I had an idle problem a couple weeks back and decided to take the opportunity to replace my vaccuum lines while I was working on my idle issues. Well now I am getting a perfect idle and that I am pretty sure is a result of replacing all the intake gaskets. My problem is that I am no longer able to boost above about 3 psi. When I do boost that little bit, and let off I get this noise that has a distinct disco sound to it. You know that one sound, sort of a boooo that goes from high pitch to low pitch. Other than that it runs great! Perfectly smooth at idle and everywhere else in the RPM range. I am thinking that is probably the sound of a vaccuum line that is either detached or was torn during install and has a big hole in it. I am sort of hoping it is a leak in the intercooler pipes or elbow to throttle body junction because that would be easy to find, but I doubt it will be that easy. Any ideas? Is this an intake leak or a vaccuum line problem? Maybe a check valve is in reversed, what happens if any of them are in wrong?
thanks

 

I get that weird sound to when I start to boost but not full boost. It sounds like its coming from the stock Y-pipe/primary turbo area. I'm soon buying Efini Y-pipe and Greddy Dual Intake Kit and hopefully the sound will go away!

 

check for boost leaks.

 

Yeah 3 psi is more than likely a boost leak. Are you getting any whooshing sound? Check the accordian hose that runs from the crossover tube to the bottom of the intercooler. They are notorious for blowing.

 

what gaskets did you change? TB?LIM?UIM?

 

yes, yes, and yes. Plus a few on some of the sensors.

Good call on the accordian hose to the intercooler. I had one go a couple months ago and have a spare of the other, If that is it should be pretty simple to find tonight.
thanks

 

Take a spray bottle filled with water and spray the vacumm hoses and fittings listen for a change in the engine noise, when you hear it at least you know about where the leak is....Good Luck

 

FWIW: When I did a vaccum job on a customers car that had good boost before then had your symptoms almost exactly. What it turned out to be in my case was that i had reversed the vaccum lines going to the pressure tank,.. and the one going to the UIM with the Green/black check valve.)....Basically, I put the hose that was supposed to have the check valve in it(from the rat's nest to the UIM, not the y-pipe one), onto the pressure tank. Then put the check valve in the hose that was supposed to go to the tank, and connected it to the UIM

Have I lost you yet? ... Anyways, the results were the lack of boost and when i let of the throttle it would honk high to low pitch. I looked at an old picture of the hoses at the time of disassembly to figure out which hoses i switched. If I confused you, you can PM me your e-mail and I can send you pics of the hoses I am talking about. Hopefully That may help you out. Very similar symptoms.

 

I think Tom is referring to the Simmons drum machine sound

Does it sound like this?

http://www.anodized.com/~clayne/tomfd.wav

 

That's the friggin sound dead on Clayne!! haha!!

 

ROFL yea but slightly higher pitched lolz!

 

Exactly, more like this. (thanks Adobe Audition)

http://bud.homeunix.net:8080/audio/tomfd2.wav



Well I checked the intercooler accordian pipes and that isnt it. I did find a check valve that was backwards but that is about it. Tomorrow I will compare vaccuum line diagrams and make sure I dont have something switched. It is so annoying to have it so close yet still not working quite right.

BigIslandSevens, I understand what you are saying. I will look at that tomorrow and make sure I didnt swap one of the vaccuum tank lines with a line that is supposed to go to the manifold. I know there was a little confusion when I was connecting the tank and that side of the manifold. I could see getting that screwed up. thanks

 

Well I got the boost issue resolved. It was another reversed check valve, the one going to something related to the secondary pre-control. Now I think I introduced a new leak somewhere on the intake manifold because I am back to the initial problem before the gasket and vaccuum hose job. When I roll up to a stop, let off the gas and puch in the clutch the rpms drop and sometimes dont stop dropping, stalling out. Oh well, will have to look into it more this weekend.