[Sniz]

(Questions at bottom)

Working on diagnosing where I am loosing boost on my car today. I will put together a "DIY" if I complete this successfully, but first I need some technical help from some of you. I do not want to do this incorrectly and break something on my engine. I'm assuming that I need to pick the right hosing to attach my air compressor to (will be regulated to 15-20psi).


A little background on the problem at hand. I have been unable to produce any datalogs where the car is holding anything above 10psi (not on valet mode) w/ any consistency. Several datalogs were done in the very cold temps, but not all.

Here is a datalog of a 1st-4th run where you can see the boost problems, especially in 3rd. In 1st the boost went higher than I have ever seen, then 2nd produced psi in the 12's, however in 3rd the boost starts around 8psi then gets to 10psi and then drops back down to below 8psi all in 3rd gear. The puzzling thing is that 4th gear then holds a consistent 10psi (which is still low) without any of the fluctuations seen in 3rd gear.

I personally think its the diverter valves not doing their job of handling the higher boost, but I want to rule out any boost leaks first.





My 2 choices are as follows:

1) The 2 outpipes from the airbox (filter). These are plastic flexible hosing that I believe were not designed to contain pressurized air. I was thinking of making a Y-pipe from pvc and flexible hosing that I would attach the compressor to w/ a male fitting.

See here:

Rear intake out pipe


Front intake out pipe (also pictured is the intercooler out pipe I can easily access to pressurize the system, this is the outpipe from the intercooler to the engine)


Close up of the outpipe from intercooler



Here are my concerns, I am trying to be cautious here.

1) Pressurizing from the intake outpipes will introduce highly pressurized air into a part of the system not designed to handle boost, air will be forced into the diverters from the opposite side of their intention. I initially thought of doing it this way until I thought about it more, bad idea?? I dont want to damage anything!!! the good part about pressurizing from here is that no part of the air handling system will be bypassed other than the stock airbox, so any potential leaking areas will be involved.

2) Pressurizing from the coldside of the intercooler back will increase airflow and pressure coming from the opposite direction of the turbos. Will this cause a problem w/ the turine's being forced in the wrong direction or will the air compressor not even spin the turbo's and just pressurize the air inside them?

As you can see I've never done this before but I'm pretty determined to find the leak in my system (if it even exists). Also, do you guys this that pressurizing the system will induce a leak out of the diverters if that is the weak link that is causing my reduction in boost levels??

[O-cha]

I would start from the cold side of the intercooler and pressurize the IC toward the TB then worry about the IC to the turbo area.

http://www.realoem.com/bmw/partgrp.d...14&hg=13&fg=20

Looking at this though, just try to pressurize it from the 2 intakes, thats just flexible hosing to deal with the engine twist, the rest looks solid.

[Sniz]

gotcha, I was considering that too

[O-cha]

Also I know there's another thread on this and I'm sure you did, but to make sure, you did check the DV right?

[Sniz]

Originally Posted by O-cha

Also I know there's another thread on this and I'm sure you did, but to make sure, you did check the DV right?

they seem to be locked in tight, other than jiggling the things what else should I do with them? The front DV is very snug, the rear is a bit loose but seems to be locked in.

[O-cha]

Originally Posted by Sniz

they seem to be locked in tight, other than jiggling the things what else should I do with them? The front DV is very snug, the rear is a bit loose but seems to be locked in.

No no, to check for a tear in the diaphragm. You would have to pull them off, even just blowing into them you should know if there was a tear. Then pressure test them to see if they are opening early (not likely).

[Sniz]

Originally Posted by O-cha

No no, to check for a tear in the diaphragm. You would have to pull them off, even just blowing into them you should know if there was a tear. Then pressure test them to see if they are opening early (not likely).

Gotcha, no to figure out how to get them off. I did notice the rear DV had a lot of dirt/oil around it that could result from air escaping.

[O-cha]

They are really easy to get off, same type as clip as the hoses at the base of the DV. The dirts normal, I would be more worried if it was clean since air would push away dirt, but anyway thats not what I'm talking about. a tear in the diaphragm of the DV as in air is flowing through it while its not actually open.

[Sniz]

Originally Posted by O-cha

They are really easy to get off, same type as clip as the hoses at the base of the DV. The dirts normal, I would be more worried if it was clean since air would push away dirt, but anyway thats not what I'm talking about. a tear in the diaphragm of the DV as in air is flowing through it while its not actually open.

got them off, I cant hear any air leaking when I blow into them. I'm sure I can't blow 10psi though and it seems that they are holding some boost at least, not totally ruined if the DV is the cause.

[O-cha]

Originally Posted by Sniz

Do they just spin to unlock?

The DV or to get them off the pipe? To get them off the pipe they have the same gray lock connector as the hose, which spins to unlock. The DV itself is sealed and does not open

[RetroGamerJP]

Sniz... I am experienceing a similar problem with my boost pressure. Cant seem to come close to 15psi and am averaging around 10 with 12.5 peak... I suspect a leak as well. I would definately say to charge the input side of the IC... please share your setup with us as I would love to perfore the same test on my setup. Likewise I'll share any findings.

many thanks

[O-cha]

Oh and did you try it with the stock map?

[Sniz]

Originally Posted by O-cha

Oh and did you try it with the stock map?

yup used the bypass plugs and ran stock for a day, no problems.

[Sniz]

DV off, rear one I tested by blowing thru w/ it still connected to car.

[O-cha]

Originally Posted by Sniz

yup used the bypass plugs and ran stock for a day, no problems.

So it's only low while @ 14psi or with the procede on. try the stock MAP though see what it does. While mine was being ghey it worked fine with the stock map but freaked with the tuned one though so it's not to say its not the procede. I'd put money on the DV if it was a leak though.

[O-cha]

Originally Posted by Sniz

DV off, rear one I tested by blowing thru w/ it still connected to car.

Since you have the compressor though I would pressure test them before bothering with the charge piping since it's easier and they are the weak link. Just throw pressure at them until they crack open. They should hold 4 psi.

[Sniz]

Originally Posted by O-cha

So it's only low while @ 14psi or with the procede on. try the stock MAP though see what it does. While mine was being ghey it worked fine with the stock map but freaked with the tuned one though so it's not to say its not the procede. I'd put money on the DV if it was a leak though.

Its only running low w/ the Procede on I believe, although I do not have a boost gauge at this time (I need one!). If I can I'll get the car to a shop up the road and run it on their dyno in stock form to see if its having any issues. So far it has not popped any codes in stock form however.

I'm putting my $$ on the DV too, so I'm actually going to call the activities quits for today. Forge units should be in around New Years so I may just keep the 335 parked and drive my truck until then.



If the forge units don't do the trick then it will be back to the drawing board.

Hey, at least I figured out how to remove the airbox and the DV. Will come in handy soon enough w/ the new DV's coming in and new intake in the future.


Thanks for the help!! I'll report back when the Forge DV's are in.

Happy Holidays!

[Sniz]

Originally Posted by O-cha

Since you have the compressor though I would pressure test them before bothering with the charge piping since it's easier and they are the weak link. Just throw pressure at them until they crack open. They should hold 4 psi.

Only 4psi??? I will test the DV's today.

[O-cha]

Originally Posted by Sniz

Only 4psi??? I will test the DV's today.

Yes sine the vacuum side, which under boost is exposed to the same boost pressure as the other side, is exposed to atmosphere.