Another reason Audi doesn't go

[Ned Ritchie <NED@IntendedAcceleration.com>]

Add this to your turbo troubleshooting fixes:

A few months ago I supplied one of the principals at ALL DATA, the folks
who supply the automotive service manuals on CD, a package for his S6
for over 350 hp.  This package simply included the following:

   Special turbo
   Special computer
   Special exhaust manifold

According to the technicians at ALL DATA, the car would go like "gang
busters" and then the boost would smoothly back itself off to about 12
PSIG. (No stronger wastegate spring pressure was used to force the boost
higher than the computer controlled amount)

After months of checking & testing about everything guess what was the
problem?

ALL DATA's technicians hooked several 4-channel lab scopes to about
every input & output on the engine. The lab scopes showed a slight
ripple in the output from the Mass Air Flow Meter and reduction of pulse
width on the fuel injectors.

In previous experiments with other S4 enhancement systems they had
installed a K&N cone air filter.  They didn't think the ripple was
enough to worry about but one tech said "hook back up the stock air
box."  Going back to the stock air box that had the plastic air
straightening passages corrected the problem!

Apparently the cone filter when supplying enough air for over 25 PSIG of
boost created just enough turbulence to upset the reading from the hot
wire and cause the engine computer to reduce fuel and reduce maximum
allowed boost.

This also makes me think about the "?power tubes?" that are placed in
the air intake track, and that I now see being advertized in "Turbo &
High Tech Performance" magazine.  I guess I'll have to test one.

Ned Ritchie