boost leak tester

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V8Sam

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had a fueling issue that throws up lights and all sorts on a freinds S3 for a while now

changed two new mafs with no joy, so think its time to get it boost leak tested

gonna try a home made baked bean can type.

any tips on testing it? also what valve should i use? just a regular Tyre valve one with some silicon sealant around it?

from what i gather one the tool has been made, pop it into turbo intake, run the pressure up to boost psi and listen out for leaks?

i have one of the old tyre inflater type things, you know press down for air press half way to let air out, so hopefully i should be able to gauge the psi in there and it wont blow anything to bits?

unless ofcouse anyone has a smoke tester near berkshire that id be able to borrow, paid of course.
 
same as before
17535 Fuel Trim; bank 1 (mult): system too rich)
 
taken FPR off and checked for debris? this is a code normally associated to a blockage in the fuel rail that increases fuel pressure and the ECU tries to pull fuel out to compensate... the code is thrown when it hits 25%

Check fuel trims in block 32

<tuffty/>
 
done before mate (was you who suggested it before) clean as a whistle

can only do trims etc from idle as annoyingly my laptop wont hold charge, so going for a drive with and doing logs isnt possible

seem to run lump sometimes and find the next though, hence why the mafs been changed, twice, no joy.

boost leak test was my next option.

http://www.ebay.co.uk/itm/Tyre-Whee...587548&hash=item3391383ab1:g:AW0AAOSwGzlTr9gZ

wondering it that valve would work for a DIY kit?
 
Last edited:
big *** boost leak is plausible all the fuel and non of the air... would imagine it would be fairly obvious to manage -25% fuel trims

<tuffty/>
 
o2 sensors dont show any faults, EGT has flagged up immitent from time to time. its on some checks not on others.

unless its a vac leak? but thought that was for running lean?
 
Vac leaks tend to add fuel as under vacuum it will suck in unmetered air... under boost it will turn into a pressure leak as the pressure will force metered air out causing the ECU to pull out fuel...

The too rich code is thrown because the ECU hit its limit of what it can pull out... the ECU is thinking it needs to pull fuel for whatever reason...

Possible reasons for this could be...

A blockage in the fuel return line somehow which would cause excessive fuel pressure making the injectors flow more for a given on time...

Too large an injector fitted for some reason and not mapped in...

A very large boost leak...

Faulty MAF...

Faulty injector (suspect that may throw a code but never seen an issue with one as yet)

Faulty lambda probe...

<tuffty/>
 
ive had system too lean once or twice on the codes, but always the system too rich. sometimes its clears its self out of the 5psi mode and runs fine then it pops back up again with engine light on. and back to 5psi

best way to test for a vac leak?

no idea how to check for fuel line blockages?!

maf has been changed, lambda behaves as it should

injectors are standard i believe

boost leak is what im hunting next, it does like to judder a lot coming of boost and sometimes like its trying to stall, even if its low pressure.

problems problems eh!

what you think of that valve? that be ok for a leak tester?
 
To test the charge system for leaks using the method you propose you will need to pull the hose off the throttle body and the charge pipe.. this would only really allow you to test from the end of the charge pipe to the manifold... you can't realistically test with the hose on the TB as you will simply blow through into open inlet valves and you would never get enough air if to be useful..

For a proper (mostly definitive) test you would need to get a smoke test...

99% of leaks are from the pipes attached to the inlet mani... 'L' pipe under mani (centre) that goes to the plastic air pump jobber and other paraphernalia, the pipe off the air pump jobber to the PCV valve and the 'V' pipe that comes off the outlet at the opposite end of the mani to the TB

<tuffty/>
 
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