Boost Leak Testing

Mario8P

Mario8P

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Hello guys!

First of all Merry Christmas to all.

Today I bumped into a weird issue. Was boost leak testing using compressed air pumped into the turbo inlet (where the intake pipe goes into) while oil cap off, when i start pressurising the system, all the air pumped in all the air gets out of the oil filler. can't even have the gauge on the boost leak tester to move beyond zero, nor my boost gauge.

Car is suffering from a boost leak somewhere as it's not pulling add hard as before and feels so slow. Even VCDS logs illustrate boost leak as am not reaching the requested boost

Need all your help and input please
 
Would it be worth smoke testing to see we're its escaping from ?
 
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If your losing your air through the oil cap then that means that your front pcv valve is faulty.
In that case you'll be losing boost pressure, also putting boost oressure in to your engines breather system.
 
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Marshy said:
If your losing your air through the oil cap then that means that your front pcv valve is faulty.
In that case you'll be losing boost pressure, also putting boost oressure in to your engines breather system.
Click to expand...
Sorry Marshy for not mentioning that I have a forge catch can fitted.
 
The more I think about it, if your putting air in the turbo inlet you may get air in to the rocker cover through the rear pcv which is normal.
Do I remember you fitted a BCS powervalve with the boost tap take off?
When I got my powervalve system I found my car had lost the edge a bit.
I found the o-ring on the boost tap was nipped and leaking boost.
Some Vaseline on the o-ring and bingo it's been perfect since.
 
Marshy said:
The more I think about it, if your putting air in the turbo inlet you may get air in to the rocker cover through the rear pcv which is normal.
Do I remember you fitted a BCS powervalve with the boost tap take off?
When I got my powervalve system I found my car had lost the edge a bit.
I found the o-ring on the boost tap was nipped and leaking boost.
Some Vaseline on the o-ring and bingo it's been perfect since.
Click to expand...
Wasn't me running stock axleback at the moment.
Not sure I'd replacing the rear crankcase tube that has the built in check valve.
I have no other ideas as the car is running like crap.
 
Update.
Plugged off the rear crankcase breather tube and pressurised the system. And I don't have any boost leaks!

Not sure what to do next.
 
Update 2:
Replaced MAF
Replaced Spark plugs
Replaced DV

Replacing MAP sensor now to try. Wish me luck.

Next would be N75 sensor or actuator itself!

***

I thought if I have a faulty N75 Rick@unicorn can inform me from the logs I sent but seems like the readings are fine
 
Looking at that your making more boost than my stage 2+ but your air mass is lower than mine?
Looking at that it doesn't look like you have a boost leak, although you have a bit of timing pull.
Who's map are you running?
 
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timing pull is due to insanely bad fuel. Thats what lead me to run Water Methanol.
The tune am running is by Rick@Unicorn. Was still dialing in the water methanol kit as this tune isn't finalised by any means.

man this is very annoying! the car feels slower than stock exhaust note not sharp as before, and the DSG fart is almost gone.
I really dont know how to explain it.

Marshy how does my N75 readings seem? My only luck is to replace the N75 sensor as i replaced every possible sensor other than the O2 and the N75
 
I haven't logged my N75 and I'm no expert but I think yours look ok.
Your Lambda readings are very similar to mine too.
Not sure where you go with this mate.
 
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If my actuator is failing it wont show on the logs right?
Aaaargh this is so frustrating
 
I'm really not sure.
I was trying to find some of my logs showing fuel pressure to compare but I seem to have deleted them!
Have you logged fuel pressure actual vs specified?
Also the fuel low pressure?
Your cars making boost so I would look elsewhere, you've tried MAF and MAP sensors you've no pcv and you've changed DV.
Just my opinion though.
 
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Didn't check any other logs to be honest.
Will replace my fuel filter tomorrow or the day after.
Things I did today was:
Plugged rear breather hose and pressurized the system to check for boost leaks (none found)
Reinstalled my stock DV instead of the DV+
Replaced MAP sensor
Replaced MAF sensor
Replaced Spark Plugs

Thank god my friend owns a VAG parts shop which I have full access to!
 
Your making plenty boost so I'd rule a boost leak out.
If you log your fuel pressures it'll either highlight a problem or you can rule that out too.
Your very lucky having access to parts though.
 
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audi upgrades
Will have to check them tomorrow morning.
But i think a DTC will pop up as soon as the fuel rail pressure is either high or low.
 
That log doesn't look as good.
Your boost seems to drop off higher up the revs and is over 200mbar less than specified in places.
My log shows my fuel pressure stays above 100 bar consistently above 2000 rpm
 
Here's a log from a couple of months ago for you to compare.
ImageUploadedByTapatalk1419715295203974
 
Marshy said:
That log doesn't look as good.
Your boost seems to drop off higher up the revs and is over 200mbar less than specified in places.
My log shows my fuel pressure stays above 100 bar consistently above 2000 rpm
Click to expand...
I wish Rick will have the time to shed some light on my issue
I know he might be very busy tho
 
audi upgrades
By the way today I noticed that while cruising my intake sound (air sucking) is kinda loud and occurring on low rpms. Before having my issues, I could only hear it while the turbo was spooling.

I don't get it. It feels like there is a boost leak somewhere. But how come nothing showed up when I pressurised the system. Unless some parts doesn't get pressurised when manually


Plus sometimes when I let off the gas a little bang comes out of the exhaust
 
Okay. Tomorrow going to be a big day for me.
Going to take off my valve cover to inspect if my camshaft chain have skipped a tooth. I might be very lucky if this is what causing my issues due to not having any motor damage (hopefully).

From doing some online reading/research there are some people who had this issue without having any engine damage, while others have suffered from catastrophic engine damage.


Wish me luck guys I'll need it!
 
Good luck mate.
You'd think it would be running like a bag of crap though?
Do you need any too,s to check it? Or is it marked up?
 
Marshy said:
Good luck mate.
You'd think it would be running like a bag of **** though?
Do you need any too,s to check it? Or is it marked up?
Click to expand...
Thanks Marshy!
I read online, and some people had the same symptoms as mine.
I can't think of anything else, as I replaced almost everything.

Regarding tools I have no clue but for sure there are markings to check timing.
 
I'd be interested to hear your findings
Any pics of timing marks or just the general condition of chain and tensioner would be helpful.
 
Just a thought but you say you can hear a sucking/breathing noise from the intake ! is your elbow pipe correctly fitted to top of turbo with no damage etc ?

I only say this as when i fitted my Revo intake it was a complete PITA with that spring clip that holds it on to the the turbo inlet... When doing mine i thought that it would be easy to damage that part and not know and also not have it sit correctly and either have a gap or come off after a few miles creating a gap.

Now this elbow is after you MAF or MAP sensor cant remember which one, but there could be unaccounted air entering the turbo....

Just a thought..

Rich
 
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Marshy said:
I'd be interested to hear your findings
Any pics of timing marks or just the general condition of chain and tensioner would be helpful.
Click to expand...
Will keep you posted bro. I'll take photos when I take off the cover. Postponed my schedule till Sunday
 
S3DUST said:
Just a thought but you say you can hear a sucking/breathing noise from the intake ! is your elbow pipe correctly fitted to top of turbo with no damage etc ?

I only say this as when i fitted my Revo intake it was a complete PITA with that spring clip that holds it on to the the turbo inlet... When doing mine i thought that it would be easy to damage that part and not know and also not have it sit correctly and either have a gap or come off after a few miles creating a gap.

Now this elbow is after you MAF or MAP sensor cant remember which one, but there could be unaccounted air entering the turbo....

Just a thought..

Rich
Click to expand...

Appreciate your suggestion Rich! Thank you.

Wouldn't it show when I boost leak tested? When I pumped compressed air to the compressor inlet l pressurised about 25psi and couldn't hear anything and pressure wasn't dropping ~1 psi per second was dropping (which is expected because oil cap is off)
 
Hi Mario,
Mario8P said:
Appreciate your suggestion Rich! Thank you.

Wouldn't it show when I boost leak tested? When I pumped compressed air to the compressor inlet l pressurised about 25psi and couldn't hear anything and pressure wasn't dropping ~1 psi per second was dropping (which is expected because oil cap is off)
Click to expand...

Yes sorry i missed that part of your post.... if you compressed it from that elbow then yes it would leak if you had a problem there :( What intake do you have on it ? does it have the correct scaling for the MAF
 
audi upgrades
S3DUST said:
Hi Mario,


Yes sorry i missed that part of your post.... if you compressed it from that elbow then yes it would leak if you had a problem there :( What intake do you have on it ? does it have the correct scaling for the MAF
Click to expand...
Running Unitronic CAI MAF reading is on kinda low ~230 but it's been like that since day 1 (compared old logs to new ones)
 
Good luck mate, i hate it when things arn't right and your just waiting for that Eureka moment...
 
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Little update guys!

Took off my valve cover and found out that my intake camshaft have missed a tooth and its timing has changed. Thank god there are no major damage to the engine.


63191d49b307507f73a1c7a241d9b346.jpg


954b6e626f8022b04c17d7e490fa9c86.jpg


Just from looking at the pictures you can see that they are not aligned

Tomorrow going to get all needed parts to replace my chain tensioner, chain, all other hardware
 
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I've just bought a set of tools as looking to change my chain and tensioner this year.
Looking at the pics it look like the inlet cam has advanced a tooth.
Be interesting what you find when you try to fit the locking tool.
I'm not sure at what angle the cams sit for the tool to fit.
 
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