Boost Leak test

[GSR94T]

Hi

my car shows boost but it aint movin! no obvious hoses loose or splits in any vaccuum lines that i can see

process of elimination time...

firstly, im going to do a boost leak test by hooking up a tester (http://www.vfaq.com/mods/ICtester.html) to the intake side of the turbo
now there are a couple of points i wish to clarify as I have read a few sites with mixed opinions?!

ok, I know that I have to disconnect my manual boost controller as this is something multiple websites agree on (as they bleed air and will defeat purpose of testing) so to do this, ill just run the boost source hose straight to the actuator - easy done.
now because im running the boost tester directly onto the turbos air intake side, i will be taking my intake pipe/air filter/flow meter off the car completely of course.

the questions:

Q1) this leaves my blowoff valve with nowhere to plumbback (evo 8MR blowoff) - i assume this wont be a problem as it will just be like an atmospheric unit?

Q2) my blowoff valve return vaccuum is T-pieced into the boost source line which goes to the actuator. Firstly im unsure if this is correct as my mechanic done it. Though can i leave it t-pieced into this line ?? (and of course as mentioned earlier ensure I have temporarily taken out my manual boost controller for the duration of this test)

Q3) my pcv valve on the rocker cover goes into the intake. Now that my intake will be disconnected altogether, am i best just blocking off this hose? or will it not be a factor under these testing conditions?

and finally

Q4) besides the turbo air intake side, should I hook up this boost leak tester to any other areas such as the intercooler piping or throttle body (examples only) and if so where exactly?

thanks guys i appreciate any help

 

[CLuTZ]

Unless your car is running noticeably like shit or you are running no AFM, then perhaps a leak is not what your problem is. Usually when you have a leak, your car will start cutting out and will be unusually laggy.

If you are making loads of boost and its not going anywhere then you might have a problem with the turbo itself?

 

[GSR94T]

Usually when you have a leak, your car will start cutting out and will be unusually laggy.

both symptoms are happening. noticeably laggy and it cut out once when hammering it on freeway

i dont want to go into it a whole lot more than this because i dont want this post to steer to other directions because im going to do this leak test regardless then straight off to a reputable mechanic/tuner

If you are making loads of boost and its not going anywhere then you might have a problem with the turbo itself?

hopefully its not the turbo its a 6 months old brand new 16G from gtpumps http://www.gtpumps.com.au/turbo.html which apparently arent the cheap copy ones



ok guys so does anyone have answers to my first post about whether to blockoff the pcv hose etc.

thanks

 

[Liberoz]

I use welsh plugs to block of any associated hoses when doing a boost leak test.

Someoen else had a similar issue and so did i just reciently and my issue was I had taken terminals off battery and had just pushed them on with tightening them up snug, maybe check this as it definately doesnt sound like a boost leak issue to me!

 

[lozza]

Q1) this leaves my blowoff valve with nowhere to plumbback (evo 8MR blowoff) - i assume this wont be a problem as it will just be like an atmospheric unit?

Q2) my blowoff valve return vaccuum is T-pieced into the boost source line which goes to the actuator. Firstly im unsure if this is correct as my mechanic done it. Though can i leave it t-pieced into this line ?? (and of course as mentioned earlier ensure I have temporarily taken out my manual boost controller for the duration of this test)

Q3) my pcv valve on the rocker cover goes into the intake. Now that my intake will be disconnected altogether, am i best just blocking off this hose? or will it not be a factor under these testing conditions?

and finally

Q4) besides the turbo air intake side, should I hook up this boost leak tester to any other areas such as the intercooler piping or throttle body (examples only) and if so where exactly?

1. won't matter
2. they're all vacuum sourced (w/g, bov) so multiple T-pieces from the same vacuum source (within reason ) is OK
3. the PCV closes under boost so this won't matter unless it is faulty
4. why do you want to hook it up anywhere else. you're as upstream as you can get ???
5. unless you are deaf it is NOT a vacuum leak (of the magnitude you are referring to would hiss like hell and be easy to detect without a boost leak test),

WHICH HAS BEEN SAID 3 X NOW!!!

good luck

 

[GSR94T]

thanks for those answers as they will be very helpful.

whether its my problem or not ill find out. i had a mate who had a leak which we couldnt hear. he had it smoke tested though (as we didnt know of this method), fixed the leak and the car ran a LOAD better

i feel i have nothing to lose by running this test, i dont need to buy anything for the test besides a valve, and if it doesnt resolve anything then its off to a good mechanic... so theres no need to get smart with comments about being deaf and expressing your distress by WRITING IN CAPS!!!!!!!!

this is a technical forum which is here to assist peoples enquiries and provide opinions on issues, and the reason a lot of people don't post questions is because theyre worried about attitude and smart comments

I myself am not worried .. because i know if you , or anyone else were here in person expressing their opinion on the problem, that they'd be expressing it in a lot nicer tone.

 

[CLuTZ]

No need to be defensive dude- everyone is here to help.....

I hear what you are saying about just doing a leak test anyway. Alot of people should be doing this aswell- because for one reason or another, their cars arnen't be running to their potential, and even a small leak can cause issues.

What I suggest is that you do is before you run the leak test, make sure your car is actually converting boost pressure into power and torque.

Were there any things you did to the car before you started getting these symptoms?

 

[GSR94T]

No need to be defensive dude- everyone if here to help.....

I hear what you are saying about just doing a leak test anyway. Alot of people should be doing this aswell- because for one reason or another, their cars arnen't be running to their potential, and even a small leak can cause issues.

What I suggest is that you do is before you run the leak test, make sure your car is actually converting boost pressure into power and torque.

Were there any things you did to the car before you started getting these symptoms?

im happy to hear anyones opinion on the issue at hand and believe me i am more than greatful for the help i receive on here - thanks guys... but im not going to stand for anyone trying to demean me just to make themselves feel better.

if i have misinterpreted what was written - i apologise, but it didnt look that way.

anyway away from all the crap

What was done to the car prior to the issue occuring -

clutch was slipping for a few weeks. got some cash together and had it replaced at meek.

ran the clutch in without giving it too much hammer, now that its run in, started driving it hard and the car shows boost but its not moving like it did when i had the 16g first put on.
Liberoz went for a drive with me in it and he can tell you that his car on 15psi would put mine to absolute shame even though im on 18psi.

we changed the plugs and i forgot what chris gapped them to, i have magnecore leads. took it for a quick run with datalogger, and based on the data the timing was adjusted. This made things a tad better, but nowhere near how it should/has performed. i think there were still a few knock counts too

we ran out of time and i need to take the car back, but it was suggested a possible boost leak. This is why i want to check it out before taking it back

anyone have any other ideas

thanks

 

[rob323]

I would encourage everyone to learn how to pressure test their intake systems. It may not fix the main problem but it costs almost nothing to do and helps you learn how the intake system works. And it can be surprising just how much of a difference to power and economy fixing all the little leaks makes.

 

[GSR94T]

I found a leak. main boost source vaccuum hose had two cracks in it (but hidden so was hard to find on visual inspection)
Replaced this with silicon vacuum, and every vaccuum hose in the engine bay is now silicon
Boosting loads better now as youd imagine

Anyway ANOTHER issue has arose

Currently the car is boosting at 18psi.

Problem: when i flat stick it (not every time, maybe 1 in 4 times) if i keep the foot down , when it reaches maybe 6-7000RPM it will just give one big jerk/clunk as if something has cut out. Its not jerking or stumbling as it hits high revs while driving as if it were starving for fuel or something, its as if it has one big cut out (but the car does not stall or turn off)

Ok quick car specs if it helps:
I have new blitz panel air filter in stock airbox with 055 AFM, 750cc injectors, walbro fuel pump (rewired with a relay for constant voltage), gsr ecu which was chipped and later reflashed by meek when i put the 16G turbo on (not sure of the extent that it was tuned, maybe it was a quick tune). all forged internals rebuilt maybe 20K ago with 16G turbo (about 5000kms since brand new from GTPUMPS)

Now my question. what causes this:

Although its not a progressive jerk, does a cut out indicate that there is an air/fuel issue?

Do I need a full re-tune altogether?

Is this a knock count issue - and if so what causes it?

Is the ECU set to have a boost cut out perhaps?

Is it an entirely different issue altogether?

 

[Dean]

sounds very very similar to what happened to me,
only when you up the boost again it would cut out.
it turned out to be my fuel pump,
it also sounds like its been played with in the past.
so my bet is that thats your issue

 

[BMGTZ]

have you checked your tacho against another.....it may be reving higher than your tachi shows and hitting the limiter

 

[GSR94T]

nah definately not that

ive hit limiter in the past. and it just throws the revs back...

this on the other hand just full CLUNK - cut out

 

[rob323]

Sounds a lot like boost cut. Maybe call Meek to see if they didn't remove it on the chip.