[s-cars] What constitutes a leak?

[djdawson2@aol.com]

 Tony,
Not really.  The only intake concerns that you should have, that could ultimately affect mixture, lie between the MAF and the intake valves.  The amount of air that could leak between a non "o" ringed Garrett turbo compressor housing and its backing plate, would never be substantial enough to do this.
 
Think about this mathematically...  Let's say the engine is running at a moderate speed, under moderate boost... let's say a 200cfm consumption rate.  Let's also say that you expect a stio mixture of 14.7 to 1, but you're seeing 13.7 to 1.  What does this mean, in terms of a leak of metered air?  Well, from a simple mathematical perspective, this would mean a leak of about 14cfm.  That's a bunch of air... certainly audible.  Chasing the source of air ultimately getting to your tailpipe is, IMHO, a wasted effort.  There do exist paths for this to occur, and this is not related to your problem.  If an air leak were your problem, the leak would be found between MAF and intake port, and would be very audible during a pressure test.
 
For these reasons, I think you're barking up the wrong tree, WRT to your mixture problem.
Hope this helps...
Dave
 
-----Original Message-----
From: Tony Guttmann <T.Guttmann at ms.unimelb.edu.au>
To: djdawson2 at aol.com
Cc: s-car-list at audifans.com
Sent: Thu, 18 Aug 2005 06:20:12 +1000
Subject: Re: [s-cars] What constitutes a leak?


Dear Dave,

s noted in my original message, I also plugged the big hose that enters
the throttle body housing (i.e. the intake manifold an the opposite side
of the block to the exhaust manifold). Thus, as far as I'm aware I'm not
allowing the air to go down each intake runner.

Does this change your response?

Thanks,

Tony