joemomma

Just for the hell of it, I checked the no load operation of my turbos. They are supposed to make 4psi at around 3k-4k rpms in neutral. Mine made 2-3 lbs. I have noticed a slight high pitched hissing, almost a whistling kind of hiss while boosting. I have always thought that was just coming from my boost gauge where the plastic line connects to it, but the other day noticed the same kind of noise coming from under the hood (It's been doing it for a while actually, but it didn't occurr to me until yesterday that it may not be normal). With a downpipe, intake and exhaust (no computer yet, since I'm stuck at stock boost anyway) my car is making between 9-10 lbs on the primary, probably 8 on the transition, although I haven't checked it lately, and 10-11 on the secondary (only for an instant, then it immediately dives to 8 at around 5200-5300 rpms, which is another problem). I know this is a pretty normal boost pattern, but if I have a leak, I still need to fix it. I have had both of the rubber couplers split on me (one right after the other) and it made a much more noticeable hissing noise. I replaced them just a few months ago so I don't think they would be the problem. Where is the next most common boost leak area? BTW, it is not my BOV confusing me, it only hisses during boosting. Also, is there a (non-life threatening) trick to locating exhaust leaks? I think I might have a very small one near the front of the car, which may also be robbing me of boost. Thanks for any help.

joemomma

Ok, I removed and checked all my intercooler/intake hoses and couplers. No problems however I saw that one of the vacuum hoses coming from the turbo precontrol solenoid was disconnected. I don't know how much air goes through that hose. Could I be hearing one of those hoses leaking? I still hear it now after I reattached it, but it was one of the few hoses I didn't replace with silicone (ran out of silicone) and is very loose. If there is any pressure at all running through it, it would probably pop right off the first time. It is so brittle and hard that I didn't bother tie-wrapping it and I don't have any clamps small enough so I'll have to wait until tommorrow to order some more silicone. If this hose is leaking, could it cause my secondary boost to drop off early (5200 rpms)? Would I be able to hear it leaking from inside the car or is it normal to hear a VERY slight high pitched hissing sound while boosting?

evot23

iTrader: (17)

could it cause the decrease? I'd say yes. I hear a slight hissing noise when I get into boost and I run perfect 10-8-10 on low, 11-8-12 on high. If you checked all the connections (did you check the one that goes to boost sensor...not your gauge but the sensor on the car) and all the hoses are fine, you may have split in a hose that isn't visible until in boost. This has happened to me and it was by sheer luck that I found it.

Good luck!

joemomma

Thanks for the response. They've been hard to come by lately, at least without having the word 'riceboy' or 'supra' in the subject line When you say I may have a split in a hose, do you mean one of the intercooler/intake hoses or a vacuum hose? I've thoroughly checked all the intercooler hoses and haven't found any leaks. Could the hissing be the secondary turbo pre-spooling? I'm going outside right now to see if the turbo pre-control hose has popped off again. It's so loose, it probably has. As long as I'm ordering silicone hose, has anyone ever agreed on who makes the best i.e. most kink resistant? I used the mazdatrix hose for the ones I replaced already and it is pretty good, but I've heard there is better. I had to make some of them VERY long to keep them from kinking. long hose=more hose=more money. Thanks again.

TOMMYY

Have you checked to see if your intercooler hoses are tightly attached? You said there are no leaks, but I was hearing a hissing sound and turned out that the clamp around the intercooler hose was stripped, it was barely noticeable to the eye but it gave me a big loss in power, plus that damn hiss nose. bought a new clamp and haven't heard anything yet.