*Opinions Wanted* - Potential Boost Leak?

[Dredknut]

I am going to describe my situation in as much detail as possible, so forgive the lengthy post.

SITUATION:
Recently I have been getting the feeling that the car has a minor boost leak. Approximately 5000km ago, I chipped the car with APR Stage 1. I typically run the 91 octane file, and occasionally run the 93 octane file. According to my boost gauge, when I initially got the chip while running the 91 octane file, I would briefly peak around 20 psi and level off around 16-17 psi towards redline. Recently, I have noticed that I seem to be peaking 19 psi and holding approximately 15-16 psi to redline. I can't hear any hissing under the hood outside of normal engine noise.

Now we all know how innaccurate and inconsistent mechanical boost gauges can be, and I am aware of this fact. However, if you consider these numbers relative to one another, I feel like I have developed a boost leak somewhere thats causing me to lose 1-1.5 psi.

I will *hopefully* have access to a vagcom cable in a couple weeks, so I can definetively determine if my actual psi levels are meeting specified. In the mean time however, I am hoping that some of you can shed some light on possible locations of a potential boost leak, as well as offer some insight into my boost gauge situation.

MODS:
2007 GTI with DSG, 82000km on the odo, relevant mods as follows:
- APR Stage 1
- AWE Vent Mounted Boost Gauge
- Neuspeed P-Flo
- BSH DV Relocation
- BSH Boost Tap
- BSH Stage 1 PCV Fix

THINGS TO CONSIDER:
Firstly, I purchased my boost gauge second hand off of a forum member on here. The needle has never really sat right on "0" and as time has gone by, the needle has migrated farther from the "0" when the car is turned off. Here is a pic to illustrate what I mean:

My first question is: Would the fact that my needle doesn't sit directly on "0" affect the PSI and inHg readings the gauge gives? ie. if the gauge is about 2mm off of "0", will all of my readings be the same 2mm off? My assumption to date has been YES, however I figured I would throw it out there. I have had this gauge installed for a while, long before I was chipped. The needle has always been "off".

When driving, if I let off the gas completely and let the car coast, my gauge doesn't sit right at -20 inHg, more like -17inHg or -18inHg. This was the same before and after I got chipped. Here is what my gauge looks like when coasting:

When I am stopped and idling at a light, my gauge will read slightly higher at -15 to -17inHg. This was the same before and after I got chipped. The reading varies, however this pic shows about the lowest inHg value my gauge will read when the car is idling at operating temp:

Considering my gauge is off to begin with, do these inHg values seem normal? My opinion so far has been that my coasting inHg is normal because of the needle being off "0" to begin with. However, my idle inHg has NEVER been as low as coasting... Is this normal? Does anyone else with a properly working boost gauge and no discernable boost leak have the same readings?

WHAT I'VE CHECKED SO FAR:
This is what I have checked so far in hopes of identifying a boost leak and fixing my gauge readings:

- OEM IC hoses. I got under the car and checked the connections here. My understanding is that there is some play in the OEM "snap fit" connections with that wire ring thingy... My hoses on both sides of the IC both were able to move about 1-2mm with the wire snap ring in place. This play is normal and wouldn't cause any boost pressure to escape, at least thats what I have read. Is this true, or is this "play" in the connections potentially causing boost pressure to leak?

- Boost Tap and Vacuum Line connections. I am confident that all of the connections associated with my Boost Tap, Boost Gauge and Forge DV are not leaking. I have replaced these connections numerous times for various reasons, and my gauge readings have remained the same.

- BSH PCV Block Off Plate. I have removed the plate and repositioned it, and checked the gasket for leaks. I have re-tightened the OEM screws that fasten it to the plastic valve cover, as much as I dare in fear of stripping the plastic. I did notice however that there is a small gap between the valve cover and the BSH plate on the upper passenger side. This is not due to the design of the BSH part, it has to do with the fastener locations. Here is what I mean:

The gap is approximately 1mm at its widest point. This plate is torqued down as much as I dare, however if you look down that space you can see the OEM orange PCV gasket. If you look at the plate closer to one of the fasteners, the plate makes contact with the valve cover, there is no space and the PCV gasket is not visible. Would this gap potentially cause a boost leak? My guess is no as the 100's of people out there with any aftermarket PCV solution would all have boost leaks... However, given that I can easily see the gasket, wouldn't it be easy for boost pressure to escape here? Does anyone else have this gap?

THINGS I HAVEN'T CHECKED:
Rear PCV. Visual inspection looks fine, however is there any chance that if my rear PCV has failed, that I might experience a boost leak? Is the rear PCV even functional beyond being a pressurized tube if you have an aftermarket PCV block off plate installed? The rear PCV is the tube with the ring clamp on it in the middle of this pic:

IN SUMMARY:
These are the questions I am looking to have answered:

- Would the fact that my needle doesn't sit directly on "0" affect the PSI and inHg readings the gauge gives? ie. if the gauge is about 2mm off of "0", will all of my readings be the same 2mm off? Are my inHg readings normal given what I have described above?

- Are my APR Stage 1 boost levels normal? Should I be peaking 19 psi and holding 16ish to redline? More? Less?

- Would any 1-2mm of "play" in the OEM IC "snap fit" wire connections potentially causing boost pressure to leak? If so, is there a way to DIY fix this or should I consult my dealer?

- Would a 1mm gap between between the BSH plate and the valve cover when the bolts are fully torqued down cause a boost leak? Does anyone else have a gap?

- Is there any chance that if my rear PCV has failed, that I might experience a boost leak? Is it worth removing my intake and MAF heatshield to check?

Thanks for taking the time to read and any insight anyone can offer would be awesome... I know its hard to diagnose if something is wrong without logs, but I will hopefully have some done asap and get them posted. I don't know if this is all in my head or if I infact to have a minor boost leak somewhere...? Or perhaps my gauge readings are making me worry without cause... :mad0259:

 

[DBCPerformance]

Dan,

If you are 1-1.5psi short in times, that might be normal (actual boost vs. requested boost). The tube in the rear is a common problem I see more on more nowaday.

 

[Dredknut]

Dan,

If you are 1-1.5psi short in times, that might be normal (actual boost vs. requested boost). The tube in the rear is a common problem I see more on more nowaday.

So what your saying is that rear PCV tube might be causing some issues? Would it cause a boost leak, or my gauge readings to be off?

I really don't want to take my MAF heatshield off lol, but if its worth it to check I will.

PM'd you btw :smile:

 

[ssunnylee24]

mine is not on 0 either, it's actually on 1~2 HG.

 

[Phil@BSH]

Couple things:

1. The PCV plate in our setup never see's boost so you would/could never lose it there.

2. The same is true for the rear pcv hose.

3. You will need to log your setup to be sure as different ambient conditions will make it easier/more difficult for the vehicle to reach a requested load value which is what the ECM actually wants to see. In many cases boost is an erroneous number although it is one that is often deemed most important. Load is a measure of output and truly is what matters.

4. Should you in fact have a leak the easiest and most sure fire way to locate it is through a pressure test.

 

[Dredknut]

Couple things:

1. The PCV plate in our setup never see's boost so you would/could never lose it there.

2. The same is true for the rear pcv hose.

3. You will need to log your setup to be sure as different ambient conditions will make it easier/more difficult for the vehicle to reach a requested load value which is what the ECM actually wants to see. In many cases boost is an erroneous number although it is one that is often deemed most important. Load is a measure of output and truly is what matters.

4. Should you in fact have a leak the easiest and most sure fire way to locate it is through a pressure test.

Thanks for confirming the plate and rear PCV hose Phil. I wasn't aware that that part of the engine didn't experience boost pressurization, which is obvious from my original post :lol: Thanks for your insight.

Besides actual/specified PSI, do you have any suggestions as to other data I should be looking at and log? Which sets of data determine load?

Again all, forgive my lack of knowledge on some of this stuff... This is a learning experience for me. :thumbsup:

 

[07Noside]

Thanks for confirming the plate and rear PCV hose Phil. I wasn't aware that that part of the engine didn't experience boost pressurization, which is obvious from my original post :lol: Thanks for your insight.

Besides actual/specified PSI, do you have any suggestions as to other data I should be looking at and log? Which sets of data determine load?

Again all, forgive my lack of knowledge on some of this stuff... This is a learning experience for me. :thumbsup:

IF your looking for a boost leak just log boost actual/specified and the N75 Duty cycle. If your charge air path is relatively stock. Look at everything post turbo. The system is relatively simple, seeing that you already have the pcv fix done that out of the question. Check the C-clipped couplers on the IC hoses. I've seen on my car over time about 50k miles that the O rings on them just tore for no reason and caused a slight leak. Check your DV and all vac lines for a boost gauge or anything. If it doesn't look completely sealed chances are its not.

As far as your question for the play in the oem ic couplers thats normal, they have o rings inside of them that seal when pressure is applied or when vac is applied. As long as those O rings are not hanging out with the play its normal.
Here's an over view of the charge air system

 

[Dredknut]

IF your looking for a boost leak just log boost actual/specified and the N75 Duty cycle. If your charge air path is relatively stock. Look at everything post turbo. The system is relatively simple, seeing that you already have the pcv fix done that out of the question. Check the C-clipped couplers on the IC hoses. I've seen on my car over time about 50k miles that the O rings on them just tore for no reason and caused a slight leak. Check your DV and all vac lines for a boost gauge or anything. If it doesn't look completely sealed chances are its not.

As far as your question for the play in the oem ic couplers thats normal, they have o rings inside of them that seal when pressure is applied or when vac is applied. As long as those O rings are not hanging out with the play its normal.

Thanks Noside, that pic is great!

When I install my winter wheels, I am going to get under the car again and have a better look at those IC hoses. I didn't really inspect the o-rings when I was down there, all I did was remove that wire clamp on each side and disconnect the hoses for a visual inspection. Other than a little oil in the pipe (which I assume is because I don't have a catch can yet), everything seemed fine.

I have noticed though that there is a metal lip on the OEM hoses that is serves as a "stop" when you push the hose into the connection on the IC itself. On my passenger side connection, when you look down from the top of the engine bay I can see that metal lip sitting 1-2mm from the IC connection. When I reinstalled that hose, I pushed that metal fitting all the way in, it wasn't visible from the engine bay.

This is the best pic I could manage, the red line's indicate the 1-2mm I am talking about:

This concerns me because the hose has been pushed out of the IC fitting and I am wondering if that is causing a leak. Like, the wire ring clamp is still in place and the hose won't pop out, but I am thinking that 1-2mm that the connection has been "pushed out" might allow boost pressure to leak?

 

[Dredknut]

mine is not on 0 either, it's actually on 1~2 HG.

Do you think this affects your readings? Are they off because you're gauge is off? Do you sit right at -20inHg when at idle/coasting?