[Biturbos4] Re: [2..7t] hunting for boost leaks?
audiguy at gmail.com
Sun Nov 14 14:17:48 EST 2004
OK, I've done some homework and leak testing.... here are the details.
On Wed, 10 Nov 2004 09:16:26 -0700, Jim Green <jim.green at gmail.com> wrote:
> On Tue, 9 Nov 2004 22:19:32 -0500, David Kavanagh <audiguy at gmail.com> wrote:
> > I was measuring block 115 which shows expected boost and actual boost
> > as the car is running. From what I can tell, the actual values are a
> > bit off from the expected values when the engine is under load. So, I
> > went on a hunt for a boost leak (I should also mention, I've been
> > monitoring a MAF with low output for many months now).
> > I tested the bypass valves. They both hold a vacuum and the diaphram
> > moves predictably as I apply a vacuum. I checked that hose that
> > connects the 2 pipes to the throttle body. I felt around after
> > unhooking those 2 pipes and can't feel any rips or tears. The hoses
> > that connect to the bypass valves seem intact also. Are there any
> > others I should have been worrying about? Anything else that might
> > cause low boost?
> > Bear in mind, I don't know if the boost is all that much lower than it
> > should be. I might also be seeing lower boost because the MAF output
> > is lower than the computer can adjust for (via fuel trim). It still
> > isn't throwing certain codes that will cause Audi to replace it under
> > warranty (which is my goal instead of shelling out $250 for a new one
> > myself).
> > Anyway, any other trouble areas with respect to boost leaks on these engines?
> The best way to really test for boost leaks is to pressurize the whole
> system. This might be a royal PITA on your car, but pull the turbo
> outlet hoses off, plug them with whatever you can find at Home Depot.
> Find a port or T into a boost line that will fill the entire intake
> with compressed air. 15-20 psi will usually tell all.
> Jim Green
> '89 90tq
> '89 80q
'00 A6 biturbo 6-speed
'01 allroad 6-speed
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