I'm pressure testing my intake system as I have a leak and am only able to boost up to 0.4 bar

I have connected a compressor to where the stock airbox goes and build pressure to 15-20psi

I can hear a leak coming from what appears to be the plenum area (but cannot be too sure)

when I get underneath the car I can still hear the hissing sound, and it's at it's loudest when I have my head next to the gearbox/diff

in an attempt to narrow downwhere the leak iscoming from I have split the system into two sections

the first part I am testing is from the airbox to the turbos (I have plugged the pipe at the turbos)

when I test this section I can still hear the hissing sound so it seems to me there is a leak coming from the plastic piping that runs from the airbox to the turbos

I then tested the second part of the system which goes from the intercoolers to the throttle body

I have attached a compressor to one of the intercoolers and have capped off the other

I turned on the compressor but can't get it to hold any pressure
As soon as i turn the compressor off the pressure gauge reads zero


Am I right in thinking the leak in the first part of the system could be the plastic intake piping itself? I don't think it's the DVs or vacuum lines as the hissing sound is just as loud under the car as it is in the engine bay

I have removed, checked and refitted the DVs anyway but this has not helped

Secondly, why am I unable to build any boost in the second part of the system?
Am I supposed to blank off the F hose when I chech the second part of the system?

Am I being stupid here, or is there something I have overlooked?

Thanks

 

I have also tried spraying all the hoses with soapy water but this hasn't helped
I still cannot trace the leak(s)

 

I would make sure you have a leak first...are you sure the hissing is a vacume leak?
When I had a leak on a previous turbo I found that there was crack in one of the lines and that it was not at a connection point.
good luck

 

hi
the first side is on the vacuum side of the turbo and may not effect the pressure build but will effect the MAF reading(its getting air that its not metering) which will cause the car to act up


the second side the pressure side is the critical side... i would look at the upper and lower intercooler connections the metal lip of the ic pipe must sit flush ainst the body of the ic... the hoses must snap in with 2 clicks... look for the wire retaining clip and be sure its fully seated in the intercooler housing ... if a hose is blown off be sure to check and make sure the o ring is properly seated in the o ring grove on the ci hose

if all is well on the ic side of things work your way upto the throttle body and check the coupler there

let me know what you find out
tim

 

Thanks Tim

I've got the back of the car stripped at the moment
I've checked the IC connectors and they're all ok

The car drives fine, no shuddering or juddering or anything. Just smooth slowish acceleration until 0.4bar

Can't figure out where this damn leak is coming from and I don't want to do any mods until everythings running right

I'm thinking I might have to go the route of diy smoke testing

 

Am I right in thinking it is possible to have a small leak in the vacuum side without having any issues?

Tim, I think what you're saying is that my leak (or at least one of them) has to be on the compressor side after the turbos becase I'm losing boost, and you can't lose boost on the vacuum

As my car runs smoothly I would say I gave no issues with unmetered air
So if I do have a leak on the vacuum side it's only noticed when running the compressor through it

My connections from the turbos through the intercoolers and upto the Ypipe are all good

I'm starting to think it could be after the Ypipe that's the issue for me

Do you have any pointers on what to check next?

 

Only hitting .4 bar means your car is in limp mode, if the ecu sees something going on it will put it in limp mode regardless of where the leak is.

The most common areas for leaks is the connections at the intercoolers or the hoses around the DV's (f-hose, 1/4" hoses, etc. or the DV's themselves). I had one of the 1/4" hoses going to the top of the rear DV split on mine.

 

Do you have upgraded WG's and DV's, I don't think I caught reading that part. Is you car flashed? I also sent you a PM regarding something else.

 

Hmmm.... Well ther are a ton of clamps/hoses after the tb I did find a huge leak on mine the conector between the plenun and the intake runner was loose.. Ill be interested in what u find
Tim

 

Art - car is stock except DVs nothing else has been done
DVs are fine, no leaks there

Tim - how on earth do you tighten those clamps with the engine in the car??

 

When doing the leak test, can air pass through the throttle body?

Can air get through here and make a hissing sound too?

 

Another easy way to check DV's is to blow in them. If air goes through it means they are bad. Seems like Tim is helping you a great deal on this one, hope you guys find the issue. Best of luck!!

 

Ok ther trick to tightening those clamps... I used a real long screwdriver to rotate the clamp and used a 1/4 inch drive socket with a swivel and a couple extensions then I held the clamp in place with the screwdriver to prevent it from rotating

As far as air passing through the tb yes it can typicaly you will hear a hiss when a hose is leaking however when everything is sealed up u will hear a lower internal air leak that is the air passing by the valves so that being said just an fyi the system will never hold 100% u will still get valve blowby

 

I was gonna post earlier, but yes, air can get through the throttle body, ableit, only a little, but enough to hear. Maybe that is all your hearing and you are "limping" because of something else? The first time I boost leak tested mine, I thought I had a leak, turned out no. Have you scanned it with Durametric yet? Might tell you what the problem is, even if it isn't throwing a light.

 

lower the motor on the nuts till they come off.. about 2 inches....
take out ur Y pipe.. pressure test the TB.. you will see whats up...