area would be the coupling between the turbo y-pipe and the pipe that attachesthat to the IC. There's a big rubber coupling there. If it is split, you will never see it. It could look perfectly normal just doing a visual on it, but pressure will allow that slit to open up and vent boost.

For starters, check ALL your couplings. If you find nothing, then you are going to have to start playing Inspector Gadget. Next step would be to begin to diagnos everything. Check your charge control valve, too.

Wait, you said that you wanted to convert to non-seq anyways. So don't bother diagnosing anything. Just rip it all off, and diagnose it once it has been simplified.

 

I replaced the coupler that connects the y pipe to the crossover pipe already and it will create the noise with no boost. The sound is coming from the ccv area. Goofy part of that is I am trying the rikki style non-seq and I still have the noise. AllI have to do to get it to make the noise is rev it up a bit(maybe 1200 rpm ) while in the garage and away it goes. I'll keep looking.......

 

Dude I got the same problem. Just put in an RX7 Fashion downpipe about a week ago and ever since then the car felt slower for some reason. Also like you say when you get on the gas you hear a whooshing sound then it stops when turbos come on. I haven't checked my ic hoses but will do so tonight to see if thats the problem. I was thinking it could also be my dp gasket since I'm using the original one that came with the precat.

 

I found my problem so I thought I'd put an end to the tread... It was the hose that leads from the lower pipe on the air pump..... it was split right beside the clamp so you couldn't see it and it was only split on the lower part. Tricky little basterd! Anyhoo, FD all better now!