Odd over-boost situation? Any BTDT's?

[Swann, Benjamin R. (BSWANN)]

Taka,

I've had the MM hose go a couple of times with the additional boost.  The
typical failure is such that it blows air out readily under boost, but then
seals(somewhat) under vaceum.  Any extra unmetered air that may enter while
under vaceum is compensated, to a point, by the OXY sensor - that is the car
seems to run just fine.  Of course a little duct-tape will get you farther,
and a fair number of wraps ensures you will be able to drive even in the
boost range until you get a delivery from thepartsconnection or wherever.  I
would imagine a massive blowout would cause a large enough air leak to stall
the car.

Actually I've witnessed the failure occur on at least 4 different cars,
stock and boosted, all in the same spot.  Right at the bottom in the middle
rib.  I suppose they can fail in other ways, but that's how I've seen them
go.   I would guess the guys who work on these for a living see this day in
and day out.

As you recall, I got tired (and broke) of blowing mine, and didn't wan't to
shell out for the hight priced SAMCO hose, so the stainless clamp wrap from
Home depot ~$5 installed over a new hose has worked just fine and I haven't
had a failure yet.  This works, because they tend to fail in the middle, so
you can leave about 3/4" of the flex portion exposed on the ends.  Actually
I had a good fis with some goo and black tape - that thing wasn't going to
blow, but it looked ugly.

Sooner or later I'll get around to installing the bypass valve which is
sitting on my bench.

I concur with the overboost description you gave below.

Ben

[Ben,
I don't know if Jim has worked on the vacuum system at all,
so no progress on that front.

Igor mentioned that if you have a tear in your Michelin Man hose
on the 10v, you'd most likely stall a lot and not be able to really
drive the car at all.

Lower wastegate hose is the biggest culprit of overboosting. Feels
really nice when you have lots of boost off the line, until the
fuel cut-off snaps your neck forward. :-O

Taka]

[Taylor,

Yep - much BTDT about this.

It is not your Michelin Man hose - that would cause the boost to stop at
about 1 Bar and not go any higher.

It is likely the lower wastegae hose or something in that part of that loop.
Possibly the wastegate diaphragm, but don't go ther until you've been over
all of the hoses.

Once you fix it, you'll miss the extra boost you were getting, so you might
wnat to chip it.

Ben
http://www.homestead.com/ben_swann/boostin.html]

[Greetings all,

After replacing the throttle body switch and multi-function sensor due to
low boost, I got full boost back (1.4) on my.. I will see 1.5 bar fast and
the car will cut out
for a brief second leading me to believe I probably have a vacuum leak in
the Michelin man hose or wastegate hose... snip..]