Phantom Boost

[Paul Meyers]

OK, all you ECU heads out there, wrap your minds around this:

Over the weekend I finally found the reason for my anemic boost. The hose
from the firewall to the ECU had a huge, gaping, impossibly large hole in it
just before the filter near the passenger footwell! This was caused by heat
from the infamous "connector" where the alternator wire meets the battery
wire under the floormat on the front passenger side. Apparently, the Audi
engineers thought it would be ok to bundle a whole bunch of stuff together
to keep it out of the way. It had apparently gotten so hot (from internal
resistance due to the fabled "green slime") that the rubber had crumbled
away inside the hose. Even the braiding was long gone. What was left was a
hole the size of a quarter open to the atmosphere!.

Now here's the question, with a hole this impossibly large, how could the
ECU have ever sensed any boost? While I was pressing my heavy foot to the
firewall, the boost meter was reading an occasional 1.4 bar at 5000 or so
RPM. Doesn't the ECU put out the signal that is displayed by the boost
meter? If so, how could it, with no pressure input?! If the boost meter gets
its input from some other source, what does the boost output signal at pin
17 do? Doesn't it go to the boost pressure gauge? What gives?

Paul Meyers
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